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Quanta-Ray MOPO-HF - Spectra

1. 7 OPERATE A OPERATE1 500 000 SETUP1 SETUP MONITOR1 1220 814nm LOCAL MONITOR 1 F4 Fo F3 Fa Fs NG Returns control to front panel Figure 6 8 Returning Local Control to the System 1 Press F to place the cursor under the digit to be changed Use the up down buttons to scroll the number to the digit desired Repeat this procedure to select the second digit When the new address is selected activate the IEEE 488 at this address by holding in F until it beeps de wr Baud Rate Selection The default serial baud rate is 2400 but it can be changed to 300 or 1200 To change it 1 Press F to indicate the serial address is to be changed 2 Usethe up down buttons to scroll to the baud rate desired 3 Activate the serial interface at the selected baud rate by holding in F until it beeps The Display Nothing is displayed in the large window The Function Keys F LOCAL IEEE 488 RS 232 LOCAL sets system control to either the front panel local or to the IEEE 488 or the RS 232 interface The selec tion is shown in the display box F IEEE 488 0 31 sets the address for the IEEE 488 parallel interface as shown in the display box See IEEE 488 Address Selection above for information on changing this address F4 BAUD 300 1200 2400 sets th
2. MONITOR Y F4 Fo F3 Fa Fs N No of scans Scan starting Scan ending Scan speed or No of shots for each to be performed wavelength wavelength increment wavelength Select 0 shots for continuous scan Figure 6 5 The Setup1 Menu Press the SETUP button at any time to display this menu This menu allows you to set the number of scans to be performed as well as the starting and ending wavelengths When SHOTS is set to 0 CONT is displayed over F to indicate a continuous scan is selected 1 e there will 6 15 Quanta Ray MOPO HF Optical Parametric Oscillator 6 16 be no dwell during the scan Just below CONT is the scan rate in nm s When SHOTS is set to 1 or greater INCR is displayed over F to indicate the system is set for an incremental scan An incremental scan starts at the beginning wavelength then moves by the nm increments xxx nm shown under INCR The scan stops dwells at each increment and the system delivers the number of shots displayed under SHOTS The scan then progresses and repeats this process until it reaches the scan END wave length The MOPO HF scan rate is nonlinear because the it is dependent on the rotation of the BBO crystals and the beam angles and beam angle vs wave length is a nonlinear function The maximum scan rate is lower for scans in the blue end o
3. G Spectra Physics 2 n lt En SINE DRIVE MOTO Digital Controller Front View Digital Controller Rear View Figure 2 3 CE CDRH Radiation Control Drawing 2 5 Quanta Ray MOPO HF Optical Parametric Oscillator CE CDRH Warning Labels VISIBLE AND INVISIBLE LASER RADIATION IS EMITTED FROM THIS APERTURE SEE MANUAL AVOID EXPOSURE CDRH Aperture Label 1 CE Aperture Labels Large and Small 2 ATION AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION POWER WAVELENGTH S AND PULSE WIDTH DEPEND ON PUMP OPTIONS AND LASER CON FIGURATION VISIBLE amp INVISIBLE LASER RADI SEE MANUAL CLASS IV LASER PRODUCT 0448 8690 CDRH Danger Label 5 CDRH Danger Label Non Interlocked 3 VISIBLE AND INVISIBLE LASER RADIATION WHEN OPEN AVOID SKIN OR EYE EXPOSURE TO DIRECT OR SCATTERED RADIATION SEE MANUAL 0452 0150 CE Danger Label Non Interlocked 4 VISIBLE AND OR INVISIBLE LASER RADIATION AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION CLASS 4 LASER PRODUCT POWER WAVELENGTH S AND PULSE WIDTH DEPEND ON PUMP OPTIONS AND LASER CONFIGURATION SEE MANUAL 0451 8080 P O BOX 7013 SPECTRA PHYSICS LASERS MT VIEW CALIFOR
4. STB anything other than zero REM WHILE Wavelength lt gt GotoWL old style Wait for GOTO to finish WHILE STB lt gt 0 wait for GOTO to finish Cmd read wlen GOSUB WriteMopo GOSUB ReadMopo Wavelength VAL Response Cmd stb read SCPI status byte GOSUB WriteMopo GOSUB ReadMopo STB VAL Response PRINT TotalLoops multiloop multiloopmax Wavelength Wavelength PRINT STB STB IF DoWaits THEN GOSUB WaitFiveSeconds WEND ContinScanSetup REM GOTO IncrScanSetup PRIN PRINT Setting up continuous scan PRINT TotalLoops TotalLoops MultiLoop multiloop PRIN ScanBegin 365 multiloop Start at 365 000 nm ScanEnd 367 multiloop Stop at 367 000 nm Quanta Ray MOPO HF Optical Parametric Oscillator Rate 1 100 picometers second Shots 0 Continuous scan scans 2 Make two passes Cmd source begin STR ScanBegin GOSUB WriteMopo Cmd source end STR ScanEnd GOSUB WriteMopo Cmd source rate STR S Rate GOSUB WriteMopo Cmd source shots STR Shots GOSUB WriteMopo Cmd source scans STR scans GOSUB WriteMopo CONTINUOUS SCAN SETUP VERIFICATION GOSUB ReadSetup faultflag 0 IF Responsel lt gt ScanBegin THEN faultflag 1
5. leeren 3 8 Figure 3 10 MOPO HF Turning Curves oocoococcc I aaa 3 9 Figure 3 11 Outline Drawings lsseeeseeele mue 3 12 Figure 4 1 The MOPO HF Beam Path oooccoccccoc eee eens 4 1 Figure 4 2 MOPO HF Connectors Right Side View a eens 4 9 Figure 4 3 The Digital Controller Front Panel lt 0 00000 cece tenes 4 9 Figure 4 4 The Digital Controller Back Panel 0000 e cece eee eee 4 10 Figure 5 1 A Typical Right angle Turning Prism Assembly 00 000 eee eee ee 5 2 Figure 5 2 Typical Table Layout for a PRO Series Pump Laser and the MOPO HF 5 3 Figure 5 3 The MOPO HF Beam Path and Optical Layout cece eee eee 5 5 Figure 5 4 Reference beam alignment for the master oscillator MO BBHR is removed to allow the reference beam into the optical cavity For purposes of clarity some optical components have not been shown cette 5 8 Figure 5 5 Unpolarized light from a HeNe laser shown entering a birefringent crystal such as BDO vets eset eee laced A eee Pad Cees 5 8 Figure 5 6 Horizontally polarized light passing through a birefringent crystal such as BBO 5 9 Figure 5 7 Tuning Mirror Adjustments liliis 5 11 Figure 5 8 Placement of pick off prism assembly for master oscillator pump energy measurement sre a m siren iiion a e A NGE e don ear Galle cate ond orte a Sey Rina 5 14 Figure 5 9 Placement of MO BBHR for pum
6. WaitFiveSeconds IMER Timel ABS Timel TIMER m Timel Time2 WH El Time2 WEND SOUND 1000 3 SOUND 2000 2 RETURN Time2 lt 5 NKAKKK AKK KAKAK AK KAKAK KAKAK KAKAK KK KK KK AKK AKK KAKAK ck Sk Ck ko ck Ck ko ck ck ko ko Sk Ck ko ko ko ko KK SUB GpibError Msg PR PR INT GPIB NG INT Msg END SUB SUB MopoError Msg PR PR INT MOPO INT Msg END SUB B 26 STATIC STATIC AN Wi n Wl Connections The RS 232 IEEE 488 Interface Table B 1 IBM PC AT Serial Port Pinout Computer or Terminal MOPO HF FDO RS 232 C Signal Pin No Pin No PinNo Signal Signal Name 25 Pin 9 Pin Transmit Data TXD 2 3 3 RXD Receive Data RXD 3 2 2 TXD Request To Send RTS 4 7 5 CTS Clear To Send CTS 5 8 4 RTS Data Set Ready DSR 6 6 6 DTR Data Carrier Detect DCD 8 1 8 DCD Data terminal Ready DTR 20 4 20 DSR Signal Ground 7 5 7 Protective Ground 1 SHELL SHELL PC Computer MOPO National Instruments GPIB PC IIIA Card IRQ7 DRQ1 DACK1 O o ojojo Wi OO 00 0 O O ojojo ojo 00 0 National Instruments GPIB PC IIIA Card Dipswitc h o ojojo o o OojJOo 00 0 ojojo o o ojo 00 0 IRQ7 DRQ3 DACK3 Figure B 1 IEEE 488 Dip Switch and Jumper Settings 1 0 Ta Dipswitch EBEN This side of the dip swit
7. cette 1 2 The Advantage of the MOPO HF e e aaa mms 1 3 Patents cue a A O ex de E uet seg eut idend e bee es 1 3 Chapter 2 Laser Safety is 66 kaa aa a aaa eee ieee xxu Rp RR eee 2 1 Precautions For The Safe Operation Of Class IV High Power Lasers 00000ee eee 2 1 Focused Back Reflection Safety a aa ea ea aaa eaaa aa tees 2 3 Maintenance Necessary to Keep this Laser Product in Compliance with Center for Devices and Radiological Health CDRH Regulations 0 00 c cet 2 3 Safety Interlocks 2o eee eee ed ere Pe dn m ere ie a aan jane Fane bates 2 4 Battery Disposal ea sy a ae ake Bo ek a daa E a eat ace CRIS a KN ocios die 2 4 CE CDRH Radiation Control Drawing a ete eee 2 5 CE CDRH Warning Labels a ea eee 2 6 Label Translations sn we aa wa aga AKA eet eee 2 7 CE Declaration of Conformity 0 asasan eee 2 9 CE Declaration of Conformity 00 000 mm 2 10 Sources for Additional Information a nen 2 11 Laser Safety Standards ccc rrr 2 11 Equipment and Training sak gaga TAN A Ke aga e aa ga Ka GAR a ad E m rr 2 12 vii Quanta Ray MOPO HF Optical Parametric Oscillator Chapter 3 Description seperate De dee Y e o ar x n Ai 3 1 OPO Theory of Operation caridad ee pede bude diene A a dv eum ia 3 1 BBO Enables OPO Commercialization_ a rh 3 2 MOPO Operation 321 ka sa NG a NR bebes ete e Cele nang Ga A delet a e
8. 5 PRINT Begin ScanBegin Responsel PRINT End ScanEnd Response2 PRINT Rate Rate Response3 PRINT Shots Shots Response4 PRINT Scans scans Responsed PRINT IF faultflag 1 THEN PRINT Continuous Scan Setup ERROR PRINT Program Terminated END END IF PRINT 1 scan PRINT Continuous scan running PRINT types Cont GOSUB WaitForScan IncrScanSetup PRINT Setting up incremental scan of idler range PRINT ScanBegin 365 multiloop ScanEnd 375 multiloop n Increment 2 2 nanometer steps Shots 100 100 shots at each WL scans 3 Make thr passes PRINT 1 source begin ScanBegin PRINT 1 source end ScanEnd PRINT 1 source incr Increment PRINT 1 source shots Shots PRINT 1 source scans scans The RS 232 IEEE 488 Interface INCREMENTAL SCAN SETUP VERIFICAT ON GOSUB ReadSetup faultflag 0 IF Responsel lt gt ScanBegin THEN faul tf ag IF Response2 lt gt ScanEnd THEN faultflag IF Response6 lt gt Increment THEN faultflag IF Response4 lt gt Shots THEN faultflag IF Response5 lt gt scans THEN faultflag PRINT PRINT Incremental Scan Setu
9. GOSUB readdata wl VAL response PRINT type TotalLoops multiloop multiloopmax count WEND RETURN WaitFiveSeconds Timel TIMER Time2 Timel WHILE ABS Timel Time2 lt 5 Time2 TIMER WEND SOUND 1000 3 SOUND 2000 2 RETURN The following is a sample program that tests the optional GPIB IEEE 488 interface NK KKK KE AKK KAKAK KKK KKK KEK KKK KKK KKK KKK KKK KKK ck ck Sk Ck ko ck Ck ko ck ck ko ko KKK ko ko ko KK DOUBGPIB BAS DOUBLER GPIB INTERFACE TEST 02 09 95 NK KKK KKK KKK KK KKK KKK KE KKK KKK KKK KKK KEK KKK KKK ck ck Ck ck ck Ck ko ck ck ko ko KKK ko ko ko Ax x COMMON SHARED NISTATBLK IBSTAS BERRS BCNTS IBCNTL amp AN AN wl wl The RS 232 IEEE 488 Interface CONST EERR CONST TIMO amp H8000 Error detected amp H4000 Timeout DECLARE SU DECLARE SU DECLARE SU DECLARE SU BCLR BYVAL BD BFIND BDNAMES BD BRD BYVAL BD RDS BWRT BYVAL BD WRTS UJ UJ UJ UJ DECLARE SUB GpibError Msg DECLARE SUB MopoError Msg CLS PRINT GPIB initialization PRINT BDNAMES Dev Mopo CALL IBFIND BD
10. IF Response2 lt gt ScanEnd THEN faultflag 1 IF Response3 lt gt Rate THEN faultflag 1 IF Response4 lt gt Shots THEN faultflag IF Response5 lt gt scans THEN faultflag PRINT aa Y Continuous Scan Setup multiloop multiloop of multiloopmax PRINT TotalLoops TotalLoops PRINT d PRINT Parameter Sent Received PRINT A PRINT Begin ScanBegin Responsel PRINT End ScanEnd Response2 PRINT Rate Rate Response3 PRINT Shots Shots Response4 PRINT Scans scans Responsed PRINT IF faultflag 1 THEN PRINT Continuous Scan Setup ERROR B 20 The RS 232 IEEE 488 Interface PRINT Program Terminated Cmd scan GOSUB WriteMopo 4 PRINT Continuous scan running PRINT types Cont GOSUB WaitForScan IncrScanSetup INCREMENTAL SCAN SETUP n PRINT Setting up incremental scan PRINT ScanBegin 220 multiloop ScanEnd 240 multiloop Increment 2 2 nanometer steps Shots 100 100 shots at each WL scans 3 Make three passes Cmd source begin STRS ScanBegin GOSUB WriteMopo Cmd source end STR ScanEnd GOSUB WriteMopo Cmd source incr STRS Increment GOSUB WriteMopo Cmd source shots
11. Activate TABLE by holding the M OSC key in until it beeps Repeat this procedure to set P OSC to TABLE Caution W If tables have been previously written for the system skip this next step and proceed to the next section Perform the following procedure only if a prior table has not been written or if the current table is no longer valid e g 1f there has been a loss of table data data corruption grating re calibration movement or realignment of crystal potentiometers a b amp g h Load the default look up tables for the MO and PO Enter the Setup2 menu Press the DEVICE key it will highlight Use the up down keys to set the device to MO CRYS To activate it press the DEVICE key until it beeps Press the METHOD key it will highlight Use the up down keys to set the method to Y SHIFT To activate it press the METHOD key until it beeps Access the ABORT button in the Setup 2 menu then press it for several seconds until it beeps A Delete message will appear Press the ABORT key again until 1t beeps The MO default look up tables will load and become active In the same manner select DEVICE PO CRYS and repeat this pro cedure to load the default tables for the PO This completes the installation phase Continue to the next section to align the system Alignment Establish the Reference Beam for the Master Oscillator 1 Place an aperture assembly on the dowel pins at PH
12. If the mirror adjustments are running out of range loosen the MO TM base plate screws and rotate the mirror in the desired direction of adjust ment Re tighten the screws Alternatively loosen MO TM and rotate it the desired amount The adjustment adds a negligible perturbation to the cavity alignment therefore it should not alter the calibration 13 14 15 16 17 Remove the pick off prism from its location between MO TM and MO TM Place PH onto its dowel pins Place the flat side of the aperture so it is facing the positive lens If you removed MO TMg replace it Adjust MO TM so the pump beam is retro reflected onto the center of the PH pinhole aperture Figure 5 13 Remove Pho This completes the master oscillator overlap procedure 5 19 Quanta Ray MOPO HF Optical Parametric Oscillator PH Pinhole Horizontal Axis Pump beam retro reflection from MO TMg overlapped on the pinhole Figure 5 13 Retroreflection from MO TMg Attaining Oscillation in the Master Oscillator 1 Change to LONG PULSE mode 2 Place the pick off prism assembly in a position to intercept the output beam from the MO Figure 5 14 Direct the reference beam into a power meter The meter should be on the 0 1 W scale Be careful to prevent the Fresnel reflections from the surface of the prism from being reflected back into the MO This may cause a para sitic oscillation Power Oscillator To PO Pick
13. Caution n Be careful Hold the prism by the edges of its back plate Set the PRO Series controller to RUN NORMAL Once the MOPO HF is operating check the FDO UV output power If UV output is at full power the MOPO HF FDO is ready to operate If UV power is low try increasing it by slightly adjusting TP The ver tical axis is most sensitive This completes the conversion from MOPO HF to MOPO HF FDO output operation Switching from FDO to MOPO Operation l 2 4 Set the PRO Series controller to Q SWITCH OFF Move the FDO TP turning prism from its normal position to its parked position near the crystal and PB prism turntables Set system mode to SIGNAL or IDLER depending on the wavelength at which you will be working a From the Servicel menu press the MODE button then use the up down buttons to select SIGNAL or IDLER b Press the MODE button until it beeps to activate this selection Set the PRO Series controller to RUN NORMAL This completes the conversion from MOPO HF FDO to MOPO HF output operation 6 24 Running a Scan Operation Figure 6 10 shows a scan being initiated from the Operatel menu and the following procedure explains how to perform a scan Select OPERATE1 Indicates scan Indicates Track Current MOPO or FDO output menu progression or Table mode Current Signal or Idler output OPERATE A PERATE1 0 0 0 00 SCAN 1 M SETUP1 SETUP MONITOR1 DT L 1220 814nm GO
14. Introduction The Quanta Ray MOPO HF Optical Parametric Oscillator Overview Figure 1 1 The Quanta Ray MOPO HF System The principal of operation for an optical parametric oscillator OPO is quite different from that for a laser system Whereas a laser derives its gain from the spontaneous and stimulated emission generated by atomic transi tions an OPO s gain is derived from a nonlinear frequency conversion pro cess The atomic transitions in a laser have inherent linewidths which define the maximum tuning range of the laser For example a dye laser tunes over 20 nm per dye while Ti sapphire lasers can tune over 200 nm The most common tunable systems have historically been pulsed dye lasers which require 15 or more dye compounds to cover the visible wavelength range In contrast a 355 nm BBO based OPO can tune continuously from 440 nm to wavelengths greater than 2200 nm The MOPO HF high finesse OPO combines many of the popular features of the standard MOPO family with an even narrower linewidth oscillator Linewidths measured over a typical scanning range average less than 0 075 cm making MOPO HF linewidths comparable to those of pulsed dye laser systems This narrow linewidth capability extends the number of applications to which MOPO technology can be applied for example stud 1 1 Quanta Ray MOPO HF Optical Parametric Oscillator The MOPO OPO ies of combustion processes atmospheric chemistry and other gas
15. This warranty also does not apply to equipment or components that upon inspection by Spectra Physics discloses to be defective or unworkable due to abuse mishandling misuse alteration negligence improper installa tion unauthorized modification damage in transit or other causes beyond the control of Spectra Physics This warranty is in lieu of all other warranties expressed or implied and does not cover incidental or consequential loss The above warranty is valid for units purchased and used in the United States only Products with foreign destinations are subject to a warranty surcharge Return of the Instrument for Repair Contact your nearest Spectra Physics field sales office service center or local distributor for shipping instructions or an on site service appointment You are responsible for one way shipment of the defective part or instru ment to Spectra Physics We encourage you to use the original packing boxes to secure instruments during shipment If shipping boxes have been lost or destroyed we recom mend that you order new ones We can return instruments only in Spectra Physics containers Service Centers Customer Service Benelux Telephone 31 40 265 99 59 France Telephone 33 1 69 18 63 10 Germany and Export Countries Spectra Physics GmbH Guerickeweg 7 D 64291 Darmstadt Telephone 49 06151 708 0 Fax 49 06151 79102 Japan East Spectra Physics KK East Regional Office
16. 5 11 Quanta Ray MOPO HF Optical Parametric Oscillator 20 Place the PH aperture back into its mount Orient it so that the flat side is facing the BBO crystal 21 Place MO BBHR in its alignment position on the left hand side of the grating tuning mirror pair Figure 5 9 The mount should be oriented so that the front surface of the optic faces the BBO CRYSTAL This set up will be used to retro reflect the HeNe beam This alignment position for MO BBHR is used exclusively for assis tance in the subsequent overlap procedure It is distinct from its stan dard position in the MO cavity Note Make sure the mount is at least 10 mm from the edge of the grating to prevent mechanical interference during the adjustments 22 Adjust the MO BBHR horizontal so that the HeNe beam is retro reflected onto PH 23 Verify the beam is also overlapped with PH If not the retro reflected beam is missing the grating and is not folded back onto itself as desired If so a While viewing the beam on PH perform a clockwise adjustment on the MO BBHR so that the retro reflected beam is moving to the left b Continue this adjustment until the left going beam disappears and a right going beam becomes apparent c Overlap this beam with PH pinhole aperture and verify it is also overlapped with PH This completes the reference beam alignment for the master oscillator Master Oscillator Overlap Procedu
17. Orient the positive lens so its curved surface is directed away from the negative lens when it is placed in the beam line Do not yet mount the negative lens Place it safely aside in an optic box or wrapped in a piece of optical tissue Method B MOPO HF has been previously aligned 1 Mark the location of the PO PL mount on the translation stage with a pencil Remove the PO PL mount Leave PO NL in its designated position on the MOPO HF base plate Set the PO PL mount safely aside in an unoccupied hole in the MOPO HF base plate Remove the negative lens from the PO NL lens mount and place it safely aside in an optic box or wrapped in a piece of optical tissue Continuation of the Standard Procedure 1 The pump beam should be level and centered on PH Verify this and remove the aperture from the base plate Be sure to use an aperture with a fluorescent label or a business card taped to the flat side in order to view the beam If necessary center the beam on the pinhole by making make minor adjustments to UVBS If these adjustments are performed the beam must be re centered on PH and PH Leave the telescope lenses in place during these adjustments 5 31 Quanta Ray MOPO HF Optical Parametric Oscillator 5 32 Adjust the sheet polarizer so the reference beam is horizontally polar ized Verify the reference beam is still aligned PH PH and PH The pump beam should be roughly
18. Set the begin and end wavelength scan values to 460 and 660 nm From the Setupl menu use the method described under Setting Numeric Values on page 6 7 to enter the begin and end wavelength scan values F and Fa Select the MO crystal for optimization a From the Setup2 menu select the DEVICE button then use the up down buttons to scroll to MO_CRYS b Press and hold the DEVICE button until it beeps to activate your selection Select the linear interpolation method to write this table a Press the METHOD button then use the up down buttons to seroll to LIN INT b Press the METHOD button until it beeps to activate the selection and to move the system to the begin wavelength With the system at the begin wavelength watch the bar graph and use the up down buttons to optimize oscillation at that point Press CONT to move the system to the end wavelength Upon arriving at the end wavelength watch the bar graph and use the up down buttons to optimize oscillation Once optimized press CONT until 1t beeps Press SAVE until 1t beeps Repeat this procedure for the PO crystal starting at Step 2 This sets two of the main values required to generate a new table We will now write the base table for the entire tuning range from 440 to 690 nm 10 Perform the Lagrangian Table Writing Procedure below Operation Lagrangian Table Writing Procedure If oscillation of the master oscillator is not observed
19. readdata Response2 VAL response PRINT B 14 1 source rate GOSUB readdata Response3 VAL responses PRINT 1 source shots GOSUB readdata Response VAL response PRINT 1 source scans GOSUB readdata Response5 VAL responseS PRINT 1 source incr GOSUB readdata Response6 VAL responses RETURN The RS 232 IEEE 488 Interface Inputs None Outputs Responses readdata Chars NewChar WHILE NewChar lt gt CHRS 10 responses Chars WHILE EOF 1 WEND NewChar INPUTS 1 1 Chars Chars NewChar WEND RETURN Loop until LF is received Save all but the LF char Wait for next char Input next char Combine all chars WaitForScan count 0 WHILE count lt gt scans PRINT 1 read count GOSUB readdata IF DoWaits THEN GOSUB WaitFiveSeconds Wait for last scan to start Quanta Ray MOPO HF Optical Parametric Oscillator count VAL response PRINT 1 read wlen GOSUB readdata wl VAL response AN PRINT type TotalLoops multiloop multiloopmax count WEND WHILE count lt gt 0 Wait for last scan to finish IF DoWaits THEN GOSUB WaitFiveSeconds PRINT 1 read count GOSUB readdata count VAL response PRINT 1 read wlen
20. refer to Figure 5 3 Attach it to the base plate with a 10 32 screw Set up a HeNe alignment laser on the table as close to the MOPO HF as possible Figure 5 4 The HeNe laser output should be unpolarized If it is polarized orient the laser so the output is polarized at 45 This allows the output beam to be horizontally or vertically polarized as required in subsequent steps in the alignment procedure Appropriate polarization is achieved 5 7 Quanta Ray MOPO HF Optical Parametric Oscillator without misaligning the beam by placing a sheet polarizer in the beam path without misaligning the beam Step 3 m 1 Power Oscillator MO BBHR Reference Beam removed HeNe Laser Master Oscillator PH Gratin MO TM BBO AMO TM NZ A j Tuning Mirror Installation Aperture Figure 5 4 Reference beam alignment for the master oscillator MO BBHR is removed to allow the reference beam into the optical cavity For purposes of clarity some optical components have not been shown Unpolarized light from a HeNe laser that enters a birefringent crystal such as BBO will split into two separate beams referred to as ordinary o and extraordinary e rays see Figure 5 5 The two beams are orthogonally polarized i e the o ray is horizontally polarized while the e ray is verti cal In a negative uniaxial crystal such as BBO the e ray will walk off the initial beam path in a direction that is
21. 0 A setting of 1 or greater sets the system to incremental scan INCR see above The scan rate is set in nm sec and is limited to a maximum rate dictated by the wave length chosen F SHOTS XX sets the number of shots that will be issued during an incremental scan dwell If the number is set to 0 a continuous scan is selected Press this button to select it then press it repeatedly to select the digit you wish to change and use the up down buttons to set its numerical value Press the button again to move to the next digit etc Select the SETUP2 menu Current Signal wavelength Current Idler wavelength gt OPERATE 500 00 SETUP MONITOR V F4 F5 F3 Fa Fs Select the device Select the algorythm Set the base Set the peak Abort the current to be set to be applied to voltage for voltage for settings undo the device selected noise filtering noise filtering Figure 6 6 The Setup2 Menu The Setup2 menu appears when the SETUP button is pressed twice This menu allows you to manually manipulate the position of the MO or PO crystal separately by selecting MO or PO under F or to operate them simultaneously by selecting OPO You can also run one of seven table scan algorith
22. 1 Block the seed beam 2 Remove the hex wrench or other object used to misalign the output coupler The PO should be oscillating 3 If necessary make the adjustments to the OC to ensure the pump sig nal and idler are overlapped Check this with an IR card behind VDC This is a collinear phasematching geometry OPO Seeding 4 Unblock the seed beam Seeded operation should begin 5 Make minor adjustments to the PO crystal to ensure optimal frequency overlap Maximum power output should result This may be accom plished by using the Y_SHIFT operation for the PO device in the SCAN SETUP 2 menu Initialize PO Detector Throughout the alignment procedures the PO beam splitter BS2 must be out of the beam line because it introduces an uncompensated wedge see Figure 5 25 The final step in the procedure involves establishing PO detection 6 7 Change to LONG PULSE mode Place BS back onto the base plate Use the HeNe beam to roughly center the optic on the output beam path Leave the base plate screws loose BS should be oriented to reflect the output from the PO into POPD 5 43 Quanta Ray MOPO HF Optical Parametric Oscillator 5 44 10 11 Block the seed beam from the MO Change to Q SWITCH mode Unseeded oscillation should resume Check to see if the BS mount is clipping either the primary output beam or the Fresnel reflections directed onto POPD Burn paper may be used to evaluate the primary be
23. 380 1553 Laser Focus World Buyer s Guide Laser Focus World Penwell Publishing 10 Tara Blvd 5 Floor Nashua NH 03062 Tel 603 891 0123 Lasers and Optronics Buyer s Guide Lasers and Optronics Gordon Publications 301 Gibraltar Drive P O Box 650 Morris Plains NJ 07950 0650 Tel 973 292 5100 Photonics Spectra Buyer s Guide Photonics Spectra Laurin Publications Berkshire Common PO Box 4949 Pittsfield MA 01202 4949 Tel 413 499 0514 Chapter 3 Description OPO Theory of Operation The gain of an optical parametric oscillator OPO system is derived from the nonlinear interaction between an intense optical wave and a crystal hav ing a large nonlinear polarizability coefficient Beta Barium Borate BBO is a negative uniaxial crystal with intrinsic birefringence properties that are used to achieve critical phase matching required by this process OPO operation can be most easily understood as the inverse of the familiar nonlinear frequency mixing process used to generate harmonics in a Nd YAG laser For example the third harmonic of a Nd YAG laser is 355 nm and it is generated by mixing the 1064 nm fundamental output with the 532 nm second harmonic in a nonlinear crystal material such as BBO or KD P 9 P Fixed 1064nm 7 m BBO 355 nm 532nm 77 Figure 3 1 Frequency mixing to generate the third harmonic of Nd YAG An OPO works in the reverse fashion in which the energy contain
24. Customer Sevi iio Lo ad bee eA dee dead A de KG ada Ta KN a beaks 9 1 Warranty die ada dba iS 9 1 Quanta Ray MOPO HF Optical Parametric Oscillator Return of the Instrument for Repair eea tees 9 2 Service Centers ara api a hae bea yoke edie 4a a Ghee SES a DRESS 9 3 Appendix A Installing the BBO Crystal aaa aaa aaa aan A 1 Determining the Orientation of the Optical Axis in the Crystal 0 0000 cece eee A 1 A Quick Verification of the C axis Direction ssas saaana eae A 3 Installing the Crystal in the Mount a eR Hmmm re A 4 Master Oscillator 2 2 a na uaaa A 4 Power Oscillator csi Bee a a A ee Pes A 5 Appendix B The RS 232 IEEE 488 Interface lt a aaa aaa aan B 1 SCOPCSi aan ka a sae a etna D eps entes Meee Sas bole de geht dee B 1 OVerVIBW e exa odes di deed aa A A ye dor E bb an d att Gade pae B 1 Interface Commands cairn cox ES EA lee Se Tan Seat eel Oe alte glee seba B 2 Setup Operations and QuerieS 6 0c ren B 2 Read Only Commands uv ciar a hid a BAG Ah a ENG Ga shades be seh KR nara a bee B 2 Execution Commands misses aeni a E BN Aa BEG aa BGS id an B 2 IEEE 488 2 Mandatory Commands a ea a a aa aaa eaaa aaa aaa B 3 Installation esee A a Beate ee UR et d MR ee Geese ay tee tbe Sd s B 4 HS 232 C Interface iiie baa aueh eee dee i E Bk a AB a bbs cur e ag a B 4 IEEE 488 Interlace ns ieu be e Rer es KK aa PEE XS nS B 4 Selection RS232 IEEE LOCAL zeara ne
25. Plug Outlet and Socket Couplers for Indus trial Uses listed in the official Journal of the European Communities Environmental Specifications The environmental conditions under which the laser system will function are listed below Indoor use Altitude up to 2000 m Temperatures 10 C to 40 C Maximum relative humidity 80 non condensing for temperatures up to 31 C Mains supply voltage do not exceed 10 of the nominal voltage Insulation category II Pollution degree 2 Table of Contents Preface lt aaa aaa ag aaa aC C ee JR Ri a ad eae eRe R8 iii CE Environmental Specifications cee eee V CE Electrical Equipment Requirements liliis rn V Environmental Specifications l lliilseeee rn V Warning Convehtlons 3 2 13 c acea RR rd ee Oe RR a e Ro n xiii Standard Units Das ve tk Ewa eX XO EF Beads see rere ee Ea daas XV Unpacking and Inspection cs hh nre tees a dace xvii Unpacking Your MOPO HE i EX a eee eke REPE E RR RE ee Ree FER A xvii System Components xvii AECA in c A ja Piette pa ae Pa Ba Pan Mai a Bde apn Seve xvii Chapter 1 IntroduCUON is saa aa a aaa E da EGRE Ys 1 1 The Quanta Ray MOPO HF Optical Parametric Oscillator ooo ooooooooo o 1 1 OVOIVISW sor an e Ara aaa Bata cah Dearth a tate mate an OE na pet lanes Guy KANE eo ene teas cds 1 1 The MOPO OPO ciar i dee a ue bh eae dat hobo edd ote a 1 2 The MOPO Digital Controller
26. Response6 VAL Responses RETURN B 24 The RS 232 IEEE 488 Interface Inputs Cmd Outputs None WriteMopo CALL IBWRT Mopo Cmd F IBSTA AND EERR THEN CALL GpibError IBWRT ERROR RETURN Inputs None Outputs Responses ReadMopo Responses SPACES 40 CALL IBRD Mopo Responses F IBSTAS AND EERR THEN CALL GpibError IBRD ERROR RETURN WaitForScan Count 0 WHILE Count lt gt scans Wait for last scan to start IF DoWaits THEN GOSUB WaitFiveSeconds Cmd read count GOSUB WriteMopo GOSUB ReadMopo Count VAL Response Cmd read wlen GOSUB WriteMopo GOSUB ReadMopo Wl VAL Response PRINT type TotalLoops multiloop multiloopmax Count WEND AM AM H Wl B 25 Quanta Ray MOPO HF Optical Parametric Oscillator WHILE Count lt gt 0 IF DoWaits THEN GOSU Cmd read count GOSUB WriteMopo GOSUB ReadMopo Count Cmd read wlen GOSUB WriteMopo GOSUB ReadMopo Wl VAL Response PR WEND RETURN INT type TotalLoops multiloop B WaitFiveSeconds VAL Responses v s Wait for last scan to finish multiloopmax Count
27. The MOPO HF RS 232 interface is configured as data communications equipment DCE Table B 1 at the end of this appendix describes the inter face connectors and cabling The serial communications port of a typical computer is configured as data terminal equipment DTE A standard 9 wire RS 232 cable is required to connect a computer DTE device to the MOPO HF FDO DCE device Connection should be simple with no cross connections required MOPO FDO Serial Interface Parameters The parameter settings for the MOPO HF serial interface are eight data bits one stop bit no parity Configure the parameters of your computer s serial interface to match these BAUD Rate The MOPO HF serial interface baud rate can be set anywhere from 300 to 2400 bits per second Chapter 6 Operation describes how to set the baud rate For your convenience it is repeated below under Selection The IEEE 488 GPIB interface of the MOPO HF system is configured as a talker listener device 1 e it can both send and receive data Your com puter must also have talker listener and bus controller capabilities Use a standard GPIB cable to connect your computer GPIB interface to the MOPO HF The GPIB interface of the MOPO HF system includes a National Instru ments GPIB PC IIIA interface card that is installed inside the MOPO HF controller Table B 1 at the end of this appendix shows the dip switch and jumper settings for this card The card is shipped wit
28. and the movement between points the cali bration and the final save are all automatic when the MO_AUTO or OPO_AUTO method is selected F ABORT appears if a change has been made to the menu see the menu illustration under Selecting a Table Writing Method below A momen tary press aborts the current action and returns you to the previous menu Pressing the button until it beeps brings up the DELETE key see below F DELETE appears only after ABORT has been pressed until it beeps Caution Pressing the DELETE button until it beeps will delete the user defined values for the selected device and will replace them with default theoretical values A momentary press on the other hand unselects delete and returns you to the abort state The Remote Menu Operation Select the REMOTE menu gt OPERATE A OPERATE1 REMOTE SETUP MONITOR1 SELECT IEEE488 BAUD LOCAL 15 2400 MONITOR V Fs F5 F3 Fa Fs A Select the remote Set the IEEE488 Set the baud rate interface or address local Figure 6 7 The Remote Menu The Remote menu is accessed by pressing the SETUP button three times The Remote menu is used to select the system control source The default is the front panel or LOCAL but it can be se
29. decompose into two distinct light rays the extraordinary e and ordinary o rays This results in a double or split image of an object when it is viewed through the crystal This phenomenon is known as dou ble refraction The c axis is a unique direction in the crystal When light enters the crystal parallel to the c axis it does not split into two distinct rays therefore no double image will appear This fact may be used to quickly identify the c axis direction 1 Place the crystal over a thin line on a piece of paper Notice that the image of the line is split 2 Rotate the crystal in the direction that is perpendicular to the lines Notice that the line merge at a particular orientation 3 Use a pencil to draw a line from the corner of the crystal that is closest to the viewer to the opposite corner Figure A 4 This line is along the c axis a Face normal orientation b Counter clockwise rotation c Clockwise rotation AE 7 P c viewer viewer viewer BBO crystal Side View LA M7 Line a Split image of line Line moves apart Lines merge BBO Crystal Front View Figure A 4 Determining the C axis Figure A 4 shows the case where the c axis falls on the line that starts at the opposite lower corner and ends at the upper corner nearest the viewer In a the viewer observes the split image of a line through the crystal in a rn normal orientation As the crystal is rotated counterclockwise the lines are
30. it as outlined in the SSS procedure the number is already set Note you cannot set the BEGIN and END wavelength to a number outside the range allowed for the selected MODE the SIGNAL IDLER or FDO designated by the wavelength displayed in large digits If by error you try to do so the controller will beep and will not change the value of that digit Make sure the wavelength settings desired matches the mode you selected earlier via the OPERATE1 menu Please note as the sole exception to the setting numeric values proce dure the GOTO function of the Operate 1 menu requires that after selecting the numeric value as outlined in this procedure you set the value in order to initiate the goto function Powering Up the System Turn on the power switch on the rear of the unit The system will first per form an internal diagnostics routine which takes about 10 seconds then the front panel lights up and the Operatel menu is displayed At this point any of the menus listed below and shown in can be chosen The Menu Structure The following is a description of the controller s layout and functions The menus and commands that are necessary for operating the MOPO HF are also listed here The illustration below shows the three mode buttons the buttons to the left of the display and the services that are available through them The follow ing sections give a brief description of the various menus that are displayed wh
31. the Service menu is displayed Leaving the system on replace the new PCMCIA card with the origi nal card Press the FRMWRE UPDATE button then hold in the LOAD button until the system beeps Observe the various messages that indicate the status of the loading operation This loads your old data When the loading is complete replace the original PCMCIA card with the new one Hold in the SAVE button until the system beeps This saves the old data with the new software When the save process is completed leave the new PCMCIA card plugged in and replace the cover Turn the system off then back on to reboot the unit with the original data values and new firmware software All the settings that were in place using the original card including the IEEE address the baud rate and the local or remote mode setting should still be evident using the new card If you have just upgraded your system to include the FDO you will need to select the appropriate operating mode Notes Notes 1 Quanta Ray MOPO HF Optical Parametric Oscillator Notes 2 Notes Notes 3 Quanta Ray MOPO HF Optical Parametric Oscillator Notes 4 Notes Notes 5 Quanta Ray MOPO HF Optical Parametric Oscillator Notes 6 Report Form for Problems and Solutions We have provided this form to encourage you to tell us about any difficulties you have experienced in using your Spectra Physics instrument or its manual problems that did not require a formal
32. to center the apertured beam onto the PH pin hole c Adjust the PO RM to center the beam on PH Installation and Alignment d Iterate Steps b and c until the apertured beam is centered through the pinholes at PH and PH e Remove PH PH and PH Verify the beam is not clipping on PO RM 10 Overlap pump and HeNe beams a Remove PO TM b Place a pick off prism on the base plate where PO TM was located Orient the prism as depicted in Figure 5 24 c Locate the first surface reflection of the HeNe beam from PO TM Position the pick off prism to intercept this beam Direct the beam out the diagnostic port hole closest to PO TM on the front side of the MOPO HF Figure 5 24 d Place a beam dump on the side of the pump laser approximately 1 m in front of the port hole Position the beam dump so that the HeNe beam is directed into the input hole Pick off Prism PO TM removed MBD PO TM BBO A OT Power Oscillator Reference Beam Pump In Master Oscillator Long Pulse Figure 5 24 Power Oscillator Pick Off Prism Placement e Place a pinhole aperture in PH Verify the beam appears well cen tered on the pinhole Placing an aperture in the beam path reduces the beam size thus allowing more accurate overlap of the pump and HeNe beams in the subsequent steps f Adjust PO TM to overlap the pump and HeNe laser beams at a location just
33. upper and horizontal lower alignment knobs for directing the beam PO RM power oscillator routing mirror provides adjustment to align the incoming beam from PO TM and direct it to PO RM The mirror is spring loaded against 3 balls for repeatability after removal There are ver tical upper and horizontal lower alignment knobs for directing the beam Two screws can be loosened to move the optic vertically and 2 screws fasten the mount to the base plate PO RM power oscillator routing mirror provides adjustment to align the incoming beam from PO TM and direct it to the positive lens PO PL of the power oscillator telescope The mirror is spring loaded against 3 balls for repeatability after removal There are vertical upper and horizontal lower alignment knobs for directing the beam Two screws can be loos ened to move the optic vertically and 2 screws fasten the mount to the base plate PO Telescope is made up of the PO PL and PO NL described below and is used to set the diameter size of the beam PO PL power oscillator positive lens is the input end of the PO tele scope see above It is mounted on a spring loaded slide and a micrometer provides fine adjustment for setting the separation between the two lenses Although the lens can be cleaned in place it can be removed by removing the 4 screws of the retaining ring with an Allen ball driver and removing the lens with the retaining ring The lens is sprin
34. 355 nm Figure 5 10 Placement of Pick off Prism for Pump Collimation b 5 16 Place a pick off prism in the long pulse beam path between MO TM and MO TM Figure 5 10 It may be necessary to remove MO TMs Orient the prism so the long pulse beam is directed through the output port in front of PH 3 Place a beam dump in the pump beam path approximately 0 5 m from the MOPO HF Adjust the spacing between the positive and negative lenses so the beam appears nearly collimated but slightly diverging in LONG PULSE mode Perform a rough estimate of collimation by viewing the pump beam at two separate locations along the beam line The beam may be viewed at a location just past the negative lens and also in front of the beam dump Since the beam may have more convergence character when run in Q SWITCH mode due to thermal lensing in the YAG rods we rec ommend the negative and positive lens displacement be adjusted so the beam appears slightly divergent Warning W Note g Installation and Alignment If the beam is converging it can cause damage to the optical compo nents Therefore be sure the LONG PULSE beam is diverging initially It should be approximately 1 mm larger at the beam dump than at the neg ative lens location Place PH back onto its dowel pins Make the necessary horizontal and or vertical adjustments to MO PL to re center the beam onto the center of PH Remove PH Verify the l
35. American National Standards Institute ANSI 11 West 42 Street New York NY 10036 Tel 212 642 4900 Occupational Safety and Health Administration Publication 8 1 7 U S Department of Labor 200 Constitution Avenue N W Room N3647 Washington DC 20210 Tel 202 693 1999 A Guide for Control of Laser Hazards 4th Edition Publication 0165 American Conference of Governmental and Industrial Hygienists ACGIH 1330 Kemper Meadow Drive Cincinnati OH 45240 Tel 513 742 2020 Internet www acgih org home htm Laser Institute of America 13501 Ingenuity Drive Suite 128 Orlando FL 32826 Tel 800 345 2737 Internet www laserinstitute org Compliance Engineering 70 Codman Hill Road Boxborough MA 01719 Tel 978 635 8580 International Electrotechnical Commission Journal of the European Communities EN60825 1 TR3 Ed 1 0 Laser Safety Measurement and Instrumentation IEC 309 Plug Outlet and Socket Coupler for Industrial Uses Tel 41 22 919 0211 Fax 41 22 919 0300 Internet http ftp iec c h Cenelec European Committee for Electrotechnical Standardization Central Secretariat rue de Stassart 35 B 1050 Brussels Document Center 1504 Industrial Way Unit 9 Belmont CA 94002 4044 Tel 415 591 7600 Quanta Ray MOPO HF Optical Parametric Oscillator Equipment and Training 2 12 Laser Safety Guide Laser Institute of America 12424 Research Parkway Suite 125 Orlando FL 32826 Tel 407
36. Connector Switch Future Accessories e SYNG e O AUTOTRACK 115 230V 60 50Hz 5 0 3 0A E eJ Sine Drive Fan Q Switch Autotrack Connector to MOPO Sync Connector Connector to MOPO Figure 4 4 The Digital Controller Back Panel On Off POWER switch turns on and off the MOPO HF digital controller SINE DRIVE MOTOR connector provides connection to the sine drive motor in the MOPO HF Power cord connector provides connection for the power cord Warning W Controls Indicators and Connections Voltage selector provides selection between 115 and 220 Vac Verify this switch is set to the proper position before turning on your system for the first time If not properly set damage not covered by your warranty may occur to the controller and to various other voltage sensi tive components in the MOPO HF Optional FDO interface connector not shown in figure provides con nection to the FDO interface on the side panel of the MOPO HF for con trolling the frequency doubler option Refer to the MOPO HF FDO User s Manual for connection information Optional RS 232 TEEE 488 connectors not shown in figure provide connection to a remote control device for serial parallel control of the sys tem Refer to Chapter 6 Operation The Remote Menu for information on using these int
37. Press this button to select it then press it repeatedly to select the digit you wish to change and use the up down buttons to set its numerical value Press the button again to move to the next digit etc F BEGIN XXXX sets the beginning scan wavelength The MOPO HF beginning wavelength can be any number from 440 to lt 1830 nm The MOPO HF FDO beginning wavelength can be any number from 220 to lt 450 nm Press this button to select it then press it repeatedly to select the digit you wish to change and use the up down buttons to set its numerical value Press the button again to move to the next digit etc F4 END XXXX sets the end scan wavelength The MOPO HF end wave length can be any number from gt 440 to 1830 nm The MOPO HF FDO end wavelength can be any number from gt 220 to 450 nm Press this button The Setup2 Menu Operation to select it then press it repeatedly to select the digit you wish to change and use the up down buttons to set its numerical value Press the button again to move to the next digit etc F4 INCR indicates the system is set for an incremental scan The incre ment scan size between dwells is displayed in nanometers below INCR This mode is selected by setting SHOTS to 1 or greater A Setting of 07 sets the system to continuous scan CONT see below F CONT indicates the system is set for a continuous non incremental scan It is selected by setting the SHOTS parameter to
38. Ray MOPO HF Optical Parametric Oscillator previously selected These keys are referred to throughout this manual as function keys 1 through 5 F 4 Use the two up down arrow keys up down buttons to the right of the dis play either to change the numerical value inside a highlighted box on the display or to scroll through the various selections Menu Buttons Status Display Panel Up Down Buttons ATE OPERATE READY ser 500 000 SETUP MONITOR1 1220 814nm GOTO START MOVE RECALL SAVE SCAN 0 0 MONITOR M Fs Fo Fa Fy Fs Soft Key Function Buttons Figure 6 1 Initial configuration of the electronics panel The SSS Select Scroll Set Procedure 6 6 When operating the MOPO HF FDO use the select scroll set or SSS process to select an operation scroll though various options upon which to operate or to change the value of the selected operation and then set that value or option to lock it in To do this press the appropriate function key button to select the type of operation to be performed then use the up down buttons to scroll through the options or values then set that selection to lock it in by pressing and holding in the original select button until it beeps For example if you wanted to Y shift the calibration
39. SCAN parameters can be saved via remote com mand B 5 Quanta Ray MOPO HF Optical Parametric Oscillator Initialization After turning on the MOPO HF controller and selecting either RS 232 or IEEE 488 control initialize the computer interface as outlined below Procedure to Initialize the Interface Verification Test 1 If the IEEE 488 interface is used send the Select Device Clear bus command Refer to the instruction manual for your computer s GPIB interface card for specific details on how to execute a Select Device Clear command 2 Next whether the GPIB or RS 232 interface is used send a null string to the MOPO HF Written in the BASIC programming language this statement would look like PRINT 1 After the interface is initialized the MOPO HF interface hardware and data input buffer are reset Proceed with the communications link verifica tion test The communications link between your computer and the MOPO HF con troller is easily and quickly tested Simply send the query message to request the controller to send back a device identification message 1 Send this query message to the controller IDN 1 Receive this device identification message back QUANTA RAY MOPO HF V2 06 NOTE Refer to the Command and Query Messages section later in this appendix for more information about the IDN message The communications link is fully functional when the device identification message is received from the
40. Setting up continuous scan of signal range PRINT TotalLoops TotalLoops MultiLoop multiloop PRIN VK KK KKK KKK KKK KEK KK KKK KEK KKK KKK KKK KKK KKK KKK KKK Ck ck ck Ck ck ck ck ck ck ck Ck ko ck ck KKK KK ko ko A x Y Test scanning through signal range continuous This scan involves the crystal switch and should provide adequate torture of the system ScanBegin 220 multiloop Start at 220 000 nm ScanEnd 270 multiloop Stop at 270 000 nm Rate 1 100 picometers second Shots 0 Continuous scan scans 2 Make two passes PRINT 1 source begin ScanBegin PRINT 1 source end ScanEnd PRINT 1 source rate Rate PRINT 1 source shots Shots PRINT 1 source scans scans CONTINUOUS SCAN SETUP VERIFICATION GOSUB ReadSetup faultflag 0 IF Responsel lt gt ScanBegin THEN faultflag 1 IF Response2 lt gt ScanEnd THEN faultflag 1 IF Response3 lt gt Rate THEN faultflag 1 IF Response4 lt gt Shots THEN faultflag IF Response5 lt gt scans THEN faultflag PRINT PRINT Continuous Scan Setup multiloop multiloop of multiloopmax NS PRINT TotalLoops TotalLoops Quanta Ray MOPO HF Optical Parametric Oscillator PRINTIS SSeS poss See 5575 PRINT Parameter Sent Received PRINT
41. TM to center the reference beam on PH b Adjust R TM to center the reference beam on the installation pin hole PH which is located just before MO BBHR i Do not yet fasten R TM to the table surface ii Manually rotate R TM so the beam is directed through PH 3 111 If the beam is to the right of pinhole aperture PH move R TM toward the PO side of the MOPO HF and redirect the beam through PH z If the beam is to the left of PH move R TM in the opposite direction iv Repeat the above steps until the beam is nominally centered in the two pinholes v Fasten R TM to the optical table Caution Do not move or adjust the installation pinhole mount PH as it pre serves the calibration alignment established at the factory c Iterate Steps a and b until the beam is centered through the two pinholes Remove the pinhole aperture from the PH mount 7 Place the pinhole aperture on the other side of the PH 4 mount so the flat side of the aperture faces the BBO crystal This allows the reference beam retroreflections to be viewed on the flat side of the aperture during subsequent stages of the alignment proce dure 8 Remove MO BBHR Attach it to one of the available 10 32 holes on the base plate Make sure that it does not interfere with the HeNe beam 9 Remove the trigger cable from the Q SWITCH output port on the power supply and attach it to LAMP SYNC Quanta Ray MOPO HF Optical Parametric O
42. TRACK b Press and hold the MOPO button until it beeps to activate your selection From the Setup menu verify that 440 and 690 nm are entered for the begin and end wavelength scan values if you have performed the pre vious three procedures or set them to the scan range of interest This routine can take quite a while to run depending on the size of the scan range Set DEVICE to OPO a From the Setup2 menu press the DEVICE button then use the up down buttons to scroll to OPO b Press and hold the DEVICE button until it beeps to activate your selection Select the OPO_AUTO method to write this table a Press the METHOD button then use the up down buttons to scroll to OPO_AUTO b Press the METHOD button until it beeps to activate the selection and to move the system to the begin wavelength A menu will appear that displays TRACK CALIB and the automatic table writing routine will begin Upon completion a message is displayed that indicates calibration successful the ending wavelength and that the data was saved If the calibration is unsuccessful the message will say calibration unsuc cessful the wavelength at which the auto calibration routine stopped and that the data up to that point was saved The auto routine aborts when there is not enough light to make a solid measurement To continue the table writing routine you need to bring the system back within parameters for automatic table writin
43. They do not compose a complete program Refer to the sample program in the next section to see how these program state ments can be used in a complete and executable program PRINT 1 idn Read MOPO FDO ID message MopoID INPUTS 1 PRINT MopoID GOTO OPERATION PRINT 1 source goto 250 000 Set GOTO WL to 250nm PRINT 1 exegoto Execute GOTO operation Quanta Ray MOPO HF Optical Parametric Oscillator ScanBegin 255 Start at 255 000 nm ScanEnd 260 Stop at 260 000 nm Rate 1 100 picometers second Shots 0 Continuous scan Scans 2 Make two passes PRINT 1 source begin ScanBegin PRINT 1 source end ScanEnd PRINT 1 source rate Rate PRINT 1 source shots Shots PRINT 1 source scans Scans ScanBegin 300 Start at 300 000 nm ScanEnd 310 Stop at 310 000 nm Increment 2 5 2 5 nanometer steps Shots 100 100 shots at each WL Scans 3 Make thr passes PRINT 1 source begin ScanBegin PRINT 1 source end ScanEnd PRINT 1 source incr Increment PRINT 1 source shots Shots PRINT 1 source scans Scans PRINT 1 source begin GOSUB ReadData PRINT 1 source end GOSUB ReadData PRINT 1 source rate GOSUB ReadData PRINT 1 source shots GOSU
44. W Warning W Warning W Epson Plain gray card with black edge trim Latch retains battery Battery CR2025 Epson One side white opposite side light blue Latch retains battery Battery CR2025 Epson One side green brown copper opposite side brown Latch retains battery Battery BR2325 Panasonic BN 512HMC Gray and green with gray edge trim Screw retains battery Battery BR2325 The idea is simple leave the card in the controller and with the controller on replace the battery while the controller supplies power to the card While performing this procedure Do not turn off the power to the controller Do not remove the card There are two types of battery holders One type uses a small screw that secures the battery and holder in the card The other type uses a sliding latch to secure the battery holder Figure 1 shows memory cards from Mit subishi Panasonic and Epson Note the Epson card shown is the most common and is the first Epson type listed above and has no labeling Note the write protect slide on each unit Do not confuse this slide with the retaining latch on the Epson cards These cards must NOT be write protected or the system will not operate properly The Mitsubishi and Epson cards have battery holders which pull the battery out when they are removed The Panasonic card simply has an end cap to keep it from falling out The battery must be pulled out separately The batt
45. centered in PO TM Figure 5 23 If it is not adjust the position of the mirror mount as necessary The PO TM base plate should be roughly in the middle of its range of travel This will allow necessary room for the pump to be directed by the mount and through the output port for diagnostic purposes Perform the following steps for proper height adjustment a Place the pinhole aperture in front of PO TM b Adjust the PO TM to center the 355 nm pump beam on the pin hole c Remove the aperture d Adjust the PO TM horizontal so that the beam is to the left of the center of the PO TM optic Figure 5 23 Po o M as sse Ea Power Oscillator E E Reference Beam Pump In To MO Master Oscillator Long Pulse Figure 5 23 Overlap of HeNe Reference and Pump Beam for Power Oscillator 5 Place the pinhole aperture in front of PO TMz Adjust the PO TM to center the beam on the pinhole Remove the aperture to verify the beam is well centered on the optic Use a business card to locate the beam in front of PO RM Adjust PO TM to center the beam on the optic Place pinhole apertures on the appropriate dowel pins at PH and PH Adjust PO TM to roughly center the beam onto PH Align pump beam to PH and PH apertures a Place a pinhole aperture into PH Verify the beam is well centered the aperture PH reduces the beam diameter thus allowing more accurate alignment to the pinholes in the following steps b Adjust PO TM
46. controller Although the crystal rotates the entry and exit beam angles remain constant The entry beam comes from MO TM and is directed toward MO TMs There are no other adjustments on the crystal mount MO TM master oscillator turning mirror routes the beam from the crys tal to MO TM and MO BBHR Although the mirror can be cleaned in place 1t can be removed by using an Allen ball driver to loosen the 3 D cams that hold it in place then turning the cams to release the mirror The optic is wedged so there is a set orientation but there are no markings on the mirror for orientation Orientation is set during the alignment procedure It is spring loaded against 3 balls for repeatable seating There are vertical lower and horizontal upper alignment knobs for directing the beam Quanta Ray MOPO HF Optical Parametric Oscillator 4 4 Warning W Warning W MO BBHR master oscillator high reflector reflects the beam back through MO TM the crystal MO TM and to the grating The mount is fas tened to the base plate by two screws and the mount is slotted so it can be moved forward and backward Although the mirror can be cleaned in place 1t can be removed by removing 4 screws of the retaining ring with an Allen ball driver and removing the mirror with the retaining ring Two screws can be loosened for vertical adjustment The optic is flat so there is no set ori entation and it is spring loaded against 3 balls for repeatab
47. corresponding position value to a temporary user table and to move the crystal to the next wave length point for that table writing method b In like manner continue to optimize the position of the crystal at each point until all points for that method have position values c When the last value is written the CONT button changes to SAVE To save the values just obtained to the user table press and hold the SAVE button until it beeps If you decide not to save these values press the ABORT button a momentary press to allow the previous values to remain active If before or after the table is written you instead decide to start from scratch and load the theoretical values this will delete all your user values refer to Reloading the Theoretical Table Values below for instructions otherwise skip to the Lagrangian Table Writing Proce dure to continue enhancing your new table Reloading the Theoretical Table Values Caution W If tables have been previously written for the system this procedure will delete them Perform this procedure only if a prior table has NOT been written or 1f the current table is no longer valid e g there has been a loss of table data data corruption has occurred a grating re calibration has been completed or there has been a movement or realignment of the crystals To load the theoretical factory values for a fresh start perform the follow ing note these are not the va
48. direction of walk off is away from the optic axis of the crystal The steps below outline the set up and procedure for determination of the orientation of the optical axis based on this effect 1 Place a piece of lined paper on a flat surface 2 Hold the crystal approximately 25 mm 1 in from the paper in order to view one of the lines through the crystal 3 With the line passing through the short axis of the crystal aperture you should see a double image of the line Figure A 1 Polarizing Film Polarizing Film Transmission Transmission AXIS BBO Crystal Axis BBO Crystal Line ona piece of paper Top View Figure A 1 Viewing the double image through the crystal 4 Place a piece of sheet polarizer material on the paper with the trans mission axis perpendicular to the lines as shown 5 View one of the lines through the crystal at the edge of the polarizer where the lined paper is exposed 6 The line passing through the polarizer and crystal should be displaced either above or below the line on the paper 7 Since the polarized light walks away from the optic axis the following two situations can exist as shown in Figure A 2 A 1 Quanta Ray MOPO HF Optical Parametric Oscillator Refleg Line Light R ay Sc from Li BBO Xtal P Optic Axis BBO Xtal Viewer Figure A 2 The light walking away from the optical axis A 2 CASE I If the line p
49. execute goto recall parameter setting save parameters to file number x move forward um move backward um micro move forward 2 usteps micro move backward 2 usteps move forward 0 01 cm move backward 0 01 cm set mode to micro or standard resolution set to nm or cm enable closed loop tracking disable closed loop tracking enable track time out write master oscillator crystal table abort master oscillator crystal table writing operation to write a value if allowed to query a value if allowed Clear all IEEE 488 2 registers Query the ESR register ESR Query is a destructive read Query only system ID string Operation complete command or query Command only system reset Set or query the STB mask register set or quiry the ESE register Query only the IEEE 488 2 status byte Command system self test IEEE 488 2 wait command MOPO Implementation of the status byte A query of the status byte can be used to determine when a measurement should be made bit 7 stable lock bit set after successful track time out bit 6 IEEE 488 2 SRQ bit bit 5 IEEE 488 2 ESB bit bit 4 IEEE 488 2 MAV bit bit 3 exec bit operation goto for example in progress bit 2 move bit system is moving bit 1 lock bit active tracking enabled and successful bit O dwell bit at wavelength during incremental scan Quanta Ray MOPO HF Optical Parametric Oscillator Installation RS 232 C Interface IEEE 488 Interface
50. hereby declare that the equipment specified above con forms to the above Directives and Standards neo on Steve Sheng Vice President and General Manager Spectra Physics Inc Scientific and Industrial Systems December 31 1995 2 9 Quanta Ray MOPO HF Optical Parametric Oscillator CE Declaration of Conformity 2 10 We Spectra Physics Inc Scientific and Industrial Systems 1330 Terra Bella Avenue P O Box 7013 Mountain View CA 94039 7013 United States of America declare under sole responsibility that the Quanta Ray MOPO HF series Pulsed Optical Parametric Oscillators with digital controller meets the intent of Directive 73 23 EEC the Low Voltage directive Compliance was demonstrated to the following specifications as listed in the official Journal of the European Communities EN 61010 1 1993 Safety Requirements for Electrical Equipment for Measurement Control and Laboratory use EN 60825 1 1993 Safety for Laser Products I the undersigned hereby declare that the equipment specified above con forms to the above Directives and Standards pw Steve Sheng Vice President and General Manager Spectra Physics Inc Scientific and Industrial Systems January 1 1997 Laser Safety Sources for Additional Information The following are some sources for additional information on laser safety standards safety equipment and training Laser Safety Standards Safe Use of Lasers Z136 1 1993
51. it can be removed by removing 4 screws of the retaining ring with an Allen ball driver and removing the mirror with the retaining ring There are vertical top and horizontal side alignment knobs for directing the beam Two screws can be loosened to move the optic vertically and 2 screws fasten the mount to the base plate VDC visible dichroic transmits any residual visible wavelengths from the output beam from VDC then directs the beam out of the MOPO HF enclosure Although the mirror can be cleaned in place it can be removed by removing 4 screws of the retaining ring with an Allen ball driver and removing the mirror with the retaining ring There are vertical top and horizontal side alignment knobs for directing the beam Two screws can be loosened to move the optic vertically and 2 screws fasten the mount to the base plate HW half wave plate used for attenuating power to the PO by rotating it PO TM power oscillator turning mirror provides adjustment to align the incoming beam from UVBS and direct it to PO TM The mount is fas tened to the base plate by two screws and the mount is slotted so it can be moved forward and backward Although the mirror can be cleaned in place it can be removed by removing 4 screws of the retaining ring with an Allen ball driver and removing the mirror with the retaining ring The optic is flat so there is no set orientation and it is spring loaded against 3 balls for repeatability a
52. maintenance or service of your laser avoid unnecessary exposure to laser or collateral radiation that exceeds the accessible emission limits listed in Performance Standards for Laser Prod ucts United States Code of Federal Regulations 21CFR1040 10 d Laser Safety Follow the instructions contained in this manual to ensure proper installa tion and safe operation of your laser Focused Back Reflection Safety Focused back reflections of even a small percentage of the output energy of any Pro series laser can destroy its optical components To illustrate con sider an uncoated convex lens which reflects about 4 of the energy inci dent on each of its surfaces While the reflection off the first surface diverges harmlessly the reflection off the second surface focuses and the power density at the point of focus is high enough to destroy the Q switch Nd YAG rod and output coupler of the laser Even anti reflection coated optics can reflect enough energy to damage optical components of the laser To avoid damage to your laser minimize back reflections of its output beam and where they are unavoidable direct them away from the optical axis Warning This Quanta Ray warranty does not cover damage caused by focused back reflections Maintenance Necessary to Keep this Laser Product in Compliance with Center for Devices and Radiological Health CDRH Regulations This laser product complies with Title 21 of the United
53. negative lens S NL to center the expanding beam on PH and PH Center the leakage light from PH onto PH Place the 1 in optic barrel that contains the positive lens back onto the seed telescope assembly Using 16 in hex wrench adjust the x and y position of the positive lens S PL to center the expanding beam on PH and PH Center the leakage light from PH onto PH Remove the PH and PH apertures Adjust the distance between the positive lens and negative lenses z position adjustment to collimate the light that is coupled through the Note Note Installation and Alignment cavity Since the telescope expands the seed beam up to 6 times its ini tial size the light will overfill the clear aperture of the crystal compen sator Thus the expanded seed light will have a rectangular appearance Initial collimation is attained by making the size of the rectangular cone of light roughly the same at PH and PH 11 Place PH and PH back onto the base plate Verify the leakage light from PH is centered onto PH Method B PO has not been previously aligned 1 Change to LONG PULSE mode 2 Place the top half of the seed telescope assembly back onto its base assembly There should be no lenses in the S PL or S NL mounts 3 Use a 16 in hex wrench to remove the 1 in optic barrel that contains the positive lens 4 Change to Q SWITCH mode Oscillation in the MO should resume 5 Loosen the seed
54. off Master Oscillator Prism Grating MO TM4 MO TMs MO BBHR Pump In 355 nm MO Output To Power Meter or Screen Target Figure 5 14 Placement for pick off prism assembly for master oscilla tor output energy measurement 3 Remove the MO BBHR from its alignment position and place it back in its standard position Figure 5 9 Note In the following procedures the MO output must be suppressed several times This may be conveniently done by placing a business card over MO BBHR to stop oscillation To have room to do this leave at least a 2 3 mm space between MO BBHR and MO TM 5 20 Installation and Alignment a Bend the short side of a business card so the bent portion is approximately 10 mm wide b To see if it works hang the card over the front side of the MO BBHR optic Figure 5 15 Business Card cmm Figure 5 15 A business card folded and hung over the MO BBHR c Remove the card 4 Align the retro reflected reference beam which originates from the backside of MO BBHR to a position approximately 2 mm to the left of the pinhole aperture in PH 3 Due to the wedge in the MO BBHR optic a series of retro reflected spots are produced It is important these reflections be in the horizontal plane If this is not the case rotate the optic in the mount to achieve the correct orientation The primary reflection from the optical coating is the brightest The
55. or m Installation and Alignment Optimizing MOPO Operation Fine Tuning MOPO Collimation Achieving well collimated pump signal and idler beams is important to achieve best linewidth and beam propagation characteristics Note Use this procedure only if the signal and idler mode characteristics are not suitable 1 Make a minor change about 1 mm to the PO telescope lens spacing in an arbitrary direction using the procedures outlined in the previous section Verify the pump still appears reasonably collimated Check to see if the signal and idler beam collimation has improved 2 Make minor changes to seed beam divergence e g 1 mm changes in S PL position Check to see if the signal and idler beam collimation has improved 3 Iterate Steps 1 2 until the signal and idler beam collimation is opti mized Optimizing MOPO Stability 1 Passive non scanning stability a Direct the MOPO HF output into a power meter Verify it is at a fixed wavelength e g 500 nm b While observing the power meter reading carefully apply a lifting pressure to each corner of the base plate c If the stability of the output improves while lifting a particular cor ner perform the following steps i Use the s in wrench to make a very slight adjustment on the foot belonging to the corner ii Adjust the foot to optimize the stability iii Do not tighten the lock nut 2 Scanning stability a Perform an x adjustment o
56. safety Condition or action may present an electrical hazard to personal safety Warning Condition or action may cause damage to equipment ESD ment Caution Note Condition or action may cause poor performance or error Text describes exceptional circumstances or makes a special refer ence Don t Do not touch Touch Warning Y Action may cause electrostatic discharge and cause damage to equip 9 Appropriate laser safety eyewear should be worn during this opera Eyewear y tion Required Refer to the enclosed documents and manual before operating or using this device xiii Standard Units The following units abbreviations and prefixes are used in this Spectra Physics manual Quantity Unit Abbreviation mass kilogram kg length meter m time second S frequency hertz Hz force newton N energy joule J power watt W electric current ampere A electric charge coulomb C electric potential volt V resistance ohm Q inductance henry H magnetic flux weber Wb magnetic flux density tesla T luminous intensity candela cd temperature celcius C pressure pascal Pa capacitance farad F angle radian rad Prefixes tera 107 T deci 10 d nano 10 n giga 10 G centi 10 c pico 101 p mega 10 M mill 10 m femto 10 f kilo 10 k micro 109 u atto 10 a XV Unpacking and Inspection Unpacking Your MOPO HF Your MOPO HF system was packed with great care and its conta
57. seeding requires that the seed pulse arrive in the crystal before the pump pulse This requirement is satisfied by a suitable optical delay line for the pump beam The seeding process is also enhanced when the oscilla tor is running near threshold This is realized in the power oscillator with an appropriate choice of pump energy and spot size the BBO crystal These factors allow the seed radiation to overwhelm the quantum noise induced parametric generation in the crystal resulting in a well seeded operation Dichroic Beam Separation The output beam from the power oscillator contains the collinear signal and idler waves which need to be separated for most applications Conse quently all MOPO HF systems contain a broadband dichroic pair to sepa rate the two beams The use of two dichroic optics ensures gt 97 spectrally pure beams Figure 3 8 The final outputs are parallel and are spaced two inches apart By designing the oscillators to be singly resonant over the signal wave length range a single set of broadband optics allow continuous tuning from 450 to 1680 nm This means that no mirror change or realignment is neces sary when scanning across the visible or near IR spectrum OC BS VDC COMP gt Idler Beam Out Signal Beam Out VDC Figure 3 8 Dichroic Beam Separation Angle is Everything in OPOs The process by which gain is derived in an optical parametric oscillator is fundamentally differen
58. telescope base plate screws Slide the telescope base laterally to center the seed beam horizontally in the S NL mount coarse x axis adjustment The beam should also be approximately centered on the S PL barrel mount Tighten the telescope base plate screws 7 Change to LONG PULSE mode 8 Mount S PL a Remove the S PL optic barrel b Remove the retaining spring c Insert the 75 mm fl optic d Insert the retaining spring e Set the S PL assembly aside 9 Mount the 12 mm fl lens in the S NL mount 10 Change to Q SWITCH mode Oscillation in the MO should resume 11 Using a 16 in hex wrench adjust the x and y position of the negative lens S NL TO center the expanding beam on PH and PH Center the leakage light from PH onto PH If the intensity of the seed beam on PH is too low perform one of the following steps a Turn out the room lights or 5 41 Quanta Ray MOPO HF Optical Parametric Oscillator 12 13 14 13 16 b Tune the MO wavelength 5 10 nm around 500 nm to find the transmission peak for the PO BBHR coating The peak may be veri fied by observing maximum brightness of the seed light on PHg The transmission peak is usually in the 500 505 nm region The following procedure may be used to assess location of this peak i Write a table using MO AUTO from 495 505 nm ii Perform a series of GOTOs in 1 nm increments from 495 505 nm Note if the peak cannot be fou
59. the beam Two screws can be loos ened to move the optic vertically and 2 screws fasten the mount to the base plate Slotted holes allow the mount to be moved forward and backward in the beam PO BBO crystal power oscillator crystal is the nonlinear wavelength tuning element on the power oscillator side A single screw holds it in its holder and the holding arm rotates the crystal via a motor driven by the MOPO controller Although the crystal rotates the entry and exit beam angles remain constant The entry beam comes from PO TM and is directed toward PO TMg There are no other adjustments on the crystal mount PO TM power oscillator turning mirror allows the output beam to pass through but turns a residual beam from the PO BBO crystal and directs it to turning mirror PO TM and on to the beam dump MBD The optic is wedged so there is a set orientation but there are no markings on the mirror for orientation This rotation setting is set during the alignment procedure Although the mirror can be cleaned in place it can be removed or rotated using an Allen ball driver to loosen the 3 D cams that hold it in place Quanta Ray MOPO HF Optical Parametric Oscillator 4 6 Loosen to rotate the mirror turn the cams to release the mirror you may have to actually remove one of the cams in order to remove the optic The mount is spring loaded against 3 balls for repeatable seating There are ver tical upper and horizontal lower ali
60. the main portion of the output coupler mount so that oscillation in the PO is terminated however the oscillator may still be partially aligned Thus when the Note g A hex wrench less than g in thick may terminate unseeded operation oscillator is seeded the operating characteristics may be more like that of an oscillator than an amplifier 5 5 42 Change to Q SWITCH mode Oscillation in the MO should resume Installation and Alignment Wait several minutes for the MO output power to stabilize Adjust the PO crystal until amplification is observed a Access the crystal device menu b Press the PO XTAL softkey to activate it c Access the table writing options softkey Toggle through the menu options until Y_SHIFT is obtained Press and hold down the softkey to activate the option d Press the up and down arrow soft keys until parametric ampli fication is attained Settle on the crystal position that results in the brightest output Parametric amplification may be verified by observing idler behind VDC using an IR card e Press the CONT softkey A beep should be heard and the softkey label should change to SAVE Press and hold the softkey down until a beep is heard to store the new table values The signal and pump beams should also be visible on the IR card behind VDC Use the x and y adjustments on S PL to overlap the sig nal idler and pump beams Part Ill Conversion to Unseeded OPO
61. warning labels would be appropriate for use as entry warning signs EN60825 1 ANSI 4 3 10 1 2 0 a aa aa ea aa aa aaa aaa ee 2 2 Figure 2 2 Optical Beam Dump BD 5 aaa aa ea aa aa aaa aa aa aa aaa aaa 2 2 Figure 2 3 CE CDRH Radiation Control Drawing a eaaa aaa 2 5 Figure 2 4 CE CDRH Warning Labels oococcccccccoo re 2 6 Figure 3 1 Frequency mixing to generate the third harmonic of Nd YAG oooccocccooo ooo 3 1 Figure 3 2 Parametric Amplification to Generate Tunable Output from 450 nm to Beyond 1700 nm 3 2 Figure 3 3 Theoretical signal and idler Output wavelengths for 355 nm Pump 3 2 Figure 3 4 The MOPO HF Master Oscillator uses a Grazing Incidence geometry to produce sub 0 075 cm 1 mean linewidths The wave length centered at the peak of the BBO gain bandwidth As is reflected back into the cavity while those at the edge of the gain bandwidth walk out of the cavity and do not oscillate leeren 3 4 Figure 3 5 Pump pulse depletion and resulting parametric output pulse 3 5 Figure 3 6 Schematic of an Unstable Resonator Design used in the MOPO HF Series 3 5 Figure 3 7 Power oscillator cavity geometry Illustration shows separation of signal and idler output beams with broadband dichroic mirrors llle 3 6 Figure 3 8 Dichroic Beam Separation a a tenes 3 7 Figure 3 9 Collinear a and noncollinear b phase matching
62. wedge on the optic should be oriented so that the primary reflection is the second one from the right as shown in Figure 5 16 Use a card in order to view the weaker retroreflections turning the lights out may help Primary reflection located 2 mm to the left of the pinhole 0000 Pinhole Series of reflected spots Figure 5 16 Retroreflections from the MO BBHR shown in the correct horizontal orientation 5 Verify the system is set to 500 nm 6 Change to Q SWITCH mode 7 Use one of the procedures outlined in Appendix D to manually rotate the crystal until oscillation is attained 8 Important If oscillation is not observed turn off the PRO Series seeder To do this 5 21 Quanta Ray MOPO HF Optical Parametric Oscillator memo ao sp Change to LONG PULSE mode Turn off the seeder Change to Q SWITCH mode Manually adjust the crystal until oscillation is achieved Change to LONG PULSE mode Turn on the seeder Change to Q SWITCH mode Turning the seeder off results in multi mode output of the PRO Series pump source for the MOPO HF As a consequence the oscillation threshold for the MO is lowered and thus easier to achieve oscillation and to optimize it 9 Once oscillation has been confirmed perform a Y_SHIFT to the exist ing table at 500 nm a b j k Confirm the system is at 500 nm If necessary confirm the autotrack board control switch is in the computer posi
63. 0 510 nm wavelength range output energy is not in the desired range a different PO telescope Note If the may be required Seeding the Power Oscillator 5 38 To MOPD OC BS PH VDC S TP f N BBO COMP u U Po Z A SNL S PL PO PO TM PO TM lt lt TY BBHR ie 2 PH PH GRATING TUN MIR Figure 5 25 Seed Beam Alignment Installation and Alignment Seed Beam Alignment coarse alignment 1 2 3 4 10 11 12 13 14 15 16 17 18 Change to LONG PULSE mode Place S TP back onto the base plate Verify the top half of the seed telescope assembly has been removed Place a beam block in the pump beam path at a location before PO TM Do this by placing MBD over the dowel pins at PH This prevents the PO from oscillating during the procedures described below Verify a beam dump is approximately 2 m from the idler output port This allows the idler and leakage signal to be overlapped over suf ficiently large distances Place PH and PH back onto the MOPO HF base plate Verify the flat side of the apertures are facing the BBO crystal Allow oscillation in the MO to resume remove the business card from in front of MO BBHR The MO output should be directed onto S TP Figure 5 25 Change to Q SWITCH mode Oscillation in the MO should resume Adjust S TP to direct the seed beam onto the center of S TP Figure 5 2
64. 5 If necessary adjust the position of BS to direct the seed beam reflec tion into MOPD master oscillator detector Make sure the seed beam passes through the optic without clipping the sides of the mount Adjust the position of the detector in order to maximize the signal The S TP base plate is slotted to allow translation If necessary adjust the base plate position to the center of these slots Coarse overlap procedure a Rotate S TP to overlap the signal beam onto PH see Figure 5 25 b Note how far the leakage from PH is displaced from the PH aper ture c If necessary reposition the S TP mount e g choose a new pivot location and re rotate to assess how well the beam is centered on the two pinholes Repeat this step until overlap on the two pinholes is achieved Tighten the S TP base plate screws to fix the mount in position Adjust S TP to overlap the leakage signal beam on the PH pinhole aperture Adjust S TP to overlap the beam on the pinhole aperture PH Repeat steps 14 15 until overlapped is achieved at both locations The MO beam should pass through BS Optimize the signal level on MOPO HF using the following proce dure 5 39 Quanta Ray MOPO HF Optical Parametric Oscillator a Access the monitor menu on the MOPO HF controller b Note the signal levels on the MO monitor Maximize the signal level on the MO monitor by adjusting its posi tion so that the Fresnel reflections from BS
65. 550 mm PL CVX 0452 2090 Lens 500 mm PL CC 0452 2080 Lens 300 mm PL CVX 0449 2340 Lens 250 mm PL CVX 0448 8850 Lens 200 mm PL CVX 0448 8860 Lens 150 mm PL CVX 0448 8870 Lens 150 mm PL CC 0448 8880 Lens 100 mm PL CC 0448 8890 Grating 2700 Lines mm 0448 8760 Mirror Tuning MO 0448 8770 Absorber 0449 0490 Beam splitter 12 355 nm 1 5 in 0451 1170 Beam splitter 14 355 nm 1 5 in 0451 6440 Beam splitter 17 355 nm 1 5 in 0449 1100 Beam splitter 24 355 nm 1 5 in 0449 1110 Beam splitter 31 355 nm 1 5 in 0449 1120 Beam splitter 38 355 nm 1 5 in 0449 1130 Beam splitter 45 355 nm 1 5 in 0449 1140 Beam splitter 52 355 nm 1 5 in 0449 1150 Rt Angle Prism AR 355 nm 1 5 in 0449 1530 Enhanced High Reflector 0449 1650 8 5 Quanta Ray MOPO HF Optical Parametric Oscillator 8 6 Table 8 1 Replacement Parts Description Part Number Window AR 355 nm BBHR 100 cm CC PL Filter ND 0 1 Filter ND 1 Filter ND 3 Filter ND 10 Filter Band Pass 360 nm Filter Heat Absorbing Mounted Turning Prism AR 355 0449 1910 0449 2670 0449 4640 0449 4641 0449 4642 0449 4643 0449 4670 0449 4680 9800 0770 Chapter 9 Customer Service Warranty Customer Service At Spectra Physics we take great pride in the reliability of our products Considerable emphasis has been placed on controlled manufacturing meth ods and quality control throughout the manufactu
66. B ReadData PRINT 1 source scans GOSUB ReadData PRINT 1 source incr GOSUB ReadData The RS 232 IEEE 488 Interface MONITOR OPERATING STATUS PRINT 1 read wlen GOSUB ReadData PRINT 1 read count GOSUB ReadData PRINT 1 read power GOSUB ReadData Inputs None Outputs Responses ReadData Chars NewChar WHILE NewChar lt gt CHR 10 Loop until LF is receiving Response Chars Save all but the LF char WHILE EOF 1 WEND Wait for next char NewChar INPUTS 1 1 Input next char Chars Chars NewChars Combine all chars WEND RETURN Sample Programs The following programs are written in the Microsoft QuickBasic programming language They will run on any IBM PC compatible computer The first program sends messages to the MOPO HF through the RS 232 C serial communications port the second uses the optional GPIB IEEE 488 par allel interface NK KKK KE KKK KKK KEK KKK KK KEK KKK KKK KKK KKK KKK KKK ck ck ck Ck ck ck KKK ck ko ko KKK ko ko ko KK FDO 700 SERIES SAMPLE PROGRAM LIB 07 28 95 This program tests the RS232 doubler interface Max baud rate is 2400 NK KKK KKK KKK KK KKK KKK KE KKK KKK KKK KKK KKK KKK ck ck ck ck Ck ck KKK KK ck ko KAKAK ko ko ko KK CLS DoWaits 0 1 wait 5 seconds between many of the queries multiloopmax 50
67. BO crystal If necessary adjust the position of the pick off prism so that it intercepts this reflection Figure 5 11 5 17 Quanta Ray MOPO HF Optical Parametric Oscillator Pump in S Tuning q AA gt gt Long Pulse AJ Mirror mode of operation To PO Power Oscillator MO BBHR removed Master Oscillator Grating MO TM o MO TM PH PH BB J NA Senne oe d OLDER A EME m X X Reference X i Beam In b J m MO TM MO TM Alignment Card Figure 5 11 Overlap Location of HeNe Reference and Pump Beams b C Adjust the prism position so the first surface reflection from the HeNe beam is directed onto the inside of the MOPO HF lower cover approximately 5 cm to the right of the MO alignment port hole Using a pen or pencil mark 2 lines on a business card that are spaced 2 cm apart Figure 5 12 This will be referred to as the alignment card MOPO HF Chassis Output Side MO Porthole 2cm gt Reference MO Pump Beam Beam Alignment Card Figure 5 12 Overlap location for master oscillator overlap procedure d 5 18 Tape the alignment card to the inside of the MOPO HF chassis so the left most mark is overlapped with the first surface HeNe reflection Using a business card cut into a strip of approximately 10 mm locate the pump beam in between MO TM and the BBO crystal Be careful not to touch the
68. Daiwa Nakameguro Building 4 6 1 Nakameguro Meguro ku Tokyo 153 Telephone 81 3 3794 5511 Fax 81 3 3794 5510 Japan West Spectra Physics KK West Regional Office Nishi honmachi Solar Building 3 1 43 Nishi honmachi Nishi ku Osaka 550 0005 Telephone 81 6 4390 6770 Fax 81 6 4390 2760 e mail niwamuro O splasers co jp United Kingdom Telephone 44 1442 258100 United States and Export Countries Spectra Physics 1330 Terra Bella Avenue Mountain View CA 94043 Telephone 800 456 2552 Service or 800 SPL LASER Sales or 800 775 5273 Sales or 650 961 2550 Operator Fax 650 964 3584 e mail service O splasers com sales O splasers com Internet www spectra physics com And all European and Middle Eastern countries not included on this list And all non European or Middle Eastern countries not included on this list Quanta Ray MOPO HF Optical Parametric Oscillator 9 4 Appendix A Installing the BBO Crystal Due to cost and fragility only a qualified spectra physics service engineer should perform the crystal installation described below Determining the Orientation of the Optical Axis in the Crystal Since BBO is a birefringent crystal it exhibits a characteristic optical prop erty known as double refraction Polarized light passing through an appro priately oriented crystal may be observed to walk off its initial axis of entry Since BBO is a negative uniaxial crystal the
69. EOD E e ehh B 5 Saving Setup Parameters saa saa a a naati a a aaa al AN aa ag ehh B 5 IriitiallZatlon irte a be a ng Rede aa ole PEE bw PEA ol bene ed B 6 Procedure to Initialize the Interface 0 0 eae B 6 Verification Test soos sug ta yee e ee E ee EA B 6 MOPO FDO Firmware Revision a hrs B 6 Format and Syntax Rules is siue didexum da wh ee e epp PRI ESSE BB a dee ee bes B 7 FMA a hag Adah a tigen A E N eue orte Ge iubeas B 7 SMA San rM RPM B 7 Message Terminations uan sd oa ee hese meer EE v aD uc den RR PER EA B 7 Programming Examples Ser fee fe ad e ed e bebe hed eee d B 7 Sample Programs srar erre dBA one aa Beige Sey eae he Ee ET db EE B 9 CONNECHONS Aisa ee ee pales RT Mee Ee pha dasa aaa RAN A ui ae EE Giaa B 27 Appendix C Replacing the PCMCIA Card Battery lt lt lt C 1 Card Description Replacement Battery List liliis C 1 Procedure ensi eee EIE a IR ae A e i aeter Re Ee ees m d e e oo Green C 2 Appendix D Manually Controlling the Crystal Stage D 1 Appendix E Determining Telescope Lenses for the PO E 1 Appendix F Installing a Software Upgrade lll ss F 1 Notes Report Form Table of Contents List of Figures Figure 1 1 The Quanta Ray MOPO HF System ea eaaa eee 1 1 Figure 1 2 The Quanta Ray MOPO HF Digital Controller lille 1 2 Figure 2 1 These standard safety
70. Hg Adjust MO TM to center the portion of the beam that passes through PH onto the PH pinhole aperture f Iterate these two steps until the beam is centered through pinholes PH and PH g Verify PH is at its appropriate location 5 14 Warning W Installation and Alignment PHg is used to limit the size of the beam This is useful in the next alignment step Place the negative lens mount MO NL back in its appropriate loca tion in the pump beam line The beam should be in the approxi mate center of the lens Make the necessary horizontal and vertical adjustments of MO NL to direct the pump beam onto the center of pinhole PH Remove Pho Place the positive lens back into the MO PL mount The distance between the positive lens and the negative lens should be approxi mately the difference in absolute focal lengths of the two lenses For example the 2 5 reducing MO telescope typically consists of a 250 mm and a 100 mm focal length lens These lenses should be separated by approximately 250 100 150 mm In order to mini mize the chance of damage set the spacing initially about 10 mm closer This should result in a slightly diverging beam In this example the lenses should initially be set at 140 mm Make the necessary horizontal and vertical adjustments of MO PL to re direct the beam onto the center of PH i Loosen the mount Use a 32 in hex wrench to loosen the two screws on the front side of t
71. Installation 24 22 ed ee ee Se ee ee heed on SO ee ed ak Bal BA a ay A a g 5 1 Materials Needed 0 eh rn 5 1 Initial Setup iere a ea ea See ue Ba Ii we 5 2 Electronics and Controller Setup oooocccccco eee 5 6 A mE 5 7 Establish the Reference Beam for the Master Oscillator o oooooooooooooooo 5 7 Master Oscillator Overlap Procedure 0 000 cece teen ee 5 12 Attaining Oscillation in the Master Oscillator_ aaa tee 5 20 Optimize the Master Oscillator liiis s 5 22 Linewidth Measurement a e hr re mr 5 24 Establish Reference Beam for Power Oscillator_ eee eee 5 25 Power Oscillator Overlap Procedure 000 5 30 Attaining Oscillation in the Power Oscillator lieee eI 5 36 Seeding the Power Oscillator ccc rn 5 38 Optimizing Seed Beam Alignment 00000 eee 5 40 Part I Seed Telescope Alignment 00 cece ae 5 40 Part Il Seed beam alignment using an optical parametric amplifier OPA 00 cece RR rs 5 42 Part Ill Conversion to Unseeded OPO cee eee 5 43 Optimizing MOPO Operation cette 5 45 Fine Tuning MOPO Collimation ea e aaa ea Hun 5 45 Optimizing MOPO Stability a m rn 5 45 viii Table of Contents Chapter 6 Operalion lt lt lt suu eee na wu n at De De uc We au a 6 1 MOPO HF FDO Dos arid Don ts umi a east bide ed
72. MO Negative Lens S PL Seeder Positive Lens MO TM4 6 MO Turning Mirrors S TPy4 2 Seeder Turning Prisms oc Output Coupler UV BS Ultraviolet Beam Splitter PH1 46 Pin Holes VDC4 2 Visual Dichroics Figure 4 1 The MOPO HF Beam Path Quanta Ray MOPO HF Optical Parametric Oscillator External Controls Internal Controls Shutter there is none Because the MOPO HF is not a laser it does not have a shutter When you need to block the beam temporarily set the pump laser to Q SWITCH OFF Cover clamping screws 4 hold the cover securely in place One screw is located on each corner of the cover Foot height adjustments 4 provide a means to level the MOPO HF and to adjust its height to match that of the pump laser or target device The legs are large screws with swivel feet that can be screwed up and down from inside the laser head using an Allen driver Once the height adjust ment has been made a jam nut on each leg is tightened up against the chas sis to lock them in place Master Oscillator UV BS uv beam splitter divides the beam sending approximately 60 to 75 mJ to the master oscillator MO and the rest to the power oscillator PO The mount is fastened to the base plate by two screws Although the mirror can be cleaned in place it can be removed by unscrewing the bezel There are vertical top and horizontal side alignment knobs for directing the beam MBD mini beam dump absorbs the return MO beam that is refl
73. NAMES Mopo IF Mopo lt 0 THEN CALL GpibError IBFIND ERROR Clear MOPO GPIB interface CALL IBCLR Mopo F IBSTAS AND EERR THEN CALL GpibError IBCLR ERROR CLS DoWaits 0 multiloopmax 50 TotalLoops 0 Quanta Ray MOPO HF Optical Parametric Oscillator START OF MULTILOOP TotalLoop FOR multiloop 1 TO multiloopmax TotalLoops TotalLoops 1 CLS PRINT DOUBLER GPIB COMMUNICATIONS TEST AND DEMO PROGRAM PRINT multiLoop number multiloop of multiloopmax PRINT Total loops TotalLoops PRINT Expected QUANTA RAY MOPO HF 0 V2 06 Cmd IDN GOSUB WriteMopo GOSUB ReadMopo IF Expected lt gt MID Response 1 31 THEN PRINT GPIB communications error PRINT Response expected Expected ELSE PRINT GPIB okay END IF PRINT Response received Response PRINT REM GOTO ContinScanSetup GotoWL 450 multiloop Cmd source goto STRS GotoWL GOSUB WriteMopo Cmd exegoto GOSUB WriteMopo The RS 232 IEEE 488 Interface PRINT GOTO running PRIN PRINT Going to GotoWL PRIN Wavelength 0
74. NIA 94039 7013 MANUFACTURED MONTH MODEL THIS LASER PRODUCT COMPLIES WITH 21 CFR 1040 AS APPLICABLE MADE IN U S A Serial Number CDRH Compliance Label 7 CE Caution Label 10 CE Certification Label 8 115 230V 60 50Hz 5 0 3 0A 0451 7233 Input Line Voltage Label 11 Figure 2 4 CE CDRH Warning Labels 2 6 CE Danger Label 6 Spectra Physics Lasers 1330 TERRA BELLA AVENUE MOUNTAIN VIEW CALIF 94043 THIS PRODUCT IS MANUFACTURED UNDER ONE OR MORE OF THE FOLLOWING PATENTS 5 033 057 5 053 641 5 047 668 5 390 211 0448 8700 Patent Label 9 REPLACE THE BATTERY WITH THE SAME OR EQUIVALENT TYPE RECOMMENDED BY THE MANUFACTURER DISPOSE OF USED BATTERIES ACCORDING TO THE MANUFACTURER S INSTRUCTIONS Battery Replacement Label 12 Laser Safety Label Translations For safety the following translations are provided for non English speak ing personnel The number in parenthesis in the first column corresponds to the label number listed on the previous page Label French German Spanish Dutch Aperture Ouverture Laser Austritt von sichtbarer Por esta abertura se Vanuit dit apertuur Label Exposition Dan und unsictbarer emite radiacion laser wordt zichtbare en 1 gereuse Un Rayon Laserstrahlung nicht visible e invisible niet zichtbare laser nement laser visible dem Strahl aus evite l
75. OPEN COM2 2400 N 8 1 FOR RANDOM AS 1 TotalLoops 0 Quanta Ray MOPO HF Optical Parametric Oscillator TotalLoop FOR multiloop 1 TO multiloopmax ONS TEST AND DEMO PROGRAM multiloop of multiloopmax Clear MOPO input buffer TotalLoops TotalLoops 1 CLS PRINT MOPO SERIAL COMMUNICAT PRINT multiLoop number PRINT Total loops TotalLoops PRINT PRINT 1 VERIFICATION TEST PRINT 1 idn MopoID INPUT 35 1 PRINT MopoID GotoWL 448 multiloop PRINT 1 source goto GotoWL PRINT 1 exegoto PRINT GOTO running PRINT Wavelength 0 STB REM WHILE Wavelength lt gt GotoWL WHILE STB lt gt 0 PRINT 1 read wlen GOSUB readdata VAL responses Wavelength PRINT 1 stb GOSUB readdata STB PRINT PRINT VAL responses TotalLoops multiloop STB STB WEND ContinScanSetup v s go to idler extreme wavlength anything other than zero old style Wait for GOTO to finish wait for GOTO to finish read SCPI status byte multiloopmax Wavelength IF DoWaits THEN GOSUB WaitFiveSeconds Wavelength The RS 232 IEEE 488 Interface REM GOTO IncrScanSetup PRIN PRINT
76. PO TM 5 30 Figure 5 23 Overlap of HeNe Reference and Pump Beam for Power Oscillator 5 32 Figure 5 24 Power Oscillator Pick Off Prism Placement 000 cece eee eee 5 33 Figure 5 25 Seed Beam Alignment oooocccoccoo tees 5 38 Figure 6 1 Initial configuration of the electronics panel cee eee eee 6 6 Figure 6 2 The Operate Menu eee eee 6 11 Figure 6 3 The Operate2 Menu ea ea a aa a ea aa aaa eaaa aa eee 6 13 Figure 6 4 The Service Menu aa ea aa ea aa aa aaa aa aa aa aaa eaaa aaa 6 14 Figure 6 5 The Setup Menu pe ee Esth oie vee se aa BI NR Aa ees Sale da 6 15 Figure 6 6 The Setup2 Menu aa aa ea ea aa aaa eaaa aaa aa aa aa aa eaaa 6 17 Figure 6 7 The Remote Menu sasiki aaa Nan Ka Ka a KB aa ak a a a KG ak Kg ag m 6 21 Figure 6 8 Returning Local Control to the System aa a aaa en 6 22 Figure 6 9 Monitor Menu sisas ag aka a Ga BN KADA Kg a BAREK eee 6 23 Figure 6 10 Initiating a Scan a tees 6 25 Figure 6 11 Scan in Progress aaa saka a EEE cette ete 6 26 Figure 7 1 Lens Tissue Folded for Cleaning anaua aaea 7 2 Figure A 1 Viewing the double image through the crystal eee A 1 Figure A 2 The light walking away from the optical axis llle A 2 Figure A 3 Observing the master and power oscillator crystals 00000 eee eee eee A 2 Figure A 4 Determining the C ax
77. Quanta Ray MOPO HE Optical Parametric Oscillator User s Manual G Spectra Physics The Solid State Laser Company 1335 Terra Bella Avenue Mountain View CA 94043 Part Number 0000 2674 Rev C August 2002 Preface Thank you for purchasing the Spectra Physics Quanta Ray MOPO HF sys tem This manual contains information you need in order to safely install align operate maintain and service your MOPO HF optical parametric oscillator The system comprises two or three elements the MOPO HF head a digital controller and an optional Model FDO 970 frequency dou bler that installs inside the laser head The table top controller can be placed near the head in a convenient location typically under the BeamLok PRO series Nd YAG pump laser controller The Introduction chapter contains a brief description of the MOPO HF system and the digital controller Following that section is an important chapter on safety The MOPO HF is a Class IV laser product and as such emits laser radiation which can per manently damage eyes and skin This section contains information about these hazards and offers suggestions on how to safeguard against them To minimize the risk of injury or expensive repairs be sure to read this chap ter then carefully follow the instructions listed there Laser Description contains a short section on MOPO theory regarding the BBO crystal and frequency doubling using the Model FDO 970 and is fo
78. RATE button is pressed once from the Operatel menu OPERATE 900 0000 MONITOR 1220 814nm SIGNAL NORM nm It displays e Signal large and idler small output wavelength if SIGNAL is selected in the Operate2 menu or e Idler large and signal small output wavelength if IDLER is selected in the Operate2 menu or e MOPO HF FDO large doubled output wavelength and MOPO HF source wavelength small if FDO was selected in the Operate2 menu Refer to your FDO user s manual for more information The function buttons allow you to set e the display and scan source The following is displayed when set to Operation Setting Large Letters Small Letters SIGNAL Signal Idler IDLER Idler Signal FDO FDO Signal e the display mode to NORM 6 digits or MICRO 7 digits e the displayed wavelength units either nm or cm e the master oscillator display gain 1 2 4 8 16x e the power oscillator display gain 1 2 4 8 16x The Servicel Menu page 6 14 is displayed when the OPERATE button is pressed twice from the Operatel menu SERVICE OPMOD IDL SGWVL 500 0000 MOPWR 0 POPWR 15 SETUP1 MOSET 16547 MOVAL 16547 MONITOR1 POSET 15482 POVAL 17399 Pee See qo Ime It displays the MOPO HF mode setting e output wavelength master oscillator and power oscillator output power e the relative set point and actual values for the MO crystal e the relative set point and actual values for the PO cr
79. STRS Shots GOSUB WriteMopo Cmd source scans STRS scans GOSUB WriteMopo B 21 Quanta Ray MOPO HF Optical Parametric Oscillator INCREMENTAL SCAN SETUP VERIFICATION GOSUB ReadSetup faultflag 0 IF Responsel lt gt ScanBegin THEN faultflag IF Response2 lt gt ScanEnd THEN faultflag 1 IF Response6 lt gt Increment THEN faultflag IF Response4 lt gt Shots THEN faultflag IF Response5 lt gt scans THEN faultflag PRINT PRINT Incremental Scan Setup multiloop of multiloopmax PRINT TotalLoops TotalLoops PRINDI CWBee Ee 4 PRINT Parameter Sent Received PRINT MG ajaa aan ajaa AS d PRINT Begin ScanBegin Responsel PRINT End ScanEnd Response2 PRINT Increment Increment Response6 PRINT Shots Shots Response4 PRINT Scans scans Responsed PRINT IF faultflag 1 THEN PRINT Incremental Scan Setup ERROR PRINT Program Terminated END END IF Cmd scan GOSUB WriteMopo PRINT Incremental scan rumning PRINT types Incr GOSUB WaitForScan B 22 The RS 232 IEEE 488 Interface PRINT Saving parameter setup TotalLoops total loops PRINT Cmd save 3 Save curr
80. States Code of Fed eral Regulations chapter 1 subchapter J parts 1040 10 and 1040 11 as applicable To maintain compliance with these regulations once a year or whenever the product has been subjected to adverse environmental condi tions e g fire flood mechanical shock spilled solvent etc check to see that all features of the product identified below function properly Also make sure that all warning labels remain firmly attached refer to the CE CDRH drawing later in this chapter 1 Verify removing the remote interlock plug on the pump laser prevents laser operation 2 Verify the laser system will only operate when the pump laser s inter lock key switch is in the ON position and that the key can only be removed when the switch is in the OFF position 3 Verify the emission indicator on the pump laser works properly that is it emits a visible signal whenever the laser is on 4 Verify that the time delay between turn on of the pump laser emission indicator and that starting of that laser gives you enough warning to allow action to avoid exposure to laser radiation 5 Verify removing the cover of the pump laser shuts off the laser Any electronic product radiation except laser radiation emitted by a laser product as a result of or necessary for the operation of a laser incorporated into that product Quanta Ray MOPO HF Optical Parametric Oscillator Safety Interlocks Danger Laser Radiation Battery D
81. TM without clipping the UVBS 10 Change to Q SWITCH OFF mode 11 Remove the two base plate shipping bolts on the MOPO HF This allows the base plate to expand and contract freely with changes in temperature Otherwise the MOPO HF can misalign with tempera ture cycling 12 Clamp the MOPO HF to the table If the base plate is not secured to the table removing or replacing the cover or the MOPO HF FDO might misalign it Caution n Carefully lift each corner of the MOPO HF base plate Because the unit is secured to the top of the table it should not move If a particular cor ner moves perform a counterclockwise adjustment of the foot until the corner is secure Quanta Ray MOPO HF Optical Parametric Oscillator Note Verifying BeamLok Beam pointing Sensor Alignment 13 14 15 Access the BeamLok Monitor menu refer to the PRO Series User s Manual and verify BeamLok is off This minimizes adjustment time when BeamLok is again engaged at the conclusion of the alignment procedure Change to Q SWITCH mode Optimize the HG crystal settings to ensure the system is optimized for power This step is very important for proper BeamLok operation Be sure to leave BeamLok off 16 17 Verify the horizontal and vertical bars on the BeamLok Monitor menu are at the center of the cross hairs If the bars are not at the center a Change to LONG PULSE mode b Carefully remove the PRO Series
82. TO START move RECALL SAVE SCAN 0 0 MONITOR Begin predetermined scan routine Figure 6 10 Initiating a Scan 1 Set the system set to TRACK mode TRACK is selected via the Monitorl menu When TRACK mode is selected an L is displayed in the lower right portion of the Operate menu Select SIGNAL IDLER or FDO from the Operate2 menu for the desired output wavelengths From the Setup menu set the scan BEGIN and END wavelengths a Press the BEGIN button then use the procedure outlined under Setting Numeric Values on page 6 7 to set the BEGIN wavelength value b Press the END button then do the same to enter the end wavelength value Set the number of scans desired Press the SCANS button then use the same procedure to set the number of scans desired If an incremental scan is desired set the SHOTS value to the number of shots required per dwell If a continuous scan is desired set the SHOTS value to 0 and set the scan rate the number under CONT in nm s If an incremental scan was selected in the previous step set INCR to the number of nanometers desired between dwells Press the OPERATE button to return to the Operatel menu Press the START SCAN button to begin the scan process When the scan process begins the Operate menu changes to indicate the progress of the scan re
83. The L denotes the selected device is properly set to track mode when absent it is set to table mode The number in the upper right hand corner is the current wave length for which a value is being computed The wavelength range depends on the mode selected SIGNAL IDLER or FDO from the Operate2 menu OPERATE1 M OSC P OSC 500 000 PWR 12374 PWR 12374 SETURE SET 12097 I SET 12097 L MONITOR1 POS 12073 MO_CRYS POS 12073 L Your choices in the next steps depend on the table writing method chosen e g Y_SHIFT has only 1 value point LIN_INT has 2 LAGRANG has 7 and LSQ_MRG has 10 MO AUTO automatically determines a value for every 1 nm between the chosen beginning and ending scan points MANUAL does not let you save values at all but is used to perform what if trials Operation If not already at the begin scan point the system will move there first Once at the begin scan point note the wavelength shown on the menu screen use the up down buttons to modify the position of the selected crystal except for OPO_AUTO which does this automatically As the crystal moves the bar graph showing the detected beam power moves upward as the system approaches the optimal position for highest power and down ward when moving away from the ideal crystal position 4 Optimize the crystal position at each value point a Use the up down buttons to optimize the crystal position then press the CONT button to write the
84. The MONITOR label changes to REMOTE and the SELECT IEEE 488 and BAUD functions are displayed in the display boxes F SELECT allows the user to set the control interface to IEEE 488 RS 232 or LOCAL F IEEE 488 allows the bus address to be set F BAUD allows the serial baud rate to be set 2 Set the address for the IEEE 488 interface from 0 to 31 default is 15 a Press F to place the cursor under the digit to be changed b Use the up down keys to toggle to the digit desired c Move to the second digit if necessary and repeat Steps a and b d When the address is selected press F until it beeps to activate the address 3 Set the serial baud rate to 300 1200 or 2400 default is 2400 a Press F to select the baud rate b Use the up down keys to toggle to the rate desired c Press F until it beeps to activate the baud rate 4 Select the active interface a Press F momentarily b Use the up down keys to toggle to the interface desired c Press F until it beeps to activate the selected interface The MOPO HF controller should now be set to either the RS 232 or IEEE 488 remote control modes and command and query messages can now be sent to it from your computer The selected interface will remain active until changed again by you 5 Press F5 LOCAL to return control to the front panel Saving Setup Parameters The RS 232 and IEEE 488 setup parameters will not be saved via remote command Only GOTO and
85. VDC gt Figure 5 20 Orientation of the BBO Crystal 10 a Loosen the compensator holder Rotate the compensator so that the retroreflection closest to the optic is on the left side of VDC c Verify the compensator is centered in the beam Make adjustments if necessary d Tighten the compensator holder If necessary re adjust the OC so the primary retroreflection is directed back onto the PH pinhole aperture Install the PO BBHR in its standard location on the base plate The nominal separation between the OC and PO BBHR is 13 cm Adjust the PO BBHR so the retroreflections are directed onto the PH pinhole Method B PO has not been previously aligned Remove all optics out of the beam path of the PO This includes the PO BBHR PO TM PO TM BBO crystal OC compensator and S TP Place an aperture assembly on the dowel pins at PH and secure it to the base plate with a 10 32 screw The aperture will be used as an alignment reference Establish alignment of the reference beam a Place alignment mirror R TM approximately 1 foot 30 cm in front of PHg The space between the MOPO HF and the routing mirror leaves room for the placement of a power meter b Place an aperture assembly on the dowel pins at PH Adjust R TM to center the reference beam on PH then adjust R TM to center the reference beam on PH d Iterate the last step until the beam is centered through the two pin holes Place a
86. Writing Procedure on page 6 31 Once selected the button display changes to ABORT to allow you to abort this process and keep the present value 6 19 Quanta Ray MOPO HF Optical Parametric Oscillator 6 20 F SET PEAK allows you to set a peak value for the PO PD refer to the Threshold Table Writing Procedure on page 6 31 Once selected the screen changes to show the master and power oscillator output as shown below F selects the master oscillator crystal and F selects the power oscil lator crystal for adjustment F moves the peak setting to the next 10 nm F CONT appears only after changing a table value and it allows you to continue on to the next point Once all the values are entered for the selected method the SAVE button appears in this location so that you save the val ues you just entered Neither the CONT nor SAVE buttons appear when the MANUAL or MO_AUTO or OPO_AUTO methods are selected all adjustments are only temporary when the MANUAL method is selected and the move ment between points the calibration and the final save are all automatic when the MO_AUTO or OPO_AUTO method is selected F4 SAVE appears once all the values are entered for the selected table writing method so that you can save these values in the user table Neither the CONT nor SAVE buttons appear when the MANUAL or MO_AUTO or OPO_AUTO methods are selected all adjustments are only temporary when the MANUAL method is selected
87. a tion settings and system performance refer to The Display below The Setup1 Menu Operation This menu allow you to identify your software revision number which is required when determining whether or not to update the firmware and whenever you talk to your Spectra Physics service representative The Display Displayed is the selected operating mode OPMOD the output wavelength SGWVL the master and power oscillator power MOPWR and POPWR and the setpoint and actual count value for both the master and power oscil lators MOSET MOVAL and POSET MPVAL When the system is operating properly the actual count should be fairly close to the setpoint value The Function Keys F INFO displays the software revision number F FRMWRE INSTALL walks you through several steps that allow you to save your current table values while you update the system operating sys tem Use this function only after you have received a new PCMCIA card with the new operating system on it F4 N A F4 N A F4 RESET WL performs a self diagnostic reference check of the wave length grating calibration to look for gross calibration errors Press this whenever you suspect a wavelength error an error message is usually dis played on the screen Select SETUP1 menu Current Signal wavelength Current Idler wavelength N PERATE A SETUP 500 000 650 000
88. a exposicion straling geemiteerd et invisible est emis setzen vermijd blootstellilng par cette ouverture Non Attention Rayonne Vorsicht beim Offnen Peligro Cuando se Gevaar zichtbare en Inter ment Laser Visible et Austritt von sichtbare abre existe Radiacion niet zichtbare laser locked Invisible en Cas und unsichtbare Laser Visible e Invisi straling wanneer 3 D Ouverture Exposi Laserstrahlung ble Evite que los ojos geoend vermijd tion Engereuse de Bestrahlung von y la piel queden blootsteling aan huid L Oeil ou de la Peau Auge oder Haut expuestos tanto a la of oog aan disecte au Rayonnement durch direkte oder radacion directa straling of weer Direct ou Diffus Streustrahlung ver como a la dispersa kaatsingen meiden CE Non Rayonnement Laser Beim Offnen Austritt Cuando se abre Zichtbare en niet Inter Visible et Invisible en von sichtbare und existe Radiacion zichtbare laser stral locked Cas D Ouverture unsichtbare Laser Laser Visible e Invisi ing wanneer geoend Label Exposition strahlung Bestrahl ble Evite que los ojos vermijd blootsteling 4 Engereuse de L Oeil ung von Auge oder y la piel queden aan huid of oog aan ou de la Peau au Haut durch direkte expuestos tanto a la disecte straling of Rayonnement Direct oder Streustrahlung radaci n directa weerkaatsingen ou Diffus vermeiden como a la dispersa CDRH Attention Vorsicht Austritt von Peligro al abrir y reti Gevarr zichtbare en Logo Rayonnemen
89. ag ga Bk ah agan ara ga a BI E a RN Ta hm e KA gah ee 6 21 The Monitor MENU kaa 00 004 nm ese s ank Kg Ace E eg bee rave Saas 6 23 Switching Between MOPO and FDO Operation_ lt cece 6 24 Switching from MOPO to FDO Operation tees 6 24 Switching from FDO to MOPO Operation 0 ccc ete 6 24 RUNNING a Scan e Ro RE ae oe cu V Eat x ae A NA ee 6 25 Operating at Fixed Wavelengths a e hne 6 26 MOPO Table Writing Procedures aa ttt 6 27 General Table Writing Procedure 0 ccc ne 6 28 Reloading the Theoretical Table Values_ cece eee 6 29 Re establishing User Defined Tables 0 cece teeta 6 30 Lagrangian Table Writing Procedure a eee 6 31 Threshold Table Writing Procedure ec rh 6 31 Automatic Table Writing Procedure 0 00 tees 6 33 Chapter 7 Maintenance 0c eee eee eee eee nn nnn 7 1 Preventative Maintenance a ak ee eee rn 7 1 Cleaning of Laser Optics herida kat heb eee A Galea Ghee eae das de ean a 7 1 Cleaning Optical Components aa aa aaa tenes 7 2 Chapter 8 Service and Repair aaa aaa a aaa aaa eee 8 1 Troubleshooting Guide a rmm 8 1 Par ao doe ee cs aah oA dyes jan Ped ne nd A Bien A 8 2 Part 2 Aaa CL Ate us bah da naba Sc gagana a Ab e UL Eee tud a a ND aana o tes 8 3 Replacement Parts deer Ee ee Wa edo ee BN 8 5 Chapter 9 Customer Service aaa eee eee 9 1
90. am The Fresnel reflections may be viewed with a business card If clipping is present do the following to correct it a Turn to LONG PULSE mode b Adjust the position of BS c Turn to Q SWITCH mode d Evaluate beam clipping If clipping is still present repeat the above steps until it is elimi nated Optimize the signal level on PO PD a Access the monitor menu on the MOPO HF controller b Note the signal levels on the PO monitor c Maximize the signal level on the PO monitor by adjusting its posi tion so that the Fresnel reflections from BS are centered on the detector d Adjust the gain potentiometer on the monitor if signal levels are too low or high Optimal alignment of the seed beam to the PO is now achieved Engage BeamLok 1 2 3 Access the BeamLok menu on the PRO Series controller Verify BeamLok is off If the vertical and horizontal bars in the display menu are not at the center of the cross hairs perform the following a Turn off the laser b Carefully remove the PRO Series laser cover c Turn on the laser d Set the PRO Series laser to Q Switch mode and verify the UV energy is at maximum e Use a 3 64 in hex wrench to adjust the pointing sensor so the hori zontal and vertical boxes are overlapped Use gain level 4 for optimal adjustment sensitivity Turn off the laser Place the cover back on the pump laser Set the PRO Series laser to Q Switch mode Engage BeamLok Bw
91. and thus only operates when the pump wave is present 355 nm 400 nm 710 nm 2000 nm Input Pulse Output Wavelength YAG MOPO Figure 3 3 Theoretical signal and idler Output wavelengths for 355 nm Pump In the MOPO HF system the pump wavelength Ap is always 355 nm In theory however an infinite number of signal and idler wavelengths exist to satisfy equation 1 The angular dependence of the birefringence in aniso tropic crystals such as BBO results in a variation of refractive index as the crystal is rotated By fixing the pump wavelength and beam path any vari ation in signal and idler index of refraction caused by a rotation in the crys tal will vary the wavelength resonated within the cavity thus allowing tuning to be accomplished For further information on OPO theory refer to Tunable Optical Parametric Oscillators by Steven E Harris Proceedings of the IEEE Volume 57 No 12 December 1969 p 2096 2113 BBO Enables OPO Commercialization 3 2 The commercialization of OPO technology has taken more than 25 years due to the lack of suitable commercially available nonlinear materials In order for a material to be suitable for OPO use the crystal must possess five critical properties simultaneously e Phase matching conditions for pump signal and idler wavelengths over the tuning range of interest MOPO Operation Master Oscillator Description e High damage threshold to sustain the intense pump fluence requir
92. anel The digital controller contains the CPU that controls the various circuits required to select wavelengths Control and monitoring capability is pro vided via a front panel LCD display and 10 buttons A structured menu sys tem provides a logical means to control and monitor the system Connectors on the back panel link the controller to the MOPO HF head Chapter 6 contains a complete description of the controller its menus and its operation The digital controller is operated using an LCD display and ten buttons on the front panel Figure 4 3 Each press of a button either brings up a differ ent menu or modifies some variable Menu Buttons Status Display Panel Up Down Buttons OPERATE A SETUP Moro G Spectra Physics Figure 4 3 The Digital Controller Front Panel Soft Key Function Buttons LCD display provides a visual means for accessing the system s menu driven program Depending on the menu displayed and the function key pressed it shows the status of a variety of system parameters and allows you to follow the operation of the system as you input commands and 4 9 Quanta Ray MOPO HF Optical Parametric Oscillator Rear Panel 4 10 change parameters Help menus and instructions are shown from time to time to provide assistance To show which function or item is selected prior to making it activ
93. are centered on the detector If necessary adjust the pointing of the BS mount to max imize the signal d Adjust the gain potentiometer on the monitor if signal levels are too low or high Optimizing Seed Beam Alignment The following optimizes the alignment of the seed beam to the PO resona tor Part I describes the alignment of the seed telescope In Part II the PO is converted into a low energy OPA optical parametric amplifier Adjust ments are made to ensure collinear alignment of the seed beam to the PO pump beam In Part III the seed beam is blocked and the PO is converted back into an oscillator Collinear alignment of the unseeded PO is verified Part I Seed Telescope Alignment 5 40 Method A PO has been previously aligned 1 2 10 Change to LONG PULSE mode Place the top half of the seed telescope assembly back onto its base assembly Use a 16 in hex wrench to remove the 1 in optic barrel that contains the positive lens Change to Q SWITCH mode Oscillation in the MO should resume The seed beam should be roughly centered on the negative lens If this is the case proceed to Step 6 If the beam is clipping the lens mount loosen the seed telescope base plate screws and slide the telescope base laterally to center the seed beam horizontally in the negative lens coarse x axis adjustment Next tighten the telescope base plate screws Using a 16 in hex wrench adjust the x and y position of the
94. as been a loss of user table data data corruption has occurred a grating re calibration has been completed or there has been a movement or realignment of either or both of the crystals i e when the current values no longer match your system and you cannot get your system running Because only the user table can be active its values must be replaced with those from the theo retical table in order to use the latter The General Table Writing Procedure below describes a typical table writing routine and explains what you can expect from each table writing method The next two sections Reloading Default Table Values and Re establishing User Defined Tables are special sections designed to get you out of trouble if your user table no longer matches your system an optic was moved or realigned These two sections plus the sections that follow them the Lagrangian Table Writing Procedure and Automatic Table writing Procedure get you back up and running The latter two sections especially the Automatic Table writing Procedure are the only routines normally used for day to day operation The Reloading Default Table Values procedure assumes the worst that your table values are corrupted or that your system was so altered that it no longer matches your table values This procedure will re load the theoreti cal values into the user table and give you a starting point Please note all your previous
95. as listed in the official Journal of the European Communities It also meets the intent of Directive 73 23 EEC for Low Voltage Class A com pliance was demonstrated for EN 61010 1 1993 Safety Requirements for Electrical Equipment for Measurement Control and Laboratory use and EN 60825 1 1992 Radiation Safety for Laser Products Refer to the CE Declaration of Conformity statements in Chapter 2 Finally if you encounter any difficulty with the content or style of this manual please let us know The last page is a form to aid in bringing such problems to our attention Every effort has been made to ensure that the information in this manual is accurate All information in this document is subject to change without notice Spectra Physics makes no representation or warranty either express or implied with respect to this document In no event will Spectra Physics be liable for any direct indirect special incidental or consequential dam ages resulting from any defects in this documentation Finally if you encounter any difficulty with the content or style of this manual please let us know The last page is a form to aid in bringing such problems to our attention CE Environmental Specifications CE Electrical Equipment Requirements For information regarding the equipment needed to provide the electrical service listed under Service Requirements at the end of Chapter 3 please refer to specification EN 309
96. assing through the polarizer and crystal is dis placed above the line on the exposed piece of paper then the optic axis orientation may be visualized as beginning on the bottom corner of the viewer s side of the crystal and extending to the opposite corner CASE Il If the line passing through the polarizer and crystal is dis placed below the line on the exposed piece of paper then the optic axis orientation may be visualized as beginning on the top corner of the viewer s side of the crystal and extending to the opposite corner 8 Using a pencil draw a diagonal across the both sides of the crystal to indicate the optic axis orientation as shown in Figure A 3 9 Now use a pencil to mark the master oscillator crystal with one dot in the upper right hand corner Mark the power oscillator crystal with two dots as shown in Figure A 3 A clockwise rotation of the master oscillator crystal results in a counter clockwise rotation of the power oscillator crystal Such a rotation of the crystal shaft will tune the MOPO HF to the red end of the spec trum Master Oscillator Power Oscillator a Viewer RN Side View Of Side View Of Master Oscillator Power Oscillator Crystal Crystal Figure A 3 Observing the master and power oscillator crystals Installing the BBO Crystal A Quick Verification of the C axis Direction As described in Chapter 3 light that enters a birefringent crystal will in general
97. at 440 and or 690 nm use the following Lagrangian curve fitting routine to refine the tables 1 From the Setup menu verify that 460 nm and 660 nm are entered for the BEGIN and END wavelength scan values From the Setup menu use the Setting Numeric Values procedure on page 6 7 to set the BEGIN and END wavelength values 2 Select the MO crystal for optimization a From the Setup2 menu press the DEVICE button then use the up down buttons to scroll to MO_CRYS b Press and hold the DEVICE button until it beeps to activate your selection 3 Select the Lagrangian table writing method and move the system to the begin wavelength a Press the METHOD button and use the up down buttons to scroll to LGRNG b Press the METHOD button until it beeps to to activate your selection and to move the system to the begin wavelength 4 While watching the bar graph on the monitor use the up down buttons to maximize the output level for that value point 5 Press the CONT button to proceed to the next wavelength value Repeat the previous two steps to optimize each of the seven points in the scan range After the final point has been written press the CONT button again Press the SAVE button until it beeps Make sure you perform this step to save the table values you just entered 9 Repeat this procedure for the PO crystal starting at Step 2 This completes the Lagrangian table writing procedure Now perform th
98. atterie nur durch Reemplazar la bat Vervang batteryen Label le m me mod le ou gleichen oder baugle er a con el mismo door de zelfde of 12 un mod le quiva lent Se d barasser des piles usag es conform ment au recommandations du fabricant ichen Typ gemaB Herstellerangaben ersetzen Ver brauchyte Batterien ordnungsgemaB entsorgen tipo o equivalente recomendado por el fabricante Peligro Deshacerse de las baterias usadas de acuerdo con las instrucciones del fab ricante door de fabrikant geadviseerde equiva lente typen Voer de gebruikte battereien af volgens de instruc ties van de fabrikant 2 8 Laser Safety CE Declaration of Conformity We Spectra Physics Inc Scientific and Industrial Systems 1330 Terra Bella Avenue P O Box 7013 Mountain View CA 94039 7013 United States of America declare under sole responsibility that the Quanta Ray MOPO HF series Pulsed Optical Parametric Oscillators with digital controller manufactured after December 31 1995 meets the intent of Directive 89 336 EEC for Electromagnetic Compatibility Compliance was demonstrated Class A to the following specifications as listed in the official Journal of the European Communities EN 50081 2 1993 Emissions EN 55011 Class A Radiated EN 55011 Class A Conducted EN 50082 1 1992 Immunity IEC 801 2 Electrostatic Discharge IEC 801 3 RF Radiated IEC 801 4 Fast Transients I the undersigned
99. avelength scan range of 450 to 690 nm From the Setup menu use the method described under Setting Numeric Values on page 6 7 to enter the begin and end wavelength scan values F and Fa 9 Run the automatic table writing routine refer to the next section Note if the table writing procedure fails do the following a Write a Lagrangian table refer to the Lagrangian Table Writing Procedure on page 6 31 b Write a threshold table refer to the Threshold Table Writing Pro cedure on page 6 31 c Rerun the automatic table writing routine see below Automatic Table Writing Procedure The automatic procedure is designed to minimize the amount of time a user 1s required to spend writing tables It writes the master and power oscillator tables over an arbitrary scan range To be successful the current table must be close enough to optimal values in order for the search routines to find the appropriate peak signals Use this procedure whenever you need to update the MO and PO tables over a short scan range because they have either been realigned or one or both of the tables has drifted slightly 6 33 Quanta Ray MOPO HF Optical Parametric Oscillator 6 34 To perform the OPO_AUTO automatic table writing process which includes both the MO and PO tables Verify the system is set to track mode a If necessary from the Monitorl menu press the MOPO button then use the up down buttons to scroll to
100. away from the optic axis while the o ray propagates through the crystal undeviated from the initial beam path Optic Axis A oTayv Horizontal lt e elek eleke d Vertical lt p e ray a Type BBO Crystal Figure 5 5 Unpolarized light from a HeNe laser shown entering a birefringent crystal such as BBO The reference beam used to align the MO and PO cavities should be hori zontally polarized see Figure 5 6 This is necessary since the resonated signal wave generated in a type I BBO crystal has ordinary horizontal polarization Appropriate orientation of the sheet polarizer in this case will eliminate the lower beam at the backside of the crystal 3 Place a sheet polarizer in the output beam of the reference laser and orient it to obtain a horizontally polarized beam 4 Set up two reference beam alignment mirrors placing the first align ment mirror R TM in front of the reference laser and the other R TM in front of PH Figure 5 4 Installation and Alignment Transmission Axis Oriented to pass horizontally ALL AM polarized light Optic Axis N 4 Horizontal PULSU A A dele Unpolarized o ray N HeNe Laser N IA Type BBO Crystal Sheet Polarizer Figure 5 6 Horizontally polarized light passing through a birefringent crystal such as BBO 5 Establish alignment of HeNe beam to reference pinholes PH 4 and PH a Adjust R
101. back of the detector If necessary remove an ND filter from the filter stack Verify the pump power is in the desired range refer to Chapter 5 Installation and Alignment Check for damage optics or crystal and replace as needed Verify the master oscillator alignment with a HeNe reference beam refer to Chapter 5 Installation and Alignment Verify the pump beam reference beam overlap Replace the motor mike Tilt the face of the crystal in the horizontal plane as described in Appendix A Adjust the PO crystal angle to optimize the frequency overlap refer to Chapter 5 Installation and Alignment Adjust the PO BBHR position refer to Chapter 5 Installation and Alignment Service and Repair Replacement Parts The following list of parts can be purchased and installed by the user They are offered here in the event an item becomes damaged or lost or when an additional item is required that was not purchased with the system Table 8 1 Replacement Parts Description Part Number Window 1 in 0002 0061 Window HA30 IR Cutoff 1 in 0005 0041 1 BBO Crystal AR Coated PO 0447 9961 Compensator 0448 3690 Filter RG695 Long Wave Pass 0448 8330 355 nm Dichroic 1 5 in 0448 8440 355 nm Dichroic 1 in 0448 8450 UV reflector 0 355 nm 0448 8460 Visible Dichroic 400 700 nm 0448 8470 High Reflector 400 700 nm 0448 8480 Output Coupler 0448 8490 Beam Splitter 355nm 1 0448 8500 Lens
102. be modified a little For example if a vertically polarized HeNe beam is used the beam will walk onto a different portion of the high reflector than does the horizontally polarized beam Because the optic is curved this results in an angular offset in the retroreflected beam As a result a slight angular error in the overlap procedure may occur if a vertically polarized reference beam is used To avoid this error we will 5 30 Note Installation and Alignment overlap the pump with a horizontally polarized HeNe beam Because the HeNe beam passes through the crystal twice it will follow the same path the pump does on the output side of the BBO crystal This enables the polarization of the pump and reference beams to be orthogonal If the MOPO HF has not been previously aligned establish the refer ence beam according to Method A below Otherwise use Method B Method A MOPO HF has not been previously aligned 1 p Change to LONG PULSE mode Determine the combination of positive and negative lenses required for the telescope in the PO leg Refer to Appendix E Determination of Telescope Lenses for Power Oscillator Obtain appropriate positive and negative lenses Refer to the part num bers Appendix E Remove the PO PL mount Leave PO NL in its designated position on the MOPO HF base plate Place the positive lens in the PO PL mount Set the mount safely aside in an unoccupied hole in the MOPO HF base plate
103. below eye level e Provide enclosures for beam paths whenever possible e Maintain a high ambient light level in the laser operation area so the eye s pupil remains constricted reducing the possibility of damage e Set up shields to prevent any unnecessary specular reflections e Post prominent warning signs near the laser operating area Figure 2 1 e Set up an energy absorbing beam trap to capture the laser beam and prevent accidental exposure to unnecessary reflections or scattering Figure 2 2 INVISIBLE AND OR VISIBLE VISIBLE AND OR INVISIBLE LASER RADIATION LASER RADIATION AVOID EYE OR SKIN EXPOSURE TO AVOID EYE OR SKIN ec peat TO DIRECT OR DIRECT OR SCATTERED RADIATION CLASS 4 LASER PRODUCT POWER WAVELENGTH S AND POWER WAVELENGTH S AND PULSE WIDTH DEPEND ON PUMP OPTIONS AND LASER PULSE WIDTH DEPEND ON PUMP CONFIGURATION ce OPTIONS AND LASER CONFIGURATION MANUAL CLASS IV LASER PRODUCT SEE MANUAL 0451 8080 Figure 2 1 These standard safety warning labels would be appropri ate for use as entry warning signs EN60825 1 ANSI 4 3 10 1 Figure 2 2 Optical Beam Dump BD 5 Use of controls or adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure Operating this laser without due regard for these precautions or in a manner that does not comply with recommended procedures may be dangerous At all times during installation
104. bit any beam pointing changes Automated Control Electronics The MOPO HF series makes use of the latest generation of microproces sor based control electronics to provide the ultimate in ease of use and reli ability The front panel of the controller has a large easy to read backlit LCD display and push button controls provide simple access to menus that allow you to set all the necessary operating parameters Options include continuous or incremental scans scan speed scan increment delay times number of scans and home position Optional RS 232 and IEEE 488 inter faces and even a fax modem allow easy connection to existing laboratory control and data acquisition equipment The controller contains a UL compatible switching power supply a micro processor based controller pc board and a drive pc board for crystal rota tion the BBO crystal is tuned by rotating the crystal to a known angle for each wavelength Tuning Curves Energy mJ 80 Pump Laser 60 Idler PRO 250 10 since PRO 230 10 40 20 400 450 500 550 600 650 700 900 1100 1300 1500 1700 1900 Wavelength nm Figure 3 10 MOPO HF Turning Curves Quanta Ray MOPO HF Optical Parametric Oscillator MOPO HF Specifications 3 10 Table 3 1 MOPO HF Output Characteristics Polarization Horizontal gt 97 Beam diameter typical 5 mm Beam shape typical Round 20 Beam divergence lt 1 mrad Pointing stability lt 200 prad Pulse width typi
105. bstructed into the PO b Place PH back onto the base plate c Remove the hex wrench from the OC mount Verify the retroreflections from the OC and PO BBHR optics are directed onto the center of PHg If they are not make the necessary adjustments to center them on the pinhole Be sure to place a card in front of PO BBHR while checking the OC retroreflections e Using a business card verify the pump and HeNe beams are still overlapped Make any necessary adjustments to the positive lens for course alignment and the negative lens for fine alignment 24 Remove PH 25 Remove the pick off prism Place PO TM back onto the base plate 26 Adjust the PH location to center the pinhole on the LONG PULSE beam 27 Direct the beam into the mini beam dump MBD Attaining Oscillation in the Power Oscillator Verify the pump laser is in LONG PULSE mode 2 Prevent oscillation in the MO during subsequent steps in the procedure by placing a business card over MO BBHR Figure 5 15 3 Using the MOPO HF controller go to 500 nm 5 36 Note Danger W Warning W Note Installation and Alignment a Access the OPERATE screen and enter 500 nm in the GOTO menu b Press the GOTO button down and hold it until a beep is heard Verify a power meter head is in the output signal beam path This will be used to measure the signal output power as well as to judge overall stability and seeding optimization Place a beam dump a
106. cal 2 ns less than pump Resettability lt 1 x linewidth Electronic readout accuracy typical lt 10 x linewidth Long term stability 1 x linewidth C hr Pulse to pulse stability 10 Timing jitter lt 2 ns Linewidth 0 075 cm Table 3 2 Output Energy vs Pump Source Pump Laser Output Energy PRO 290 10 p PRO 290 30 a PRO 270 10 a PRO 270 30 ae PRO 250 10 60 PRO 250 30 sE PRO 230 10 40 Table 3 3 Tuning Characteristics Signal tuning range typical 440 to 690 nm Idler tuning range typical 735 to 1800 nm 1 All specifications subject to change without notice The parameters marked typical are not specifications They are indications of typical performance and will vary with each unit we manufacture Unless stated all specifications are at 500 nm Beam diameter is measured in the Signal wavelength range at the e vary depending on the pump source energy level Measured at 1 m from the output in the Signal wavelength range Full angle measured at the e point 3 Over an 8 hour period with temperature variations of lt 3 C 6 Pulse to pulse stability for gt 99 of pulses measured over 1 hour 7 rms jitter from the O switched sync pulse in the PRO series pump Nd YAG laser using an injections seeder 8 Measured at 500 nm only Typically 0 2 cm across the tuning range Specifications at 500 nm for the Signal wavelength only See the tuning curves for typi cal output at other wav
107. call or letter to our service department but that you feel should be remedied We are always interested in improving our products and manuals and we appreciate all suggestions Thank you From Name Company or Institution Department Address Instrument Model Number Serial Number Problem Suggested Solution s Mail To FAX to Spectra Physics Inc Attention ISL Quality Manager ISL Quality Manager 650 961 7101 1330 Terra Bella Avenue M S 15 50 Post Office Box 7013 Mountain View CA 94039 7013 U S A E mail salesO splasers com www spectra physics com
108. ch is depressed B 27 Quanta Ray MOPO HF Optical Parametric Oscillator B 28 Appendix C Replacing the PCMCIA Card Battery The 512 kB PCMCIA memory card found in the MOPO HF controller uses a small 3 V disk battery to maintain the data stored in it The expected lifetime of the battery is approximately 2 3 years so it is prudent to change the battery every 2 years regardless of use If the battery dies the data is lost and a full system recalibration is required The different brands of PCMCIA cards used in these systems are described below Following this description is a procedure for changing the battery without losing the data Determine which card you have then read the pro cedure completely through making sure you understand it before you begin Card Insertion E SR T gt Write Protect L A Write Protect ey Write Protect wee wa A 4 Po gt Screw Release Screw Release Latch Release Battery type BR2325 Battery type BR2325 Battery type CR2025 Positive side up Positive side up Positive side up Figure C 1 Three examples of PCMCIA cards Card Description Replacement Battery List The following are the five types of 512 kB SRAM cards currently used 3 volt batteries are used in all units but size and part numbers vary Mitsubishi MF3513 LCDATO1 Silver with blue patch and white edge trim Screw retains battery Battery BR2325 C 1 Quanta Ray MOPO HF Optical Parametric Oscillator Procedure Caution
109. controller The system is now ready to receive commands for operation MOPO FDO Firmware Revision In the MOPO HF ID message shown above the last piece of data specifies the revision level of the MOPO HF system firmware The ID message should indicate that the MOPO HF system firmware is Version 2 03 or a later revision The RS 232 IEEE 488 Interface Format and Syntax Rules Format Syntax Message Termination All messages sent to the MOPO HF must be transmitted in ASCII format The MOPO HF also sends back all response data in ASCII format The syntax of the messages sent must conform exactly to the syntax of the examples shown in the next section on Command and Query Messages Notice that all messages begin with a colon A colon is also required between key words of the command string Use the ASCII Line Feed character to terminate all messages that are sent to the MOPO HF The MOPO HF terminates the response messages that it sends to your computer in two ways It sends the ASCII Line Feed character at the end of all messages Also when using the GPIB interface it additionally sends the GPIB END bus message Programming Examples PRINT 1 OPEN COM1 2400 N 8 1 FOR RANDOM AS 1 The following program statements illustrate the correct format and syntax of MOPO HF command and query messages These examples are written in Microsoft QuickBasic
110. crystal surface Adjust MO TM to overlap the pump and HeNe beams If necessary block the reference beam periodically to estimate the relative positions of the two beams Locate the pump beam position on the alignment card If it is not visible on this card use a separate business card to locate it Note Note g Installation and Alignment Adjust the MO TM horizontal and vertical so the pump and HeNe beams are overlapped on the alignment card This step ensures that both beams are in the same horizontal plane i e identical dis placements from the base plate g At this point the beams will not be overlapped in front of the crystal h Adjust only the MO TM horizontal control so the pump is over lapped with the right most mark on the alignment card Again adjust MO TM to overlap the pump and HeNe beams in front of the BBO crystal Repeat Steps g i until the PRO Series pump beam is 2 cm to the right of the HeNe beam and overlap is achieved in front of the crystal As a final check of the alignment adjust the MO TM horizontally so the beams are overlapped at the card The pump beam may begin to clip the edge of the crystal but do not be concerned about this If the beams appear displaced in the vertical direction make the necessary adjustments to MO TM to overlap them Finally readjust only the MO TM horizontal control so the pump beam is overlapped with the right most mark on the alignment card
111. cy over the desired tuning range and a broadband reflective tuning mirror critically mounted on a high resolution sine bar drive to provide lin ear scanning capability In addition two high damage threshold 355 nm dichroics are inserted into the cavity to route the pump beam through the BBO gain medium then out of the resonator and into a beam dump This patented design avoids the necessity of directing the pump beam through the resonator optics which have limited damage threshold capability due to coating materials and optical design constraints The grazing incidence cavity also referred to as the Littman oscillator can provide the necessary dispersion to achieve narrow linewidth output As with other wavelength selective optics the grating adds a significant amount of loss to the cavity In a Littman cavity a larger incidence angle nearer to 90 degrees increases the wavelength selectivity but also signifi cantly increases the cavity losses Increased cavity losses in general will shrink the effective tuning range In the MOPO HF the incidence angle and grating design parameters were chosen to minimize the losses at a level where the tunability of the oscillator is not compromised yet still provide suitable wavelength selectivity to achieve the linewidth specification 0 075 cnr mean linewidth 3 3 Quanta Ray MOPO HF Optical Parametric Oscillator 3 4 When a pump pulse enters the BBO crystal in the master oscillator quan
112. d idler positions in the focus of the lens Several idler output beams may be noticed in the far field These are due to multiple Fresnel reflections from the surfaces of wedged optics in the PO The main output beam is the largest one and contains most of the energy 5 37 Quanta Ray MOPO HF Optical Parametric Oscillator 10 Use this procedure to achieve collimation of the signal output beam a Set to LONG PULSE mode b Remove R TM from signal beam output path c Place power meter or a beam dump 2 3 m from signal beam out put port d Set to Q SWITCH mode Take mode burns of the signal at the output and 2 m away Evaluate the collimation of the beam f Set to LONG PULSE mode g Adjust the position of PO BBHR in the appropriate direction see info byte below to optimize collimation of the signal and idler output beam h Set to Q SWITCH mode i Evaluate the collimation of the signal beam j Repeat the above steps until the best possible degree of collimation is achieved Note Moving the PO BBHR toward the output coupler will add more diver gence to the signal beam Moving it away from the output coupler will add more convergence character to the beam MOPO Collimation Note S Additional optimization steps will be discussed in Fine Tunning the 11 Use the power meter to determine the output pulse energy of the signal beam The signal output energy should be in the range 10 35 mJ at 49
113. dth walk out of the cavity and do not oscillate After passing through the crystal the photons encounter the broadband high reflector and are retroreflected back into the cavity in the phase matching direction The number of signal photons in the second round trip through the cavity dominates the parametric light generated by quantum noise fluctuations Thus the gain realized for the spectrally narrowed sig nal photons dominates the gain experienced by other wavelengths Further passes through the resonator continue to occur until the oscillation thresh old is reached Once this happens multiple passes through the resonator result in gain depletion of the pump pulse and useful parametric output from the MOPO HF Figure 3 5 In addition the increased number of interactions with the grating enhances the wavelength narrowing perfor mance of the resonator The pump pulse continues to be depleted until the round trip gain level drops below threshold and oscillation ceases Power Oscillator Description Undepleted ox Depleted Parametric Pump Pulse 2s Pump Pulse Output Pulse lt At 10 12ns i gt lt x At 3 4ns gt time gt time time Figure 3 5 Pump pulse depletion and resulting parametric output pulse The key feature of the power oscillator is the use of a geometrically unsta ble resonator design originally patented by Quanta Ray for use in Nd YAG lasers Previous OPO designs employed convent
114. e Do not lean on the PRO Series laser or MOPO HF FDO units during operation nor place items on them Also do not lean on the optical table The entire MOPO HF system is very sensitive to small amounts of movement in the beam Leaning on the optical table the PRO Series laser or the MOPO HF FDO will compromise system performance by inducing beam movement Do not remove the MOPO HF FDO cover during operation The cover prevents room drafts from compromising temperature sta bility and also maintains a dust free environment for stable long term operation For reasons of safety 1t keeps stray beams and reflections confined Check the optics on a regular basis for dust and damage If dust is present blow it off with air or dry nitrogen This will help prevent damage to them If damage is present replace the damaged optics as soon as possible to prevent further damage to them If damage is present turn the system off immediately to prevent damage to the BBO crystal and other optics Notify your Spectra Physics service representative of the problem Monitor the UV pump power on a daily basis Important As specified in the Daily Start Up procedure of this MOPO HF manual a combined warm up period of approximately 45 minutes is required before the UV power can be reliably read Monitor the flash lamp lifetime of the pump laser If performance is below specification and the flash lamp lifetime is greater than 30 mil
115. e Threshold Table Writing Procedure below followed by the Automatic Table writing Procedure to complete this process Threshold Table Writing Procedure In the power oscillator it is necessary for the servo system to be able to dis criminate between an increase in signal due to noise or a fortuitous bump in the tuning curve a false increase and an increase that is due to seeded operation a true increase This challenge which is caused by the system oscillating when unseeded is addressed by using a threshold table Sig nal increases that are above the threshold value are interpreted as real and the servo system is activated in order to find the peak Signal levels below the threshold value are treated as noise and the system ignores them and the servo system remains inactive For the master oscillator the threshold serves to discriminate primarily between noise and oscillation signals 6 31 Quanta Ray MOPO HF Optical Parametric Oscillator 6 32 Toward the red end of the spectrum the MO detector may register small leakage signals from the power oscillator that must also be detected and discriminated against The system calculates the threshold using the following procedure First a baseline is created by recording the signal levels of the MO and PO detec tors over the entire wavelength range provided the MO is not oscillating Second a routine is run that allows the MO and PO to oscillate and th
116. e the button or associated window is highlighted with a box To indicate which menu or function is active it is shown in reverse video To make it active the associated key must be pressed and held in until it beeps To change the data associated with a button select the button an outline box appears use the up down keys to toggle through the valid selections then either a press and hold the key until it beeps to make it active or b press and hold the SAVE button when displayed to save the data Mode buttons 3 are the three buttons to the left of the display They allow selection of the Operate Service Setup Remote and Monitor menus The first press of any button brings up the menu whose name appears next to the key Further presses of that key toggles the selection to the next menu Soft keys 5 the five buttons below the display allow you to select a variable to change implement an action change to a sub menu etc Their functions depend on a which menu is currently active and b which func tion key was previously selected if any These keys are referred to throughout this manual as function keys 1 through 5 F 5 Up down push buttons 2 to the right of the display are used to either change the numerical value inside a selected function a box appears around the selection or to scroll through various pre set selections Optional RS 232 IEEE 488 On Off Power Voltage Select Interface Connections Switch
117. e This procedure assumes the PRO Series seed beam is collinear with the fundamental beam a b g Change to Q SWITCH OFF mode Turn on the PRO Series seeder unit Use an IR card to locate the PRO Series seed beam near the funda mental output port Use s and 16 in wrenches to adjust the two legs on the output end of the PRO Series pump laser so the beam at the output port is 19 37 cm 7 63 in above the table Use the s in wrench for the adjustment nut and the 16 in wrench for the locking nut Adjust the back two feet until the beam is 7 s in above the table at a location 2 3 m from the laser Repeat this step until the beam is 7 s in above and parallel to the table surface Tighten the lock nut on each leg 4 Setthe 355 nm beam height so it too is 7 g in above and parallel to the table surface a Verify the system is still set to Q SWITCH OFF mode 5 3 Quanta Ray MOPO HF Optical Parametric Oscillator 5 4 b Verify both the 2 and 3 harmonic crystals in the harmonic gen erator HG are in the beam path The 2 harmonic crystal arm should be in the I position for type I phase matching or the IP position for type II phase matching The 3 harmonic crystal should be in the T position a Eyewear Required Laser radiation is present Be sure to wear protective eyewear at all times c Place a beam dump in front of the PRO Series seed beam so
118. e pump beam This may be done by increasing the separation of the two beams in increments of 2 mm on the alignment card see Step 12 of the Master Oscillator Overlap Procedure in Chapter 5 e Occasionally linewidth from the MO may be improved by pumping closer to threshold This may be achieved by adjusting the halfwave plate on the pump laser harmonic generator to reduce pump laser out put energies Locking Issues Appropriate locking in the PO requires that the ratio of seeded to unseeded output generally be greater than 1 2 In general the larger this ratio the bet ter the system performs This is related to the servo system s ability to dis criminate between seeded and unseeded operation As the power ratio increases the error signal discriminant increases Under these conditions the system should lock readily 6 3 Quanta Ray MOPO HF Optical Parametric Oscillator When the ratio is small the error signal decreases In this case locking becomes more difficult Threshold values are used by the system to assist in discriminating between local maxima and the absolute peak associated with a fully seeded system e Ifthe PO has difficulty locking and it has been a day or more since the system has been operated it may be necessary to refresh the threshold table This is done by rewriting the base amp peak table values i e use the Set_Base and Set_Peak algorithms e If locking the PO is difficult after a threshold table
119. e sites is included at the end of Chapter 9 Customer Service This guide is divided into two parts and each has two columns In Part 1 the left column lists the various symptoms that might occur while using the system On the right are the related possible causes of the symptom In Part 2 beginning on page 8 3 the causes are listed on the left and their correc tive actions are on the right In general find the symptom first then refer to its possible causes Some corrections will be obvious For those that are not obvious refer to causes listed in Part 2 and note the corrective action s listed there These lists are prioritized Start at the top and work down 8 1 Quanta Ray MOPO HF Optical Parametric Oscillator Part 1 Symptom Cause No output from the MOPO HF Low output power from the MOPO HF Master oscillator is not operating Output wavelength does not match display wavelength Poor mode quality Low doubling efficiency Low pump power Motor mike is at the end of its range Damaged optics Damaged crystal Low pump power Master oscillator is not seeding the power oscillator Power oscillator seeding is not optimized Master oscillator is not operating Master oscillator is not locking Pump beam pointing is unstable Optical misalignment due to temperature changes i e room tempera ture changes heat source under optical table etc Damaged optics Damaged crystal Dirty contam
120. e PRO Series laser warm up period During this warm up period the temperature in the crystals of the HG is changing Adjusting the HG during this period can result in perfor mance that changes within minutes and requires further adjustments during the warm up period Stable reliable operation of the HG can only be realized once the system has come to thermal equilibrium nominally 30 minutes e Do not run the system with damaged optics Diffraction from damage spots reduce MOPO HF and FDO conver sion efficiencies due to phase distortions as well as increase the prob ability of further damage to optics down the beam line e Do not use the VARIABLE REP RATE option with the MOPO HF FDO At different rep rates the beam will not be collimated which will result in a degradation of FDO performance as well as the possibility of damaging the optics 6 1 Quanta Ray MOPO HF Optical Parametric Oscillator Dos Warning W Caution Do not run the PRO Series laser if the Seeder is off or is performing poorly Linewidth performance will degrade and parasitic oscillations may result In addition damage to the broadband dichroics may occur Do not use the PRO Series laser SINGLE SHOT option when running the MOPO HF FDO Increased thermal lensing in the rod may result in damage due to ther mal shock to the optics In addition seeded performance of the PRO Series laser is not possible and results in poor linewidth performanc
121. e baud rate for the RS 232 serial interface as shown in the display box See BAUD Rate Selection above for infor mation on changing the baud rate F4 N A Fs N A The Monitor1 Menu Operation MO output power MO output power Select the MONITOR1 menu total and average total and average Signal wavelength gt PERATE A OPERATE1 M OSC P OSC 500000 REMOTE Ja 1428 JK 7350 SETUP ONITOR1 L L START MOPO SCAN TABLE MONITOR Y Fs Fo F3 Fu F5 E Start hold resume Select the algorythm and abort a scan for driving the MOPO Figure 6 9 Monitor1 Menu The Monitor menu is accessed by pressing the MONITOR button This menu provides a visual display of relative master and power oscillator output power and the MOPO HF tracking difference signal Although the output power displayed is a running average of the last 0 8 seconds of shots it is not an absolute indication of power but a relative reference to be used when optimizing output For increased resolution of low signals the gain of the bar graphs can be increased up to 16 times via the Operation2 menu The Display The left most bar graph expresses the master oscillat
122. e iu ag AN 3 3 Master Oscillator iii nea eee REL ER LEER Se eee ae a 3 3 Power Oscillators videa e i ete ca ee ities ia dE aus 3 5 The Seeding Process oococcooccoo lehren 3 6 Dichroic Beam Separation ke a lehren 3 7 Angle is Everything in OPOS ooocccccc hh 3 7 Automated Control Electronics 0 000 re 3 9 TUNING CUIVES nde t EPA NA aed eile ee n Rated purae erri 3 9 MOPO HF Specifications liliis rre 3 10 Service Requirements aa eher 3 11 Mechanical Specifications lille rs 3 11 Environmental Specifications liliis 3 11 Ou tline Drawings oe kes eas o M ante ene iet eco WML E a Od oe A eas 3 12 Chapter 4 Controls Indicators and Connections s 4 1 Introduction eer d uPEaUd Eel eR EROR Ear ere aim REM eta ated 4 1 MOPOc HE 4 Ces Vas a rr A a a a eun nq Se bie bo pled 4 1 External Controls cu ses be Ub AREA dt daw ER eee mle ed a ia 4 2 Internal CONOS ys sss om was A Seine ae A E Sat AE ee OE es 4 2 ItidICatoIs code iniu Rer a edhe ets tain Saale a wie PA he MES Ota iade d x 4 8 Connections 4 bowie eae e PEPIN Pe hte dee IB BE be eee Baka aga Ed ceeded 4 8 The MOPO HF Digital Controller llis Hue 4 9 Front Panel ben debate pa re epe MR DOR Da Gig dan re te ros iod us oor he d e T 4 9 Hear Panel ees b dex dre ah EY PERPE eae Matte eie e Tate tns 4 10 Chapter 5 Installation and Alignment 0000 cee eee eee 5 1
123. e nadie y E PHS A a de ma Bh dene 6 1 bg mc RM 6 1 DOS Zak Mak MU Ss Mi dis ir cb ttes t ge M ie t Aue LM dr Mo AUS 6 2 Hints Tips amp Reminders for Daily Operation ae eh 6 3 MOPO stabilllY TEN A a a ag a GA E a a a ag dag a KE kan EA 6 3 PO alignment Ree a RA KN eed aa a Di dees 6 3 MOPO linewidtli ii ix a dee dte ca soley oov e ee ti 6 3 Locking Issues ole ai Pea HE ee RR Emus rael medecin RUE UR p d A ere ien 6 3 General operation hints o o ooccoccooo hh hh 6 4 Daily Start Up Procedure ooccoocc rm mehr 6 4 Daily Shut Down Procedure aa a aaa a ea aaa aaa aa ete eee 6 5 Operating the Control Electfronics_ 000 ccc a aaa aaa mue 6 5 The SSS Select Scroll Set Procedure a aaa aaa aaa aaa aaa 6 6 Setting Numeric Values_ aaa aaa aa aa aa aaa aa aa aa aaa aa aa aaa aaa 6 7 Powering Up the System a a aaa aa aa aaa aa aa aaa aa aa aa aaa eaaa 6 7 The Menu Structure saira aaa ba KU aan GG a aa a a NA ea E a Aa SKK Ban AA NA aan GN tenes 6 7 A Brief Descriptio asas a ag ai gg KA AENG es Rove KAGAN AGE ac gee er KERN EN E KKN ad wed 6 8 The Operate Menu aa a ea ea aa aa aaa aa aaa eaaa aaa aa ea aaa 6 11 The Operate2 Menu ooo 6 13 The Servicel Menu cee ea ea ea a eaaa aa aaa eaaa aaa ea ea eaaa 6 14 The S tupi Men s eoe ii au BAG GB gang els pul doe RU Roses de e eka de Gon 6 15 The Setup2 Menu occ 6 17 The Remote Menu La ore ma aaa g
124. e noticeable on or near PH 3 Because of safety considerations the direction and degree of rotation may vary Follow one of the procedures described below Case A The crystal is marked R and there is an aluminum beam block flag attached to the upper part of the grating cage The flag should be on the side of the grating that is closest to the crystal and extend toward the tuning mirror Its purpose is to block the reflections from the crystal surface Loosen the crystal and rotate it by a small amount in the counterclockwise direction as seen from the top The two retroreflections from the crystal surface should be observed to move to the left hand side of PH 3 Settle on a crystal orientation where the retroreflection closest to the center of PH is displaced to the left hand side by about 10 mm Figure A 5 PH13 10 mm Gu 0 Pinhole Retroreflections from the crystal surfaces Figure A 5 The HeNe beam retroreflections from the crystal as seen on PH for cases A and C Case B The crystal is marked R but there is no aluminum beam block flag attached to the upper part of the grating cage Loosen the crystal and rotate it by a small amount in the clockwise direc tion as seen from the top The two retroreflections from the crystal sur face should be observed to move to the right hand side of PH 4 Settle on a Power Oscillator Installing the BBO Crystal crystal orientation where the retrorefl
125. e pump and HeNe overlap can be viewed easily on the card Place the negative lens into the PO NL mount The beam should be approximately in the center of the lens The plano flat side of the negative lens should be facing the positive lens location This is important to prevent focused back reflections from damaging PO PL Make the necessary horizontal and vertical adjustments of the PO NL lens mount position to re overlap the pump and HeNe beams on the business card at the diagnostic output port Use the following proce dure a Loosen the mount Use a 32 in hex wrench to loosen the two screws on the front side of the lens mount b Vertical adjustment Use a 16 in hex wrench to adjust the two downward facing screws on the side of the mount c Horizontal adjustment Use a 16 in hex wrench to adjust the side facing screw on the side of the mount Place the positive lens back into position in the beam line Verify the curved surface of the optic is directed away from the nega tive lens Adjust the position of the positive lens so that it is displaced from the negative lens by a distance that is approximately the difference in absolute focal lengths of the two lenses 16 17 18 19 20 Installation and Alignment For example a 1 2x telescope which consists of a 240 mm and 200 mm focal length lenses should be displaced by approximately 40 mm Make the necessary horizontal and vertical adjustm
126. e terms and condi tions of the sales order shall prevail Unless otherwise specified all parts and assemblies manufactured by Spectra Physics are unconditionally warranted to be free of defects in workmanship and materials for a period of one year for mechanical and electrical compo nents and 90 days for optics following delivery of the equipment to the FO B point Liability under this warranty is limited to repairing replacing or giving credit for the purchase price of any equipment that proves defective during the warranty period provided prior authorization for such return has been given by an authorized representative of Spectra Physics Spectra Physics Quanta Ray MOPO HF Optical Parametric Oscillator will provide at its expense all parts and labor and one way return shipping of the defective part or instrument if required In warranty repaired or replaced equipment is warranted only for the remaining unexpired portion of the original warranty period applicable to the repaired or replaced equip ment This warranty does not apply to any instrument or component not manufac tured by Spectra Physics When products manufactured by others are included in Spectra Physics equipment the original manufacturer s war ranty is extended to Spectra Physics customers When products manufac tured by others are used in conjunction with Spectra Physics equipment this warranty is extended only to the equipment manufactured by Spectra Physics
127. e wavelength dis play format Setting Large Letters Small Letters SIGNAL Signal Idler IDLER Idler Signal FDO FDO Signal F MODE NORM MICRO allows you to select a 6 digit NORM or 7 digit MICRO wavelength display format The latter is used when more accuracy is required F4 MODE nm cm allows you to set the wavelength display units as nm or cm F M OSC 1 2 4 8 16 allows you to set the display gain for the master oscillator to 1 2 4 8 or 16 times to increase the sensitivity of the bar graphs F P OSC 1 2 4 8 16 allows you to set the display gain for the power oscillator to 1 2 4 8 or 16 times to increase the sensitivity of the bar graphs Shows MO and PO output power Select the SERVICE1 menu and their reference and relative values a N OPERATE SERVICE1 OPMOD IDL SGWVL 500000 MOPWR 0 POPWR 15 SETUP1 MOSET 16547 MOVAL 16547 SETUP MONITOR1 POSET 15482 POVAL 17399 INFO FRMWRE RESET INSTALL WL MONITOR y Displays system serial Allows you to update Allows you to run a self number software version the system firmware diagnostic to recalibrate the and track date PCMCIA card wavelength grating setting Figure 6 4 The Servicel Menu The Servicel menu displays important status information regarding oper
128. ected from the UVBS Two screws fasten the beam dump to the base plate There are no adjustments MO TM master oscillator turning mirror provides adjustment to align the incoming beam from UVBS and direct it to MO TM The mount is fas tened to the base plate by two screws and the mount is slotted so it can be moved forward and backward Although the mirror can be cleaned in place it can be removed by removing 4 screws of the retaining ring with an Allen ball driver and removing the mirror with the retaining ring The optic is flat so there is no set orientation and it is spring loaded against 3 balls for repeatability after removal There are vertical upper and horizontal lower alignment knobs for directing the beam MO TM master oscillator turning mirror provides adjustment to direct the beam from MO TM to the telescope through pin hole PH when present The mount is fastened to the base plate by two screws and the mount is slotted so it can be moved forward and backward Although the mirror can be cleaned in place it can be removed by removing 4 screws of the retaining ring with an Allen ball driver and removing the mirror with the retaining ring The optic is flat so there is no set orientation and it is spring loaded against 3 balls for repeatable seating There are vertical upper and horizontal lower alignment knobs for directing the beam PH pin hole is used for alignment purposes only There are several o
129. ection closest to the center of PH is displaced to the left hand side by about 30 mm Note that both reflections miss the aperture mount completely Figure A 6 PH13 30 mm k Pinhole Retroreflections from the crystal surfaces Figure A 6 The HeNe beam retroreflections from the crystal for case B Case C The crystal is marked L Perform the same adjustments as in Case A Parasitic oscillations can be observed when the surface of the crystal is nearly perpendicular to the incident beam Under these conditions the crystal surfaces may provide enough reflection and feedback in the appro priate direction to induce oscillation within the crystal Parasitic oscilla tions are undesirable as they have broad linewidths cannot be tuned and may cause optical damage This completes the master oscillator installation 1 Insert the crystal assembly the BBO crystal placed between two alu minum crystal holders into the crystal mount 2 Turn the screw in the crystal assembly counterclockwise to spring load the assembly in the crystal mount Important Make sure the power oscillator c axis is oriented as depicted in Figure A 3 This completes the power oscillator installation Quanta Ray MOPO HF Optical Parametric Oscillator A 6 Appendix B Scope Overview The RS 232 IEEE 488 Interface This appendix explains how to operate the MOPO HF system from a remote source using either the opti
130. ed for the nonlinear interaction e Low absorption over the entire tuning range e Ability to be fabricated in useful sizes e No significant degradation with time The only material fitting these criteria is BBO and it has only been in recent years that high quality BBO crystals have been available in useful sizes necessary for the commercialization of OPO devices The MOPO HF is a coupled dual oscillator system In this scheme a high energy power oscillator is injection seeded with the narrow linewidth out put from a master oscillator This enables the coupled oscillator system to produce narrow bandwidth high energy tunable coherent radiation The acronym MOPO master oscillator power oscillator is derived from this design concept The MOPO HF is a pulsed optical parametric oscillator OPO which uses type I phase matched beta barium borate BBO as the nonlinear gain medium BBO is a negative uniaxial crystal with intrinsic birefringence properties that are used to achieve critical phase matching Tuning the MOPO output is therefore accomplished by rotating the OPO crystal with respect to the optical axis of the resonator angle tuning The master oscillator design uses a grating in grazing incidence geometry to produce a narrow linewidth output There are three optical elements which form the optical resonator a broadband high reflector a high modu lation holographic grating designed to provide suitable diffraction effi cien
131. ed in a pump photon at frequency is transferred to two other photons the sig nal wave and 1 the idler wave in such a way as to satisfy the energy con version law 0 0 0 1 Or in terms of wavelength IA MA EA 2 By placing the parametric gain medium BBO in an appropriate resonant cavity oscillation at the signal and or idler wavelength can be obtained In OPOs the gain can be large enough that no signal input wave is necessary The signal will grow from quantum noise in the crystal Both the signal wave and the idler wave can be resonated simultaneously doubly reso nant or individually singly resonant The Quanta Ray MOPO HF series is designed such that both cavities the master and power oscillators are singly resonant over the signal wavelength range 3 1 Quanta Ray MOPO HF Optical Parametric Oscillator J Variable oo nn 0 450 690 nm Signal 0 355 nm AS 0 730 1700 nm Idler Pump Beam Figure 3 2 Parametric Amplification to Generate Tunable Output from 450 nm to Beyond 1700 nm The output of an OPO is very similar to that of a laser The signal and idler beams exhibit strong coherence are highly monochromatic and have a spectrum consisting of one or more longitudinal modes Although similar in structure and operation to that of a laser the OPO obtains gain from a nonlinear conversion rather than an atomic transition Because of this dif ference the OPO has no gain storage
132. elengths Nitroeen purging is recommended to avoid water absorption while tuning and to improve system cleanliness point and can Service Requirements Electrical service Mechanical Specifications Size Weight MOPO HF Digital controller Environmental Specifications Description 115 230 V 5 3 A 50 60 Hz single phase See Outline Drawings 84 kg 185 Ib 10 kg 22 Ib The environmental conditions under which the MOPO HF system will function are listed below Indoor use Altitude Temperatures Maximum relative humidity Mains supply voltage Insulation category Pollution degree up to 2000 m 10 C to 40 C 80 non condensing for temperatures up to 31 C do not exceed 10 of the nominal voltage for the controller II 2 Quanta Ray MOPO HF Optical Parametric Oscillator Outline Drawings 46 30 1176 0 SG Spectra Physics amp Quanta Ray 6 59 32 00 7 84 167 4 812 8 186 4 Side View 26 55 2 00 674 4 a 50 8 15 31 8 72 10 73 4 18 5 10 338 9 221 5 272 5 106 2 cad 11 11 9 OC 9 A 712 28252 712 To 180 8 A 180 8 227 22 00 57 7 ka 558 8 Input End View Output End View MOPO HF Head pe 17 00 x 14 30 431 8 363 2 A 100000000000 OOOO OUO DDR 5 25 H B OOO LOBO NAO DOO 133 4 O Jogoo Y B Y Gy spscmestydce
133. en these modes are selected and lists them in the order in which they are discussed in fuller detail later in this chapter MODE KEYS 1 OPERATE SETUP MONITOR OPERATE1 SETUP1 MONITOR1 Y Y OPERATE2 SETUP2 Y Y SERVICE1 REMOTE Quanta Ray MOPO HF Optical Parametric Oscillator A Brief Description The following is a short description of each menu A complete description of each follows later in this chapter The Operatel Menu page 6 11 is displayed when the system is first turned on and any time the OPERATE button is pressed 500 0000 cL 1220 814nm It displays e Signal large and idler small output wavelength if NORM is selected in the Operate2 menu or e Idler large and signal small output wavelength if IDLER is selected in the Operate2 menu or e MOPO HF FDO large doubled output wavelength and MOPO HF source wavelength small if FDO was selected in the Operate2 menu e The progression of the scan as a bar graph left start right done The MOPO HF mode setting L Track Lock The function buttons allow initiation of e a GOTO automatically goto a selected wavelength e a SCAN begin a scan from one wavelength to another e aMOVE manually move a selected wavelength using the up down but tons e a RECALL of the previous settings e a SAVE of the present settings The Operate2 Menu page 6 13 is displayed when the OPE
134. ength the scan proceeds toward the ending wavelength stopping every 1 nm along the way to sample the beam power It then writes the best value to the table This continues until the table is com plete This routine can take quite a while to run depending on the size of the scan range Please refer to the Automatic Table writing Procedure on page 6 33 for a complete explanation of this method OPO_AUTO performs an automatic table writing routine for the power oscillator based on the beginning and ending scan values set in the Setup menu If this routine detects that there is no similar table present for the master oscillator it will create one for the MO as well Starting with the beginning scan wavelength the scan proceeds toward the ending wavelength stopping every 1 nm along the way to sample the beam power It then writes the best value to the table This continues until the table is com plete This routine can take quite a while to run depending on the size of the scan range Please refer to the Automatic Table writing Procedure on page 6 33 for a complete explanation of this method F4 ADJUST becomes available to allow activation of the appropriate adjustment environment once DEVICE and METHOD are selected Displayed is the current device set point the current device position and the wave length F SET BASE allows you to run a routing that sets a base value for the PO PD refer to the Threshold Table
135. ent operating parameters into non volatile memory as setup record 43 GOSUB WriteMopo PRINT Recalling parameter setup TotalLoops total loops PRINT Cmd recall 4 Load setup parameters record 4 from non volatile memory GOSUB WriteMopo GOSUB WaitFiveSeconds are interrupts dead during read routinely hangs w o this wait NEXT multiloop GOTO TotalLoop makes an infinite loop program PRINT End of Sample Program END End of Sample Program B 23 Quanta Ray MOPO HF Optical Parametric Oscillator NK KKK KKK KKK KR KKK KKK KE KK KKK KKK KKK KKK KKK KKK ck ck Ck ck ck Ck KKK ck ko KKK ko ko kx KK y SUBROUTINES Vk oko ce ce ce ce e ce c ke ce kk ce ck ck Cock ck ck ck ck ck Ck ck ck ck ck ck ck Ck ck ck Ck ko sk ck ko ko Sk Ck ko ko ko ko ok ox ReadSetup PRINT Verifying setup PRINT Cmd source begin GOSUB WriteMopo GOSUB ReadMopo Responsel VAL Response Cmd source end GOSUB WriteMopo GOSUB ReadMopo Response2 VAL Response Cmd source rate GOSUB WriteMopo GOSUB ReadMopo Response3 VAL Response Cmd source shots GOSUB WriteMopo GOSUB ReadMopo Response4 VAL Response Cmd source scans GOSUB WriteMopo GOSUB ReadMopo Response5 VAL Response Cmd source incr GOSUB WriteMopo GOSUB ReadMopo
136. ents of the positive lens mount position re overlap the pump and HeNe beams on the busi ness card at the diagnostic output port Remove PH Remove the business card at the diagnostic output port Place the macor aperture in its appropriate location on the base plate Make sure it is centered on the beam Establish collimation of pump beam a If necessary adjust the position of the positive lens until the beam appears collimated Estimate the degree of collimation by viewing the pump beam at a position just past the negative lens and in front of the beam dump Make sure the beam is still centered on the HeNe beam It should not be clipping the edge of the BBO com pensator or optical mount Since the beam will have more convergence character when run in Q SWITCH mode it is recommended that the negative and positive lens displacement be adjusted so that the beam appears slightly divergent b Place a power meter at the signal output port Place an appropriate beam block behind VDC Also remove any pinholes in the beam paths c Insert a suitably thick hex wrench l sin or a 10 32 screw between the vertical adjust push plate and the main portion of the output coupler mount This will suppress oscillation in the PO in the subsequent steps d Change to Q SWITCH mode Take mode burns just after the negative lens and in front of the beam dump Unexposed Polaroid film works well for mode burns Place the film in a plastic ba
137. er 4 Turn the key switch on the PRO Series power supply to the OFF posi tion and remove the key Leave the circuit breaker switch ON so that the HG and injector seeder heaters stay warm This will reduce the warm up period next time 5 Turn off the MOPO HF FDO controller This completes the shut down procedure for day to day use In the event the unit is to be moved or left off for a long period of time turn off the cir cuit breaker on the PRO Series power supply Operating the Control Electronics Use the MOPO HF controller to access MOPO HF FDO operational setup monitoring and service functions Note if you purchased the MOPO HF FDO unit after the MOPO HF the Spectra Physics service engineer that installed the MOPO HF FDO also reconfigured the firmware to expand the control capability of the MOPO HF electronics unit to include those for the FDO The MOPO HF and MOPO HF FDO functions are accessed in the same manner Ten buttons are used for operating the MOPO HF FDO controller Figure 6 1 Three buttons to the left of the display allow selection of the Operatel Operate2 Servicel Setupl Setup2 Remote or Monitor menus The Setup menus allow you to set scan parameters and choose vari ous table algorithms for controlling the position of system crystals The five buttons on the bottom are soft keys They select and control var ious functions depending on which menu is active and which function was 6 5 Quanta
138. er shown Figure 6 2 The Operatel Menu The Operatel menu appears when the system is first turned on From other menus pressing the OPERATE button at any time returns you to this menu Pressing it a second time brings up the Operate2 menu A third push brings up the Servicel menu Pushed one more time will return you to the Operatel menu This menu allows you to set the MOPO HF wavelengths directly to initiate a scan to manually tune the wavelength output to recall one of 20 stored settings and to save the present settings as one of the 20 stored settings Quanta Ray MOPO HF Optical Parametric Oscillator 6 12 The Display When SIGNAL has been selected in the Operate2 menu the large number in the upper right hand box is the signal wavelength and the idler is the small number If IDLER was selected these numbers are reversed If FDO was selected the large number is the MOPO HF FDO doubled wavelength and the small one is the signal The horizontal bar indicates the status of the current scan with start to the left and end to the right This bar is displayed only when a scan is in progress An L in the right window denotes that MOPO HF track mode is selected The Function Keys F GOTO XX allows the operator to have the system automatically move to the wavelength displayed below GOTO Press F and use the Setting Numeric Values procedure on page 6 7 to set the wavelength value desired then hold F i
139. erfaces Future accessories bay provides room for future options Q SWITCH SYNC connector provides connection to the Q SW SYNC con nector on the PRO Series power supply which supplies a sync signal to the controller MOPO AUTOTRACK connector provides connection to the MOPO HF interface on the side panel for command control 4 11 Quanta Ray MOPO HF Optical Parametric Oscillator 4 12 Chapter 5 Installation and Alignment The following installation procedure is provided for reference only it is not intended as a guide to the initial installation and set up of your MOPO HF Please call your service representative to arrange an installation appoint ment which is part of your purchase agreement Allow only personnel qualified and authorized by Spectra Physics to install and set up your MOPO HF system Danger The use of controls or adjustments or the performance of procedures Laser Radiation other than those specified herein may result in hazardous radiation exposure Installation sionals and should not require alignment in the field Furthermore the MOPO HF generates an enormous amount of optical power that can cause damage and even injury Therefore do not attempt to align the laser yourself you may void your warranty Instead call your Spectra Physics service representative Danger W Your MOPO HF was aligned at the factory by specially trained profes Materials Needed e Two alignment pinhole ap
140. ertical top and horizontal side alignment knobs for directing the beam Two screws can be loosened to move the optic vertically and 2 screws fasten the mount to the base plate Slotted holes allow the mount to be moved forward and backward in the beam PO TM power oscillator turning mirror receives the residual beam from PO TMg and directs it to beam dump MBD The lens is spring loaded against 3 balls for repeatable seating There are no vertical or horizontal adjustments for directing the beam Two screws fasten the mount to the base plate MBD mini beam dump absorbs the residual PO beam from PO TM Two screws fasten the beam dump to the base plate There are no adjust ments There are no indicators on the MOPO HF There are three connections on the MOPO HF side panel for attaching the unit to the MOPO controller see Figure 4 2 Optional FDO connector provides control signals to and from the optional FDO frequency doubler Refer to the FDO User s Manual for con nection information MOPO AUTOTRACK connector provides control signals to and from the MOPO HF controller SINE DRIVE connector provides control signals from the controller to the sine drive stepper motor Controls Indicators and Connections a Quanta Ray Optional FDO Autotrack Sine Drive Connector Connector Connector Figure 4 2 MOPO HF Connectors Right Side View The MOPO HF Digital Controller Front P
141. ertures e Black pinhole aperture e Three beam dumps one large beam dump e g BD 5 two small beam dumps with an input port height at 9 21 cm 3 63 in above the MOPO HF base plate e One or more white business cards In order to see the 355 nm beam in the following procedures place a viewing card over one of the pinhole apertures Do this by punching a 1 mm dia hole through the center of a business card Tape or glue the card over the aperture allowing the beam through the alignment pin hole Alternatively place a white UV fluorescent label over the aper ture and punch a hole in the center where the pinhole is Provided with system 5 1 Quanta Ray MOPO HF Optical Parametric Oscillator Initial Setup 5 2 Right angle turning prism assembly The assembly should include the necessary hardware to place the cen ter of the optic approximately 3 5 in off the base plate See Figure 5 1 e g Newport SP 2 and VPH 2 LEN Mirror Mount 2 Post Holder Figure 5 1 A Typical Right angle Turning Prism Assembly HeNe laser gt 5 mW recommended Hex wrench set 5 8 in and 16 in wrenches Infrared IR card Infrared high pass visible cut off filter e g Schott RG695 PRO Series Model 230 10 or higher laser configured for 355 nm out put Pen or pencil Ruler Uncoated beamsplitter fused silica BK 7 or equivalent Mounting hardware is required to locate the optic approximately 7
142. ery is not secured by the holder and will fall out of the holder as soon as it is no longer retained by the sides of the card If it falls onto the controller motherboard it can short traces or components and ruin the motherboard Be very careful hang onto the battery as you pull it out Caution W Replacing the PCMCIA Card Battery 1 With the controller power on and the PCMCIA card in the unit either loosen the screw Mitsubishi or Panasonic or slide the latch that retains the battery Do not drop the screw on the motherboard 2 Observe the polarity of the battery as you remove it it is possible to install the battery backwards in the Panasonic card There is a sign on the battery on its positive side the side without the seam The sign should face away from the front of the controller 3 Install the new battery observing its polarity Fasten the holder in place with the screw or slide the retaining latch into place 5 Place a piece of tape or Avery label on the PCMCIA card and mark on it the date of installation Remember to replace the battery approximately every 2 years Please dispose of the battery in accordance with local laws and regula tions This completes the procedure for replacing the battery in the PCMCIA card C 3 Quanta Ray MOPO HF Optical Parametric Oscillator C 4 Appendix D Manually Controlling the Crystal Stage The Autotrack pc board in the MOPO HF control
143. et S or S to the BLUE position toward you to rotate the crystal toward the blue wavelengths or to the RED position away from you to rotate it toward the red wavelengths When set to manual once the slide switches are placed in the desired setting press the black button S or Sg to move the motormike When you are done moving the motormike s manually remember to set switch es S and or Sg back to COMPUTER before going back to normal operation Quanta Ray MOPO HF Optical Parametric Oscillator D 2 Appendix E Determining Telescope Lenses for the PO The following procedure is provided so you can select the proper lens com bination for your power oscillator PO telescope if your system has not been previously setup and aligned or has had its configuration changed 1 Measure the 355 nm energy in the power oscillator leg a Set the PRO Series laser to Q SWITCH OFF b If present remove the PO beam dump from in front of PO TM c Set the PRO Series laser to LONG PULSE mode d Remove PO TM e Remove the plug from the output diagnostic port f Place a power meter on the optical table in front of the diagnostic output port left most porthole on the input side of the MOPO HF Refer to Figure E 1 Pick off Prism PO TM removed Beam Dump MBD PO TM PO TM BBO pote A ka sae es tt A X Power Oscillator Reference Beam Pump In Master Osc
144. ey are independently optimized These optimized values are stored in a peak table for various wavelengths over the entire tuning range The threshold is calculated by taking a fixed percentage of the peak baseline difference and adding that to the baseline value 1 Set the system to track mode a From the Monitor menu press the MOPO button then use the up down buttons to scroll to TRACK b Press and hold the MOPO button until it beeps to activate your selection 2 From the Setup menu set the begin and end scan wavelengths to the desired range e g 450 690 nm From the Operatel menu use Setting Numeric Values procedure on page 6 7 to set the BEGIN and END wavelength values 3 Run the base line routine From the Setup2 menu press and hold the SET BASE button until it beeps This allows the routine to run until it is complete 4 When the base line routine is finished run the peaking routine a Press and hold the SET PEAK button until it beeps The following menu appears OPERATE2 M_OSC P OSC 500000 0 REMOTE H 1428 H 0 MONITOR1 MO_CRYS PO_CRYS b Press the CONT button at each query wavelength to move to the next wavelength If the tables are accurate and tracking is active the system should opti mize the MO and PO crystal positions at each wavelength c After the CONT button is pressed at 690 nm a SAVE button should appear d Press the SAVE button unti
145. f these and they can be removed and placed in several positions for the dif ferent stages of alignment The number designates a position rather than a particular pin hole mount Controls Indicators and Connections MO Telescope is made up of the MO PL and MO NL described below and is used to set the diameter size of the beam MO PL master oscillator positive lens is the input end of the MO tele scope see above It is mounted on a spring loaded slide and a micrometer provides fine adjustment for setting the separation between the two lenses Although the lens can be cleaned in place it can be removed by removing the 4 screws of the retaining ring with an Allen ball driver and removing the lens with the retaining ring The lens is spring loaded against 3 balls for repeatable seating There are no vertical or horizontal adjustments for directing the beam The mount is fastened to the base plate by 2 screws MO NL master oscillator negative lens is the output end of the MO tele scope see above It is firmly mounted to the base plate by 2 screws but the holes are slotted to allow for some minor horizontal adjustment Two screws can be loosened for vertical adjustment Although the lens can be cleaned in place it can be removed by removing the 4 screws of the retain ing ring with an Allen ball driver and removing the lens with the retaining ring The lens is spring loaded against 3 balls for repeatable seating There are no ver
146. f the spectrum Scanning through the degeneracy range is not permitted and a warning to this effect will be displayed The degeneracy range is 690 to 732 nm for the MOPO HF and 345 to 366 nm for the MOPO HF FDO When present a DL in the left window denotes the MOPO HF FDO track mode is selected DT denotes table mode is selected An L in the right window denotes the MOPO HF track mode is selected No designa tion denotes MOPO HF table mode is selected The SSS procedure is not used with this menu Use the Selecting Numeric Values procedure on page 6 7 to set the various function values in this menu Please note you cannot set the BEGIN and END wavelength to a number outside the range allowed for the selected MODE the SIGNAL IDLER or FDO designated by the wavelength displayed in large digits If by error you try to do so the controller will beep and will not change the value of that digit Make sure the wavelength settings desired matches the mode you selected earlier via the OPERATE1 menu The Display When MODE NORM has been selected in the Operate2 menu the large number in the upper right hand box is the signal wavelength and the idler is the small number If IDLER is selected these numbers are reversed If FDO is selected the large number is the MOPO HF FDO doubled wavelength and the small one is the signal The Function buttons F SCANS XXX sets the number of consecutive scans to be performed
147. fer to Figure 6 11 and to provide you con trol of the scan as it progresses A horizontal bar graph displays the 6 25 Quanta Ray MOPO HF Optical Parametric Oscillator percentage of scan completed and the wavelength display shows the progress of the signal or idler output or if MODE in the Operate2 menu is set to FDO the doubled signal or idler output Fraction of current Current MOPO or FDO output scans complete Current Signal or Idler output OPERATE OPERATE1 500 000 SCAN 1 LI SETUP1 SETUP MONITOR1 1220 814nm ABORT HOLD SCAN SCAN MONITOR F4 Fo F3 Fu Fs Abort scan and Temporarily halt return to Operate1 menu scan Figure 6 11 Scan in Progress 9 If you wish to pause the scan press the HOLD SCAN button To resume the scan press the RESUME SCAN button 10 If you wish to abort the scan altogether press the ABORT SCAN button You will be returned to the Operatel menu When the scan completes the system moves back to the starting wave length and returns to the Operatel menu If you aborted the scan the sys tem will remain where is was when you pressed it Operating at Fixed Wavelengths 6 26 1 Set the system for track mode If track mode is already selected an L
148. ference beam alignment estab lished during calibration To re establish the initial alignment make minor adjustments of R TM while viewing the retro reflec tion on the pinhole This should be sufficient to re establish the ini tial alignment c A beam displacement of more than 2 mm might be due to a minor misalignment of the tuning mirror and or grating In most cases the error corresponds to a linear shift in the grating table This may be compensated for by a slight vertical and or horizontal adjust ment of the tuning mirror Figure 5 7 Vertical Pitch Roll Adjustment Adjustment Set Screw Used to lock the adjustment screw Horizontal Adjustment Figure 5 7 Tuning Mirror Adjustments 18 19 Adjust the HeNe sheet polarizer so the reference beam is vertically polarized for overlap purposes it is important to use a vertically polarized refer ence beam since the PRO Series laser is vertically polarized As explained in Step 2 of this procedure changing the polarization of the reference beam will result in a displacement of the beam which exists the crystal Do not try to compensate for this with alignment This effect is a result of the birefringence of the BBO crystal and is taken into account in the alignment procedure Verify changing the polarization does not result in misalignment of the reference beam through the pinhole If it does direct the beam through a different portion of the sheet polarizer
149. fter removal There are vertical upper and horizontal lower alignment knobs for directing the beam Controls Indicators and Connections PO TM power oscillator turning mirror provides adjustment to align the incoming beam from PO TM and direct it to PO TM The mount is fas tened to the base plate by two screws and the mount is slotted so it can be moved forward and backward Although the mirror can be cleaned in place it can be removed by removing 4 screws of the retaining ring with an Allen ball driver and removing the mirror with the retaining ring The optic is wedged so there is a set orientation but there are no markings on the mirror for orientation This rotation setting is set during the alignment procedure The mirror is spring loaded against 3 balls for repeatability after removal There are vertical upper and horizontal lower alignment knobs for directing the beam PO TM power oscillator turning mirror reflects the incoming beam from PO TM back onto it but at a slightly different angle so that PO TM then reflects the bounced beam onto PO RM The mount is fastened to the base plate by two screws Although the mirror can be cleaned in place it can be removed by removing 4 screws of the retaining ring with an Allen ball driver and removing the mirror with the retaining ring The optic is flat so there is no set orientation and it is spring loaded against 3 balls for repeatability after removal There are vertical
150. g To do so make the end wavelength the beginning point of a new scan the end point remains the same as before then run the Lagrangian Table writing Procedure on page 6 31 to get the system back within the required parameters for automatic table writing Once this procedure is complete re run this automatic table writing routine using the same scan setup that was used for the Lagrange routine This completes the automatic table writing procedure Chapter 7 Maintenance Preventative Maintenance The MOPO HF top cover protects the internal components from out side contamination and prevents unwanted stray optical radiation from escaping the system The MOPO HF should always be operated with the top cover in place e Inspect daily all windows for contamination or damage Windows should be cleaned with spectroscopic or electronic grade methanol or acetone and lens tissue any time contamination is suspected or observed Damaged windows should be immediately replaced e tis recommended the user annually check the safety features of the pump laser as well as the MOPO HF optics to ensure safety is main tained see Chapter 2 Laser Safety for details Cleaning of Laser Optics Losses due to unclean optics which might be negligible in ordinary optical systems can disable a laser Dust on mirror surfaces can reduce output power or cause total failure due to damage Cleanliness is essential and the maintenance techniques
151. g loaded against 3 balls for repeatable seating There are no vertical or horizontal adjustments for directing the beam The mount is fastened to the base plate by 2 screws PO NL power oscillator negative lens is the output end of the telescope see above It is firmly mounted to the base plate by 2 screws but the holes are slotted to allow for some minor horizontal adjustment Two screws can be loosened for vertical adjustment Although the lens can be cleaned in place it can be removed by removing the 4 screws of the retaining ring Quanta Ray MOPO HF Optical Parametric Oscillator Indicators Connections 4 8 with an Allen ball driver and removing the lens with the retaining ring The lens is spring loaded against 3 balls for repeatable seating There are no vertical or horizontal adjustments for directing the beam MA Macor ceramic aperture reduces the diameter of the beam from the PO NL so the beam will fit through the clear aperture of the power oscillator BBO crystal Two screws can be loosened to move the aperture vertically and two screws fasten the mount to the base plate PO TM power oscillator turning mirror receives the beam from PO NL and directs it to PO TMs where the power oscillator beam is mixed with the seed beam Although the mirror can be cleaned in place it can be removed by removing 4 screws of the retaining ring with an Allen ball driver and removing the mirror with the retaining ring There are v
152. g the diameter of the seed beam A single clamping screw on top of the negative lens allows you to move it in order to adjust the separation between the lenses Two screws fasten the mount to the base plate Power Oscillator PO BBHR power oscillator high reflector allows the seed from the tele scope to pass through but reflects light from the power oscillator side back through the PO BBO crystal A white flag capture any stray light from the PO BBO crystal as it rotates There are vertical upper and horizontal lower alignment knobs for directing the beam Two screws can be loos ened to move the optic vertically and 2 screws fasten the mount to the base plate and slotted holes allow the mount to be moved forward and backward in the beam PO TM power oscillator turning mirror allows the seed beam to pass through but turns the amplified power oscillator beam from the PO BBO crystal and directs it to turning mirror PO TM The optic is wedged so there is a set orientation but there are no markings on the mirror for orientation Orientation is set during the alignment procedure Although the mirror can be cleaned in place it can be removed or rotated using an Allen ball driver to loosen the 3 D cams that hold it in place Loosen to rotate the mirror turn the cams to release the mirror The mount is spring loaded against 3 balls for repeatable seating There are vertical upper and horizontal lower alignment knobs for directing
153. g to prevent ablated material from getting onto optical components f Evaluate the collimation of the beam by comparing the diameter of the mode burns g Since the beam tends to spread out spatially with most of the energy in the central portion it is recommended that the beam exhibit a slight amount of divergence If the beam does not exhibit the desired amount of divergence character perform the steps out lined below i Change to LONG PULSE mode ii Place a business card target in the beam path in front of the beam dump 5 35 Quanta Ray MOPO HF Optical Parametric Oscillator 111 Mark the location of the beam iv Adjust the positive lens mount position in the direction neces sary to attain the desired degree of collimation see Note below the negative lens If the beam is converging move the positive lens Note a If the beam divergence is too great move the positive lens away from toward the negative lens v Verify the beam is roughly centered on the target in front of the beam dump vi Remove the target vii Turn to Q SWITCH mode as described above and take mode burns again viii Repeat this procedure until desired degree of collimation is achieved 21 Change to LONG PULSE mode 22 Place PH back onto the base plate 23 Re check the overlap between the pump and HeNe beams a Remove the beam block placed in front of the signal output port in order allow the reference HeNe beam to pass uno
154. ght to establish an align ment reference for the optical cavity since the polarization of the reso nated signal wave is horizontally polarized Figure 5 6 3 Align the reference beam to pinholes PH and PH Figure 5 19 R TM PH OC PH VDC Z N HeNe a A A BBO Comp PO BBHR Power Oscillator A ee A Removed 9Wer USC VDC PH PH R TM Master Oscillator Figure 5 19 Reference beam alignment for the power oscillator For clarity some components are not shown a Place an aperture assembly on the dowel pins at PHg and secure it to the base plate with a 10 32 screw 5 25 Quanta Ray MOPO HF Optical Parametric Oscillator 5 26 b Place alignment mirror R TM approximately 1 foot 30 cm in front of PH The space between the MOPO HF and the routing mirror leaves room for the placement of a power meter c Place an aperture assembly on the dowel pins at PHs Adjust R TM to center the reference beam on PH then adjust R TM to center the reference beam on PHs e Iterate the last step until the beam is centered through the two pin holes Place aperture assemblies on the dowel pins at PH and PH Adjust VDC to center the beam on PH Adjust VDC to center the beam on PH Iterate the last two steps until the beam is centered through the two pinholes Reverse the pinholes in PHg so the flat side faces the BBO crystal This allows retroreflections from the oscillator optics to be seen dur
155. gnment knobs for directing the beam Two screws can be loosened to move the optic vertically and 2 screws fasten the mount to the base plate Slotted holes allow the mount to be moved forward and backward in the beam Compensator compensates for the beam offset caused by the rotation of the BBO crystal by rotating in the opposite direction A single screw holds it in its holder and the holding arm rotates the crystal via a motor driven by the MOPO controller The entry beam comes from PO TM and is directed toward the output coupler OC There are no other adjustments on the com pensator mount BS beam splitter directs part of the output beam to the power oscillator photo detector which monitors power oscillator output The optic is wedged so there is a set orientation but there are no markings on the mirror for orientation This rotation setting is set during the alignment procedure Although the beam splitter can be cleaned in place it can be removed by unscrewing the bezel and grabbing the barrel with the optic There are ver tical top and horizontal side alignment knobs for directing the beam Before removing the optic however it is prudent to mark the rotation posi tion of the lens so that it is easy to put it back the way it was VDC visible dichroic removes any residual visible wavelengths from the output beam from the output coupler then directs the beam toward VDC Although the mirror can be cleaned in place
156. h the default settings shown If you have an IBM PC compatible computer you will have to install a GPIB controller card in it There are many brands of GPIB controller cards and you may use any one of them that gives your computer GPIB controller capability If you use the National Instruments GPIB PC IVIIA interface card you can use the dip switch and jumper settings shown in Table B 1 The GPIB device address of the MOPO HF system is set at the factory to address 15 If this address conflicts with the address of another instrument on the GPIB bus select another GPIB address for the MOPO HF Refer to Selection below for instructions on how to select another GPIB address The RS 232 IEEE 488 Interface Selection RS232 IEEE LOCAL Use the Remote menu to select the system control source The default set ting from the factory is the front panel or LOCAL but the setting can be changed so that the MOPO HF can be controlled from a serial device such as a terminal or a personal computer configured as a terminal or an IEEE 488 parallel control source When one of the remote interfaces is the con trol source LOCAL is displayed in F to allow the user to return control to the front panel Before the RS 232 or the IEEE 488 interface can be used it must first be selected and its parameters set from the Remote menu See Chapter 6 Operation The Remote Menu 1 Press the MONITOR menu key until the Remote menu is displayed
157. h then passes through the idler output port The signal beam is reflected and directed near normal incidence onto another broadband dichroic which removes residual idler and directs it through the signal output port Figure 3 7 3 5 Quanta Ray MOPO HF Optical Parametric Oscillator Pump In Pump Out Crystal Output Broadband Broadband High Reflector Compensator Coupler Signal and Dichroic Idler Output MA BBO Bad ik gt Idler Seed Radiation Xtal RE m menie iiim gt Signal 355 nm Residual Dichroics Idler Broadband Dichroic Figure 3 7 Power oscillator cavity geometry Illustration shows separation of signal and idler output beams with broadband dichroic mirrors The Seeding Process The master oscillator output is obtained from the zeroth order mirror reflection from the diffraction grating The beam is directed onto a routing mirror STP which has an IR absorbing filter to remove the idler This minimizes the chance of optical damage by reducing the total energy on the mirror The remaining signal beam is directed through an uncoated beam splitter The reflection from the beam splitter is used to monitor the opera tion of the master oscillator Another routing mirror STP is used to direct the beam through an upsizing telescope and onto the backside of the power oscillator broadband high reflector PO BBHR The energy levels that leak through the high reflector are s
158. has been written the seeded unseeded ratio may be too small By adjusting the half wave plate this ratio may be increased Keep in mind the trade off associated with this adjustment is a reduction in output energy General operation hints e Optimal performance can be obtained by writing a small table over a region of interest shortly before an experiment is performed e On a daily basis prior to operating the MOPO HF make sure the 355 nm output is peaked and stable If necessary adjust the HG Daily Start Up Procedure This short procedure is provided to minimize your daily start up efforts The MOPO HF controls and display menus that are referred to here are discussed later in this chapter or are covered in your FDO 970 User s Man ual This procedure assumes the system was used recently and has not been moved since that time The MOPO HF FDO controller should be off do not turn it on until told to do so 1 If frequency doubling verify TP is in its proper position for use with the FDO If frequency doubling is not desired make sure TP is moved to its parking lot position so that it does not block the signal and or idler beams from exiting their respective ports 2 Verify the cooling water for the PRO Series laser is on 3 Verify the seeder on the pump laser is turned to ON and the piezo is set to AUTO 4 Turn on the PRO Series laser and set it to LONG PULSE mode Allow the laser to warm up for 15 to 30 minutes 5 Turn o
159. he lens mount ii Vertical adjustment Use a 16 in hex wrench to adjust the two downward facing screws on the side of the mount iii Horizontal adjustment Use a 16 in hex wrench to adjust the side facing screw on the side of the mount m Remove PH from the beam path Focused back reflection from MO PL can easily damage MO TM or MO TM When finished aligning the MO telescope in this step slightly adjust MO PL horizontally just until the focused back reflection is directed to the teflon ring of MO TM or if that is not possible of MO TM It is not necessary to realign the beam to PH o 11 Establish collimation of the PRO Series 355 nm MO pump beam a Remove MO BBHR from its standard location on the base plate and place it in its alignment location on the left hand side of the grating tuning mirror pair so it retro reflects the reference beam back onto itself Figure 5 9 5 15 Quanta Ray MOPO HF Optical Parametric Oscillator Pump in Long Pulse mode of operation R TM To PO Power Oscillator MO BBHR Reference Beam removed HeNe Laser MO BBHR Master Oscillator alignment location BBO PH PH R TM Y po 2 E Installation Aperture Figure 5 9 Placement of MO BBHR for pump beam alignment Pump In 355 nm Power Oscillator Master Oscillator Pick off MO TM5 Prism SZ A SS PHi3 Beam Dump Pump Out
160. hole c Remove the pinhole from in front of UVBS Installation and Alignment MBD PO TM PO Y 2 i2 RM AP gt PH PO PL PO NL PH Z Y PO TM PH DI as OC BS PH voc s COMP d eee E NE gt p Idler Beam Out PH R O O Z YT i HW SEHA PO TM PO TM AN AN gt Signal Beam Out p To VDC BH BH MO PD 5 e PH A MO TM MO TM MO BBHR Y Grating PH lus Y K E is ES UV 355 nm x Pump BOAT gt ii Tuning Mirror PH PH In O TM Y E SE To A f I A MO TM PO PD MO PH MO PLMO NL PH MO TM TM 10 3 gt lt PH MBD BS 2 Beam Splitters PO BBHR PO High Reflector COMP Compensating Crystal PO BBO PO BBO Crystal HW Halfwave Plate PO PD PO Photodectector MBD 2 Mini Beam Dumps PO TM 7 PO Turning Mirrors MO BBHR MO High Reflector PO RM 2 PO Routing Mirrors MO BBO MO BBO Crystal PO PL PO Positive Lens MO PD MO Photodetector PO NL PO Negative Lens MO PL MO Positive Lens S NL Seeder Negative Lens MO NL MO Negative Lens S PL Seeder Positive Lens MO TM1 6 MO Turning Mirrors S TP1 2 Seeder Turning Prisms OC Output Coupler UV BS Ultraviolet Beam Splitter PH1_16 Pin Holes VDC4 2 Visual Dichroics Figure 5 3 The MOPO HF Beam Path and Optical Layout d The beam should pass through the UVBS without obstruction If some clipping is present make minor adjustments to IHS to center the beam onto MO
161. however the length of k varies as does k and the angle 0 to abide by the law of energy conservation As a consequence whenever 0 0 the idler will walk off the optical axis of the cavity as defined by the pump beam as the frequency is tuned In the real world the pump beam is rarely perfectly collimated and the sim ple k vector diagram is not sufficient a more complex description repre senting the converging or diverging beam is required However simply stated since the idler is a product of the pump and the signal defining the pump and signal characteristics constrains the divergence of the idler In other words a perfect system includes a collimated pump source with a collimated signal and idler whereas in the real world a typical system might include a converging pump source and a collimated signal with a Description divergent idler to compensate for the angular divergence of the pump source If on the other hand we had a diverging pump source and colli mated signal beam we would see a converging idler beam To assist in linewidth reduction the MOPO HF master oscillator uses non collinear phase matching According to the previous statements this might appear undesirable because of the idler walk off However since the idler is not used for seeding there are no deleterious consequences associated with the small amount of idler beam wander And because the signal beam is constrained by the cavity it does not exhi
162. hrough the center of ring pattern d Across section of the fringe pattern may be recorded with a digital oscilloscope e Determine the ratio of the Full Width Half Maximum FWHM of a particular fringe to the fringe spacing Figure 5 18 f The linewidth is obtained by taking the product of this ratio with the free spectral range of the etalon 2 Turn down the lamp energy and remove the pick off prism assembly 3 Turn up the lamp energy Oscillation in the MO should resume The output beam should be directed onto S TP 4 Adjust S TP so the beam propagates unclipped through BS and onto the center of S TP This completes the master oscillator alignment procedure 5 24 Installation and Alignment Peak to Peak Displacement Free Spectral Range Y Full Width At Half Maximum gt lt FWHM Figure 5 18 FWHM Ratio of a particular fringe to the fringe spacing Establish Reference Beam for Power Oscillator Note If the PO has been previously aligned establish the reference beam according to Method A below Otherwise use Method B Method A PO has been previously aligned 1 Remove PO BBHR BS S TP and the top half of the seed telescope assembly Note Use a s in hex wrench to remove the two screws holding the assembly together 2 Place a sheet polarizer in the output of the reference laser to obtain a horizontally polarized beam It is important to use horizontally polarized li
163. ility after removal There are vertical upper and horizontal lower alignment knobs for directing the beam Seeder Grating provides along with the tuning mirror a means to separate and then select a wavelength for amplification The grating splits the beam into its various component wavelengths and fans them out toward the tuning mirror The tuning mirror then reflects one of these wavelengths back to the grating The other wavelengths are reflected away from the grating and are lost The selected wavelength then becomes the seeder wavelength There are adjustments and clamping screws for holding the grating optic in place but there are no field adjustments on this device Unless the grating breaks there should be no need to replace it in the field The grating should be cleaned in place but only with puffs of dry air from a squeeze bulb Four screws fasten the mount to the base plate Do not use solvents or air from a pressurized can to clean the grating Using anything other than puffs of dry air from a squeeze bulb can cause material to become lodged in the gratings and ruin the optic Such dam aged is not covered by your warranty Tuning Mirror provides along with the grating a means to separate and then select a wavelength for amplification It selects one of the several wavelengths fanned out by the grating and reflects it back to the grating The other wavelengths are reflected away from the grating and are lo
164. illator Long Pulse Figure E 1 Placement of pick off prism for PO pump energy measure ment g h e Place the pick off prism assembly in the beam path at a location in front of the diagnostic porthole Adjust the prism to direct the beam into the power meter Set the PRO Series laser to Q SWITCH mode Record the power meter reading and determine the pulse energy Set the PRO Series laser to LONG PULSE mode Remove the pick off prism assembly Place the PO TM back onto MOPO HF E 1 Quanta Ray MOPO HF Optical Parametric Oscillator E 2 2 Choose from the following list of lens combination in accordance with the pump energy measured in Step 1j Energy Range mJ Positive Negative Lens mm fl Part Numbers 3200 150 100 1 5x 0448 8870 0448 8890 200 300 200 150 1 3x 0448 8860 0448 8880 300 350 240 200 1 2x 0451 5130 0451 5140 gt 350 550 500 1 1x 0452 2080 0452 2090 These are approximations only Depending on the Gaussian nature of the beam profile a different lens combination may be required In general more Gaussian beam profiles require less aggressive lens combinations for a given energy range e g a 1 3 x instead of a 1 5 x The opposite is true for the more flat top beam profiles Note in order to minimize beam clipping issues in the BBO crystal a Macor aperture is typically implemented with 1 1 and 1 2 x telescopes Appendix F Installing a Software Upgrade New
165. inated windows PRO Series seeder is off PRO Series seeding is unstable Master oscillator is not optimally seeding the power oscillator The crystal surface is perpendicular to the pump beam Damaged optics Damaged crystal Electronic glitch or error Loose cabling Electronics may be in MANUAL mode Electronic component failure Loose sine drive mechanism Unit out of calibration PRO Series pump beam is misaligned Master oscillator seed beam is misaligned Poor Pro series pump mode Damaged optics Damaged crystal Harmonic generator is detuned Power oscillator is misaligned Harmonic generation crystal is oriented to the wrong angle with respect to input polarization Divergence of MOPO HF output beam is not set properly Output linewidth from MOPO HF is too broad Service and Repair Symptom Cause Amplitude instability Master oscillator is not locking Master oscillator is not locking Wavelength Calibration Error appears on control box display Wavelength does not change dur ing a scan Controller display is frozen it does not change as expected Divergent mode PRO Series pump source is unstable Master oscillator seed beam is misaligned Master oscillator output power is low Master oscillator output is unstable Power oscillator crystal angel is not optimized There is excessive dither amplitude Master oscillator output power is low Master oscillato
166. iner was inspected prior to shipment it left Spectra Physics in good condition Upon receiving your system immediately inspect the outside of the ship ping containers If there is any major damage holes in the containers crushing etc insist that a representative of the carrier be present when you unpack the contents Carefully inspect your system as you unpack it If any damage is evident such as dents or scratches on the covers or broken knobs etc immediately notify the carrier and your Spectra Physics sales representative Keep the shipping containers If you file a damage claim you may need them to demonstrate that the damage occurred as a result of shipping If you need to return the system for service at a later date the specially designed container assures adequate protection System Components Accessories The following components comprise the MOPO HF system e MOPO HF laser head e MOPO HF digital controller Verify the two components are present They are shipped in separate con tainers Included with the MOPO HF system is this manual a packing slip listing all the parts shipped and an accessory kit containing the following items e US or European German power cord for the controller 2 m BNC Q SW SYNC cable for the controller e table clamp kit 4 clamps and hardware e a Bondhus SAE Allen wrench set e two alignment pinhole apertures e black pinhole aperture e infrared IR card xvii Chapter 1
167. ing the following steps By or m Use manual control see Appendix D to orient the crystal in the face normal orientation where the surface of the crystal is perpendicular to the HeNe beam then rotate the crystal until the Fresnel retroreflec tions off the BBO surface are the same distance above the MOPO HF base plate as PH Verify the reflections from the BBO crystal and compensator are in the same horizontal plane If they are not a Loosen the screw attaching the ribbon to the compensator mount b To identify the Fresnel retro reflection from the compensator man ually rotate the compensator mount while keeping the BBO mount fixed c Rotate the compensator mount until the retroreflections are in the same horizontal plane as the reflections from the BBO crystal and at the height of PH d Tighten the ribbon screw Verify the retroreflections from the BBO are directed onto the right side of the Teflon ring that surrounds the VDC optic If they are not a Loosen the BBO crystal holder b Rotate the crystal so its retroreflections are on the right side of VDC Figure 5 20 c Verify the crystal is centered in the beam and make adjustments if necessary d Tighten the crystal holder Verify the retroreflections from the compensator are directed onto the left side of the Teflon ring surrounding the VDC optic If they are not PO BBHR PO TMs PO TMg Installation and Alignment
168. ional geometrically stable cavities which provided no transverse mode control These designs were capable of delivering high output energy but with poor spatial mode quality and highly divergent beams Only the MOPO HF series geometrically unstable resonator provides high energy single transverse mode output pulses The resonator provides an output beam with a smooth Gaussian like profile minimal structure no hot spots and submilliradian divergence at all wavelengths Rear Mirror Output Coupler Figure 3 6 Schematic of an Unstable Resonator Design used in the MOPO HF Series The power oscillator is a standard two mirror linear cavity which contains the BBO crystal a broadband high reflector and an output coupler In addi tion the cavity contains two 355 nm dichroics and a crystal compensator As in the master oscillator the dichroics route the pump beam into the cav ity through the BBO crystal then out of the cavity The crystal compensa tor corrects for beam displacement which results from rotation of the BBO crystal As described in the following section the power oscillator is con figured in a manner that allows optimal seeding The signal and idler output beams from the power oscillator are overlapped as explained in Angle is Everything in OPOs below After exiting the oscillator the signal and idler are directed onto a broadband dichroic at normal incidence The dichroic transmits the idler beam whic
169. is ak a res A 3 Figure A 5 The HeNe beam retroreflections from the crystal as seen on PH for cases A and C A 4 Figure A 6 The HeNe beam retroreflections from the crystal for case B 0oo cooooooo A 5 Figure B 1 IEEE 488 Dip Switch and Jumper Settings llli B 27 Figure C 1 Three examples of PCMCIA cards 0000 cette C 1 Figure D 1 The Autotrack control pc board motor mike switches 0000 eee eee D 1 Figure E 1 Placement of pick off prism for PO pump energy measurement E 1 Figure F 1 Electronics unit showing location of removable PCMCIA memory card F 1 List of Tables Table 3 1 MOPO HF Output Characteristics lille ees 3 10 Table 3 2 Output Energy vs Pump Source 0c cee eee 3 10 Table 3 3 Tuning Characteristics liliis rn 3 10 Table 8 1 Replacement Parts e e eh men 8 5 Table B 1 IBM PC AT Serial Port Pinout a eee B 27 xii Warning Conventions The following warnings are used throughout this manual to draw your attention to situations or procedures that require extra attention They warn of hazards to your health damage to equipment sensitive procedures and exceptional circumstances All messages are set apart by a thin line above and below the text as shown here dk Danger Laser radiation is present A Laser Radiation Danger Danger Condition or action may present a hazard to personal
170. is displayed in the Operatel menu skip to the next step a From the Monitor menu press the MOPO button then use the up down buttons to select TRACK b Hold in the MOPO button until it beeps to activate the TRACK set ting Go to the desired starting wavelength a From the Operatel menu press the GOTO button then use Setting Numeric Values procedure on page 6 7 to set the GOTO wave length value b Hold in the GOTO button until it beeps to move the system to the chosen wavelength If output power does not appear optimized i e the system is not locked the L is not present on the display use MANUAL or Y DISP from the Setup2 menu to optimize output power Remember MANUAL does not save the values upon exiting that menu Operation MOPO Table Writing Procedures Please read this entire section on table writing procedure before you write a table for the first time For the MOPO HF to operate properly accurate look up tables must be implemented These tables are used to position the master and power oscil lator crystals and other MOPO HF FDO devices at angles necessary for optimal operation at every wavelength Your system was shipped from the factory with two tables a non volatile theoretical table and a factory calibrated user table that was created during system test just prior to shipment The theoretical table is provided as a backup that can be retrieved to rewrite the user table when there h
171. isposal Caution W 2 4 6 Verify when the cover interlock on the pump laser is defeated the defeat mechanism is clearly visible and prevents installation of the cover until disengaged Because the MOPO HF is not a laser and therefore cannot generate output energy without being pumped by a laser it requires no safety interlocks All safety interlocks are associated with the pump laser When the pump laser is disabled the MOPO HF is disabled Collateral radiation present While the head cover is removed and the pump laser is on be extremely careful to avoid exposure to laser or col lateral radiation When the battery in the controller is depleted please dispose of it in accordance with local laws and regulations Laser Safety CE CDRH Radiation Control Drawing Labels shown on next page i 7 Input Port ad 2 O O ks n PN MOPO HF Input End View MOPO HF Output End View 6 L SG Spectra Physics AA e Quanta Ray C3 C o USA MOPO HF Left Side View EXPORT amp Quanta Ray oooo SG Spectra Physics Ej poem el muc ER EX C MOPO HF Right Side View gt e E o SETUP
172. it is safely blocked d Change to LONG PULSE mode Use a business card to locate the 355 nm pump beam near the out put port of the PRO Series laser Danger W Avoid putting your hand or arm into the fundamental beam path 5 f Perform a vertical adjustment of IHS so that the beam is 7 5 8 in above the table surface at this point g Move the card 2 3 m away from the laser and perform a vertical adjustment of IHS so that the beam is 7 in above the table sur face at that point h Iterate adjustments of the IHS mirrors until the beam is 7 s in above the table at both locations Change to Q SWITCH OFF mode Setting up the MOPO HF 6 Place the MOPO HF in front of the PRO Series laser Figure 5 2 shows a typical table layout for this scheme If there is no internal beam dump BD place an external beam dump in front of the fundamental output port Use an IR card to ensure the PRO Series seed beam is directed into the beam dump entrance hole then securely fasten the beam dump to the table Change to LONG PULSE mode Adjust the position of the MOPO HF so the 355 nm long pulse beam is directed into the appropriate entrance hole in the MOPO HF cover then adjust the IHS mirrors in the YAG laser to align the beam with the UVBS The MOPO HF optical layout is shown in Figure 5 3 a Place a pinhole mount on the dowel pins in front of UVBS b Make minor adjustments to IHS to center the beam onto the pin
173. it is necessary to place a fluorescent white label on the flat side of the aperture Alternatively tape or glue the blank side of a business card to the aperture surface Punch a hole in the label or card at the pinhole center The pinhole must be free from material that might cause aberrations in the beam Verify the beam is propagating through UVBS without clipping In preparation for the PO alignment procedure place a pinhole aper ture on the dowel pins at PH then adjust UVBS to center the beam on the pinhole Remove the pinhole from in front of UVBS Verify the beam propa gates cleanly through UVBS without clipping and onto the center of MO TM If the beam is clipped make a horizontal adjustment of IHS 2 then re adjust UVBS as necessary to re center the beam on PH Place a beam dump in the beam path at a location between UVBS and PO TM Place MBD on the dowel pins for PH to safely block the PO pump beam during the MO alignment procedure Verify the 355 nm pulse energy in the MO optical leg is in the desired range of 60 75 mJ a Place the pick off prism in the beam path were PH would go and direct the beam out of the MOPO HF Figure 5 8 b Locate the redirected 355 nm beam with a business card and place a power meter in front of it c Adjust the pick off prism to direct the beam into the power meter d Change to Q SWITCH mode Record the power meter reading and determine the pulse energy 5 13 Qua
174. l it beeps to save the settings If either the MO or PO crystal positions are not optimized complete the rest of this procedure If they appear optimized you are done writing the threshold procedure and should continue with the Automatic Table Writ ing Procedure below 5 Set the system to table mode a From the Monitor menu press the MOPO button then use the up down buttons to scroll to TABLE Operation b Press and hold the MOPO button until it beeps to activate your selection 6 Press and hold the SET PEAK button until it beeps to re enter the peak ing routine 7 Press the CONT button to go to the wavelength s for which the system does not appear optimized and independently optimize the position of the master and power oscillator crystals a Press MO CRYS then use the up down buttons to optimize the out put of the MO b Do the same for the PO CRYS Press the CONT button to move to the next wavelength d Repeat until you are satisfied all the table points are optimized for both the MO and PO e When the SAVE button appears at the end of the procedure press it until it beeps to save these new values MOPO HF output drops when MO oscillation is terminated Alterna tively the PO may be converted to an OPA to confirm wavelength over lap refer to Chapter 5 Installation and Alignment Note g The best way to confirm you have seeded operation is to see if the 8 Set the system for a w
175. laser cover c Change to Q SWITCH mode and verify the UV energy is within 2 of the specified peak value d Set the BeamLok controller for a screen gain level of 4 for optimal adjustment sensitivity then use a 5 64 in hex wrench to adjust the pointing sensor so the horizontal and vertical bars are overlapped e Change to LONG PULSE mode f Place the cover back on the PRO Series laser g Remove the beam dump or power meter Remove the master oscillator MO and power oscillator PO half wave plates MO HP and PO HP These will be reinstalled after setup is complete Electronics and Controller Setup 5 6 Initializing the System Settings 1 2 Connect the MOPO HF to its controller 2 cables Verify the back panel line voltage switch matches your line voltage then plug the controller power cord into an appropriate outlet Attach a BNC cable between the connector on the back of the control ler box and the Q Switch output on the front of the PRO Series power supply This provides a trigger for synchronized functions within the MOPO HF controller Turn on the controller The power switch is on the back of the unit near the power cord Set the system for TABLE operation a Enter the Monitor menu Installation and Alignment Select M OSC F The border around the softkey highlights when it is selected Use the up down keys to change the lower menu item of the key to TABLE choices are TRACK and TABLE
176. ler has two sets of four switches One set controls the PO crystal the other the MO crystal Each set is identical in how it operates The following outlines the operation of one of these sets 1 Remove the cover of the MOPO HF controller and locate the Autotrack pc board then locate the control switches The control switches are shown in Figure D 1 Reference the switches from the front panel as shown in the drawing Switch designators are located near each switch PO Control Switches MO Control Switches a Control M Mike M Mike Control M Mike M Mike o selection speed direction selection speed direction 3 S Sa S S S So 9 E LI S computer manual fast slow toward blue toward red computer manual fast slow toward blue toward red 3 Push button Push button o actuator actuator REN Sa Sg Figure D 1 The Autotrack control pc board motor mike switches 2 Set S or S to the COMPUTER position move it toward you to place the crystal under computer control set it to the MANUAL position move it away from you to place it under manual control When set to MANUAL switches S4 S and S or S S4 and S are active when set to COMPUTER they are inactive Set S4 or S to the FAST position toward you to make the motormike move quickly or to the SLOW position away from you to make it move slowly for accuracy S
177. line parallel to the base plate 19 Install the PO BBHR in its standard location on the base plate The nominal separation between the OC and PO BBHR is 13 cm Adjust the PO BBHR so the retroreflections are directed onto the PH pinhole 20 Loosen the PO TMg base plate screws and rotate the mount slightly so the primary brightest retroreflection from the PO BBHR is centered on PO TM Tighten the base plate screws Caution Verify the first surface reflection from PO TM is centered onto PO TM Figure 5 22 21 Loosen the PO TM base plate screws and rotate the mount slightly so the beam is directed into the beam dump Cut a business card to an appropriate width to view the beam PO TM6 PO TM5 Compensator PO BBO xtal PO TM7 Figure 5 22 Alignment of the first surface reflection from PO TM onto PO TM Power Oscillator Overlap Procedure This procedure assumes prior alignment of the horizontally polarized refer ence beam through the PO Leave an aperture in at PH to reduce the refer ence beam size As described in the Master Oscillator Overlap Procedure the overlap procedure requires that the HeNe beam have the same vertical polarization as the pump beam This is necessary because both beams pass through a birefringent material and therefore experience a similar amount of Point ing vector walk off Because of unique geometrical constraints in the PO the overlap procedure must
178. lion shots replace the flash lamps Please note that UV performance begins to degrade at approximately 15 million shots for non BeamLok systems Operation Number of Shots as Function of Rep Rate and Duration 1 Day 8hrs 1 Week 40 hrs 1 Month 160 hrs 10 Hz 288 000 1 44 million 5 76 million 30 Hz 864 000 4 32 million 17 28 million 50 Hz 1 44 million 7 2 million 28 8 million e Monitor the environmental conditions such as temperature humidity dust and drafts on a regular basis If these conditions fall outside the recommended operating range take corrective action Identifying potential issues related to environmental conditions helps ensure optimal system performance Hints Tips amp Reminders for Daily Operation MOPO stability e For maximum stability it is very important to verify the harmonic gen erator HG in the PRO Series laser is peaked for maximum energy Verify the output is stable PO alignment e If most of the energy in the beam is off center align this portion with the pinholes as outlined in Chapter 5 Installation and Alignment e Be sure to remove BS when setting up or checking the HeNe beam alignment in the PO MOPO linewidth e Be sure the vertical adjustment on MO BBHR is adjusted for maximum output see manual for details If MO linewidth is greater than 3 modes FWHM or has gt 5 modes total increase the angle of noncollinearity between the HeNe and th
179. ller front panel RS 232 to provide a standard serial remote interface IEEE 488 a standard parallel remote interface e the parallel interface port address 1 32 e the serial interface baud rate 300 1200 2400 The Operate1 Menu Operation The Monitor1 Menu page 6 23 is displayed whenever the MONITOR button is pressed OPERATE1 M_OSC P_OSC 500000 REMOTE T 1428 1 7350 L L START MOPO SCAN TABLE It displays e the master oscillator power numerically and graphically and error tracking e the power oscillator power numerically and graphically and error tracking e the current chosen wavelength e whether the MOPO HF has been set to Track L mode or Table no designator mode The function buttons allow you to e start hold resume and abort a scan e set the MOPO HF mode to TRACK TABLE or TRK TMO track motor off Current MOPO or FDO output Select OPERATE1 menu Indicates scan progression Current Signal or Idler output 7 OPERATE PERATE1 00 000 GOTO 450 SETUP1 L 5 SETUP MONITOR1 T 1220 814nm GO TO START MOVE RECALL SAVE SCAN 0 0 MONITOR vl F Fo Fa Fa Fs S Go to Begin predeter Manually tune Recall a Save current wavelength mined scan using up down preset program under shown routine keys program numb
180. llowed by a more detailed description of the MOPO HF system The chapter concludes with system specifications and outline drawings The next few chapters describe the MOPO HF controls indicators and connections then guide you through its installation alignment and opera tion The last part of the manual covers maintenance and service and includes a replacement parts list and a list of world wide Spectra Physics service centers you can call if you need help Whereas the Maintenance section contains information you need to keep your system clean and operational on a day to day basis Service and Repair is intended to help you guide your Spectra Physics field service engineer to the source of any problems Do not attempt repairs yourself while the unit is still under warranty instead report all problems to Spectra Physics for warranty repair Should you experience any problems with any equipment purchased from Spectra Physics or you are in need of technical information or support please contact Spectra Physics as described in Customer Service This chapter contains a list of world wide Spectra Physics Service Centers you can call if you need help This product has been tested and found to conform to Directive 89 336 EEC for electromagnetic Compatibility Class A compliance was demon Quanta Ray MOPO HF Optical Parametric Oscillator strated for EN 50081 2 1993 Emissions and EN 50082 1 1992 Immu nity
181. lues originally shipped with your system 1 Before you begin the master oscillator should be well aligned and capable of oscillation see Chapter 5 Installation and Alignment Set the system to table mode a From the Monitor menu press the MOPO button then use the up down buttons to scroll to TABLE b Press and hold the MOPO button until it beeps to activate your selection Set DEVICE to MO_CRYS a From the Setup2 menu press the DEVICE button then use the up down buttons to scroll to MO_CRYS 6 29 Quanta Ray MOPO HF Optical Parametric Oscillator 4 5 b Press and hold the DEVICE button until it beeps Delete the existing tables a Press the METHOD button to select it then press it again and hold it in until it beeps b Press and hold the ABORT button until it beeps c DELETE should appear in the ABORT button box Press and hold the DELETE button until it beeps The user defined tables are deleted and the theoretical tables are loaded and become active If you have second thoughts about deleting the current user table values a quick press of the DELETE button takes you back to the ABORT button which allows you to retain the user table values Perform the Re establishing User Defined Tables procedure below Re establishing User Defined Tables 6 30 Perform this procedure after you have reloaded the theoretical table values using the previous procedure 1 8 9
182. m OPERATE1 SETUP2 MONITOR1 METHOD MANUAL It displays e Signal large and idler small output wavelength if SIGNAL is selected in the Operate 2 menu or e Idler large and signal small output wavelength if IDLER is selected in the Operate 2 menu or e MOPO HF FDO large doubled output wavelength and MOPO HF source wavelength small if FDO was selected in the Operate2 menu Refer to your MOPO HF FDO User s Manual for more information e Once a device is selected and a table writing method is chosen a sec ond menu is displayed that shows master oscillator output power PWR requested power SET and crystal position POS The function buttons provide a means to select e the device to set up MO CRYS PO CRYS OPO or FDO If FDO is selected then several devices in the MOPO HF FDO are available for display Refer to your MOPO HF FDO User s Manual for help in selecting FDO devices e the scan algorithm to be used for the selected device MANUAL Y_SHIFT LIN_INT LAGRANG LSQ_MRG MO_AUTO or PO_AUTO e the base voltage for the noise filter reference level e the peak voltage for the noise filter optimum setting The Remote Menu page 6 21 is displayed when the SETUP button is pressed two times from the Setup menu SELECT aes BAUD LOCAL 2400 NETTEN Hum MONITOR The function buttons allow you to select e the control source LOCAL to return control to the MOPO HF contro
183. minally be 5 6 mJ at 500 nm If the system does not produce 5 6 mJ of output energy a b Increase the pump energy by adjusting the HG ub plate until 5 6 mJ of MO output energy is obtained If it is still not possible to attain 5 6 mJ of MO output energy per form the following steps i Turn the system to LONG PULSE mode ii Loosen the positive lens base plate screws iii Move the positive lens approximately 1 mm away from the negative lens This adds more convergence to the beam iv Check beam collimation as described in Step 11 under Master Oscillator Overlap Procedure above Important make sure the beam is not converging i Verify the pump beam is still overlapped with the reference beam ii Attain oscillation as described above iii Measure the output energy and check the tuning range If the system still does not tune over the specified wavelength range repeat the above steps iv After the appropriate position of the positive lens is deter mined tighten the positive lens base plate screws If the desired MO output energy still cannot be attained carefully check the following i Verify the retro reflection of the HeNe at 632 816 nm is over lapped with the PH pinhole aperture ii Verify correct alignment of the HeNe reference beam refer to Establish the Reference Beam for the Master Oscillator above iii Verify the correct overlap of the pump and HeNe beams refer to Maste
184. mode It should be well collimated and showing no break up Optimize frequency overlap by adjusting the temperature potentiome ter For trained personnel only While viewing the seeded output pulse with a fast photodiode and oscilloscope adjust the seeder routing mirror for optimum pulse stabil ity For trained personnel only Quanta Ray MOPO HF Optical Parametric Oscillator Cause of Symptom Corrective Action Harmonic generator detuned Insufficient signal level on MO detector Low pump power Master oscillator is not locking Master oscillator output power is low or non existent Motor mike failed Parasitic oscillation is present Power oscillator seeding not opti mized Power oscillator high reflector PO BBHR position is not opti mized While viewing the pump power monitor optimize the second and third harmonic crystal angles Adjust the gain potentiometer on the back of the detector Remove the ND filter from the filter stack Check flash lamp lifetime If greater than 30 million shots replace lamps Note uv pump power begins to degrade after 15 million shots on non BeamLok systems Call a service representative for replacement of any damaged optics Verify MO output power is in the desired range refer to Chapter 5 Installation and Alignment Verify the beam splitter is directing the picked off portion of the beam into the detector Adjust the gain potentiometer on the
185. ms to optimize the position of the MO or PO crystal for best output power Selecting the OPO_AUTO method under F allows you to apply the same algorithm to both devices simultaneously The values obtained during the scan are saved to the user table The list of methods under F METHOD below explain the differences between the various routines MOPO HF Table Writing Procedures starting on page 6 27 explains how to select a method and write a user table Quanta Ray MOPO HF Optical Parametric Oscillator 6 18 From this menu you can also set a base and peak value for the PO PD power oscillator pyrodetector by selecting BASE or PEAK Refer to the Threshold Table Writing Procedure on page 6 31 for a description of how this works The Display Displayed are the current signal idler or MOPO HF FDO wavelengths depending on the MODE setting selected in the OPERATE2 menu The Function Keys F DEVICE MO_CRYS PO_CRYS OPO FDO selects the master oscillator MO CRYS or power oscillator PO CRYS individually or together OPO for the purpose of applying a scan algorithm to them If FDO is selected several devices in the MOPO HF FDO are available for display Refer to your MOPO HF FDO User s Manual for help in selecting FDO devices A device must be selected before you can select the table scan method you want to use under F METHOD below F METHOD XXXX selects the scan algorithm to be applied to the selected device
186. n S PL to direct the leakage light from PH 1 mm to the right of PH This eliminates potential etalon effects during a scan This completes the MOPO HF alignment procedure 5 45 Quanta Ray MOPO HF Optical Parametric Oscillator 5 46 Chapter 6 Operation MOPO HF FDO Dos and Don ts Your system must be set up on an optical table to ensure mechanical stabil ity and steps must be take to ensure there are no air currents e g heating and or air conditioning registers or ducts directly over the table and that there are no rapid changes in air temperature while the unit is running The following do s and don ts should be made part of your standard labora tory procedures for operating the MOPO HF First there is a list of things not to do followed by items that should be done By adhering to this list of procedures you will minimize the possibility of damage to your system and be assured of many hours of error free operation Don ts Do not remove a beam block from between the MOPO HF FDO and the pump laser while the laser is running Diffraction in the beam and or thermal shock to the optics can result in damage e Do not vary the PRO Series laser and or MOPO HF FDO energy with the Q SWITCH DELAY control when the flash lamps are running This can cause a significant energy redistribution in the mode Hot spots can form resulting in damage to system optics e Do not adjust the Harmonic Generator HG during th
187. n the MOPO HF controller 6 Setthe PRO Series laser to Q switch mode Verify the PRO Series laser output is within 1096 of the value it had at installation If necessary perform minor adjustments of the crystal angles in the harmonic generator to ensure output is optimized 8 Use the Monitor menu to verify the master oscillator reads within 1096 of the value it had at installation Operation 9 If the FDO is installed and you are frequency doubling change the MODE to FDO then use the Monitor menu to verify MOPO HF FDO output is within 10 of the value it had at installation 10 If you need to move the DL out of the beam path simply flip it around Loosen the screw on top then remove the entire optic mount and turn it around Place the mount so that the locating pins are reinserted and tighten the screw If the system has just been installed or reinstalled note the values from Steps 7 to 10 for future use If you have any problems following a reinstal lation refer to Chapter 5 Installation and Alignment or call your Spec tra Physics representative Daily Shut Down Procedure Follow these steps to shut your system off between periods of frequent use Instructions are given for using the analog controller on the PRO Series laser system Use the corresponding controls of the digital BeamLok con troller if it is used 1 Turn off the lamps 2 Allow the system to cool off for 5 to 10 minutes 3 Turn off the las
188. n until 1t beeps to initiate the operation The MOPO HF and FDO are automatically tuned for the proper signal idler or dou bled output wavelength desired Unlike the SCAN and MOVE commands GOTO allows movement through the degeneracy range between 345 and 366 nm although there is no output F START SCAN initiates a scan between two wavelengths Prior to per forming a scan several parameters must be programmed into the controller using the Setup menu A scan is not allowed through the degeneracy range between 345 and 366 nm F4 MOVE XX allows you to tune the output wavelength manually using the up down buttons Simply select MOVE then press the up or down button to move the system to the wavelength wanted The wavelength shown on the display is continuously updated as the system is tuned Note a MOVE is not allowed through the degeneracy range Also as you tune 1f the system needs to change from signal to idler input for the output requested or vice versa or the MOPO HF FDO needs to change the active crystal there will be a pause while the proper crystal rotates into place F RECALL 0 19 recalls previously saved parameters including the scan routine and the GOTO wavelength setting Press the RECALL button then use the up down buttons to select the set of stored parameters you wish to use 0 19 Once chosen hold the RECALL button in until it beeps to initiate the recall F5 SAVE 0 19 saves the SCAN setting
189. nal options along with diagnostic information for fast efficient control of the unit For remote control an optional RS 232 serial interface and IEEE 488 parallel interface is avail able An 8 foot cable connects the controller to the laser head Introduction The Advantage of the MOPO HF Patents e Narrow linewidth Highest damage threshold optics in the industry e Microprocessor based controller e A user friendly menu driven graphical interface e Optional IEEE 488 parallel and RS232 serial interfaces for remote control The Quanta Ray MOPO HF series is manufactured under one or more of the following patents 5 053 641 5 047 668 5 033 057 Quanta Ray MOPO HF Optical Parametric Oscillator Chapter 2 Danger Laser Radiation Laser Safety The Spectra Physics Quanta Ray MOPO HF Optical Parametric Oscil lator and its pulsed Nd YAG pump laser are a Class IV High Power Laser Products whose beams are by definition safety and fire hazards Take precautions to prevent accidental exposure to both direct and reflected beams Diffuse as well as specular beam reflections can cause severe eye or skin damage Because the 1064 nm Nd YAG output and its MOPO HF extended range of 450 to 1700 nm and the optional FDO extended range of 220 to 440 nm include harmonics that are invisible they are especially danger ous Infrared radiation passes easily through the cornea which when focussed on the retina can cause instantaneous and
190. nd increase the scan range to 480 520 nm iii Evaluate the brightness of the leakage seed light on PHg iv After the scan is complete go to the wavelength that results in maximum brightness on PHg Place the 1 in optic barrel that contains the positive lens back onto the seed telescope assembly Using 16 in hex wrench adjust the x and y position of the positive lens S PL to center the expanding beam on PH and PH Center the leakage light from PH onto PH Remove the PH and PHg apertures Adjust the distance between the positive lens and negative lenses z position adjustment to collimate the light that is coupled through the cavity Since the telescope expands the seed beam up to 6 times its ini tial size the light will overfill the clear aperture of the crystal compen sator Thus the expanded seed light will have a rectangular appearance Initial collimation is attained by making the size of the rectangular cone of light roughly the same at PH and PH Place PH and PHg back onto the base plate Verify the leakage light from PH is centered onto PH Part Il Seed beam alignment using an optical parametric amplifier OPA l 2 3 4 Change the pump laser mode to LONG PULSE Remove the PO pump beam dump from in front of the PO TM Place a power meter in the signal beam output path from the PO Insert a suitably thick hex wrench or a 10 32 screw between the ver tical adjustment push plate and
191. ns Tissue Folded for Cleaning Maintenance 3 Wipe one surface bottom to top in a single motion Be careful that the tip of the hemostat does not scratch the surface 4 Repeat this operation with a clean tissue on the second optic surface Note a clean optical surface will scatter little or no light when the laser is operating 5 Install the optical assembly back into its base and adjust the mirror vertically and horizontally for maximum optical output power This completes the optical cleaning procedure 7 3 Quanta Ray MOPO HF Optical Parametric Oscillator 7 4 Chapter 8 Danger Laser Radiation Service and Repair The Quanta Ray MOPO HF is a Class IV High Power Laser Product whose beam is by definition a safety and fire hazard Take precautions to prevent accidental exposure to both direct and reflected beams Dif fuse as well as specular beam reflections can cause severe eye or skin damage Always wear proper eye protection when working on the laser and follow the safety precautions in Chapter 2 Laser Safety Troubleshooting Guide This troubleshooting guide is for use by you the user It is provided to assist you in isolating some of the problems that might arise while using the system A complete repair procedure is beyond the scope of this man ual For information concerning the repair of your unit by Spectra Physics please call your local service representative A list of world wide servic
192. nsator mount b To identify the Fresnel retro reflection from the compensator man ually wiggle the compensator mount while keeping the BBO mount fixed c Manually rotate the compensator mount until the retroreflections are in the same horizontal plane as the reflections from the BBO crystal and at the same height as PH d Tighten the ribbon screw Manually rotate the compensator so the retroreflections from it are directed to the left side of VDC The retroreflections should also be directed onto the Teflon ring surrounding the optic Figure 5 20 f If necessary re direct the retroreflections from the BBO crystal back onto the Teflon piece Notice that the HeNe beam at PH has been displaced horizontally from the pinhole aperture To compensate for this a Re install the OC into its mount b Use a business card to identify the retroreflections from the OC and adjust the OC so the largest and brightest retroreflection is directed onto the PH pinhole aperture Note Note Installation and Alignment Improved accuracy is usually attained by directing the beam back into the laser When a correct alignment is achieved interference fringes should be noticed around the outside edge of the HeNe output aperture c Rotate the OC so the HeNe beam at PH goes onto or very close to the pinhole This can be done by loosening the retaining ring and rotating the optic holder using a small hex wrench inserted into one
193. nta Ray MOPO HF Optical Parametric Oscillator Power Oscillator ms Master Oscillat aster Oscillator MO TM Pump in SS Pick off 355 nm PHg Prism UVBS p MO TM Y To Power Meter Figure 5 8 Placement of pick off prism assembly for master oscillator pump energy measurement f If the energy is not in the desired range of 60 75 mJ choose another beam splitter see Step 2 above install it then verify the beam is still centered in PH If not centered adjust UVBS until it is g Measure the pulse energy to see if its in the desired range h Repeat this process until the required energy is obtained i To minimize the possibility of optic damage later on reduce the MO pump energy to about 60 mJ by adjusting the 2 plate on the PRO Series HG wave plate knurled knob and on the clamp This is so you can see how Note g With a pencil make a single mark at the 12 o clock position on the half far off maximum the waveplate is detuned j Change to LONG PULSE mode k Remove the pick off prism assembly 10 Establish pump beam alignment through the MO telescope a Remove the MO NL lens mount b Remove the positive lens from MO PL mount c Place pinhole apertures on the appropriate dowel pins at PH and PH 4p Note PH is a single pinhole associated with the dowel pins in front of MO TM on the double pass assembly platform d Adjust MO TM to center the beam on P
194. observed to move further apart as shown in b When the crystal is rotated clockwise the viewer observes the crystal in a direction that is parallel to the c axis In this case the lines will merge as shown in c A crystal with the c axis starting at the nearest lower corner as viewed by the observer and ending at the opposite upper corner causes the lines to merge when it is rotated counterclockwise This technique may be limited by the crystal s clear aperture and the angle of the c axis cut In general the technique is readily usable for crystals with large clear apertures and small c axis angles A 3 Quanta Ray MOPO HF Optical Parametric Oscillator Installing the Crystal in the Mount Master Oscillator 1 Place the pinhole aperture on the other side of the PH mount so that the flat side of the aperture faces the interior of the base plate This allows the reference beam retroreflections to be viewed on the flat side of the aperture during subsequent stages of the alignment proce dure 2 Insert the crystal assembly into the crystal mount i e place the BBO crystal in between the two aluminum parts 3 Turn the screw in the crystal assembly counterclockwise to spring load the assembly in the crystal mount 4 Use the manual control to rotate the crystal so that the crystal surface is approximately perpendicular to the incident reference beam Retroreflections from the surface of the crystal should b
195. of the set screws Keep the HeNe beam in the same horizontal plane as pinhole PHs 11 Install the 1 in optic PO TMg and rotate it so the HeNe is displaced to the right of the PH i e in the same horizontal plane as the pinhole See Figure 5 21 PHo Horizontal Axis Pinhole a Reference Beam Figure 5 21 Horizontal displacement of reference beam from PH pin hole 12 Install the 1 5 in optic PO TM Rotate PO TMs so the HeNe beam is directed onto the PH pinhole If you cannot direct the HeNe beam through the pinhole at least make sure it is in line with it horizontally 13 If the HeNe beam does not go through PH realign the HeNe beam through PH and PH by adjusting VDC and VDC 14 If necessary re adjust the OC so the primary retroreflection is directed back into the HeNe laser 15 Adjust the position of the BBO crystal and compensator if necessary to ensure they are centered in the HeNe beam 16 Verify the retroreflections from the BBO and the compensator hit the Teflon ring surrounding the VDC optic 17 Place the PO BBHR mount loosely on the MOPO HF base plate at a location between PH and PH and orient the mount so the back sur face faces the incident HeNe beam 5 29 Quanta Ray MOPO HF Optical Parametric Oscillator 18 Observe the retroreflections from the back surface of the PO BBHR on PH and loosen the optic and rotate it so the retroreflections are in a horizontal
196. onal RS 232 serial interface or IEEE 488 parallel interface the latter commonly referred to as the General Pur pose Interface Bus or GPIB The parallel interface is much faster than the serial interface but at the control speeds required by the MOPO HF sys tem either is acceptable Note not all systems have these optional inter faces installed If the computer interface option is included in your system a 25 pin D sub serial connector and a 34 pin Centronics parallel connector will be present in the upper right hand corner of the rear panel of the MOPO HF FDO controller This appendix describes how to install set up and use these interfaces Chapter 6 Operation The Remote Menu contains information on how to select either of these interfaces for remote control and how to return control to the controller front panel It also explains how to set the address for the IEEE 488 interface and the baud rate for the RS 232 serial inter face Two modes of control are available LOCAL or REMOTE In LOCAL mode the keys and the display on the MOPO HF controller front panel are used to enter parameters initiate operations and monitor system status In REMOTE mode a terminal or computer is used to perform the same opera tions In addition to the terminal or computer an interface cable is required to connect the command source to the MOPO HF controller Command messages are strings of ASCII characters the computer or termi nal can send
197. ong pulse beam is still going into the beam dump Change to Q SWITCH mode Take mode burns just after the negative lens and in front of the beam dump Unexposed Polaroid film works well for mode burns Place the film in a plastic bag to prevent ablated material from getting onto optical components Evaluate the relative sizes of the mode burns at the two locations The mode burn at the beam dump should be slightly larger up to about 1 mm than the one at the negative lens If the beam does not have the desired degree of beam collimation follow the procedure outlined below i Change to LONG PULSE mode ii Tape a business card to the front of the beam dump and mark the location of the beam with a pen or pencil 111 Adjust the positive lens mount position in 1 2 mm increments in the desired direction If the beam exhibits too much divergence move the positive lens away from the negative lens If the beam is converging move the positive lens toward the negative lens iv Make any necessary horizontal and or vertical adjustments to MO PL to re center the beam onto the mark on the card v Repeat this step until the desired degree of collimation is attained 12 Establish a 2 non collinear alignment of the pump in the MO a Locate the first surface reflection of the HeNe beam from MO TMs Two HeNe beam reflections should be noticed from the mirror The first surface reflection is the one which appears closest to the B
198. or output power in rel ative terms of 0 to 100 of full power The bar graph to its right shows the tracking error signal This bar is ideally at the center of the graph i e in its balanced position of minimum error signal The number indicates a relative setting of the crystal angle An L denotes track mode is selected To the right of these bar graphs is another set of bar graphs that indicate the output power and tracking error signal for the power oscillator The number in the upper right hand corner is the wavelength of the mode device selected from the Operate2 menu SIGNAL IDLER or FDO The Function Keys F N A F2 START SCAN allows you to start a scan then stop it HOLD resume it or abort it F4 N A F4 MOPO TRACK TABLE TRK TMO selects the MOPO HF operating mode TRACK TABLE and TRK TMO track with motor off The latter turns off the motor to reduce noise Fs N A 6 23 Quanta Ray MOPO HF Optical Parametric Oscillator Switching Between MOPO and FDO Operation Switching from MOPO to FDO Operation 1 Set system mode to FDO a From the Servicel menu press the MODE button then use the up down buttons to select FDO b Press the MODE button until it beeps to activate this selection Set the PRO Series controller to Q SWITCH OFF Install the MOPO HF FDO TP turning prism in its normal non parked position The prism is fastened to the mounting plate by two 10 32 lock down screws
199. outside the cavity near PO TM Use a business card cut to a 15 20 mm width to locate the beams Make sure the first surface reflection of the HeNe beam from PO TM is used Figure 5 23 Note Due to walk off effects it is important not to overlap the beams in between the crystal and PO TM g Adjust PO TM to overlap pump and HeNe laser beams at a loca tion in front of the beam dump 5 33 Quanta Ray MOPO HF Optical Parametric Oscillator 5 34 h Reiterate Steps f and g until the beams are overlapped in the two locations Note If it is difficult to attain overlap by iterating these adjustments e g run out of travel on one of the mounts perform the following steps 11 12 13 14 Ix i Reset PO TM and PO TM adjustments to the middle of their ranges ii Loosen the PO TM base plate screws Note that PO TM is on a sliding base iii Reposition PO TM in an arbitrary direction along the sliding base iv Rotate PO TM until the pump and HeNe beams are relatively well overlapped near PO TMg v Note the displacement of the two beams near the pick off prism vi Re iterate Steps iii v until the beams are relatively well over lapped in the two locations Note if the displacement of the beams appears to be getting larger at the pick off prism reposi tion PO TM in the opposite direction along the sliding base Tape a business card over the PO pump diagnostic output port Con firm th
200. p PRINT TotalLoops TotalLoops PRIND Wasesa anaa T PRINT Parameter Sent Received PRIND Wasana an aja T PRINT Begin ScanBegin Responsel PRINT End ScanEnd Response2 PRINT Increment Increment Response6 PRINT Shots Shots Response4 PRINT Scans scans Response5 PRINT IF faultflag 1 THEN PRINT Incremental Scan Setup ERROR PRINT Program Terminated END multiloop multiloopmax INCREMENTAL SCAN PRINT 1 scan PRINT Incremental scan running PRIN type Incr GOSUB WaitForScan n B 13 Quanta Ray MOPO HF Optical Parametric Oscillator PRINT PRINT PRINT PRINT PRINT GOSUB Saving parameter setup TotalLoops total loops 1 save 3 Save current operating parameters into non volatile memory as setup record 43 Recalling parameter setup TotalLoops total loops 1 recall 4 Load setup parameters record 4 from non volatile memory WaitFiveSeconds NEXT multiloop GOTO TotalLoop makes an infinite loop program PRINT End of Sample Program END End of Sample Program READ SETUP SUBROUTINE ReadSetup PRINT Verifying setup PRINT PRINT 1 source begin GOSUB readdata Responsel VAL responseS PRINT GOSUB 1 source end
201. p beam alignment 0 000e eee o 5 16 Figure 5 10 Placement of Pick off Prism for Pump Collimation 00000020 e eee 5 16 Figure 5 11 Overlap Location of HeNe Reference and Pump Beams iussus 5 18 Figure 5 12 Overlap location for master oscillator overlap procedure 00000eeeee 5 18 Figure 5 13 Retroretlection from MO TMp a A CR atc 5 20 Figure 5 14 Placement for pick off prism assembly for master oscillator output energy measurements CL 5 20 Figure 5 15 A business card folded and hung over the MO BBHR 20 20 e0e05 5 21 Figure 5 16 Retroreflections from the MO BBHR shown in the correct horizontal orientation 5 21 Figure 5 17 Airy Diffraction pattern by narrow linewidth radiation passing through a high firiesse etalot 1 orm doe e Rede Seb Eg Re Suc Mb Fusce pb x RUD ATE UR M ROS RE RUNE qs 5 24 Figure 5 18 FWHM Ratio of a particular fringe to the fringe spacing ooooooooooooo 5 25 Figure 5 19 Reference beam alignment for the power oscillator For clarity some components ALE MO ESA WA secrete keep bd cemere BE a E dare e Eton M e nte di ice 5 25 xi Quanta Ray MOPO HF Optical Parametric Oscillator Figure 5 20 Orientation of the BBO Crystal aa a ren 5 27 Figure 5 21 Horizontal displacement of reference beam from PH pinhole 5 29 Figure 5 22 Alignment of the first surface reflection from PO TMg onto
202. pRu rH UJ UJ 081 20 6 Front View Side View MOPO HF Digital Controller Figure 3 11 Outline Drawings 3 12 All dimensions in inches mm Chapter 4 Controls Indicators and Connections Introduction This section defines the user controls indicators and connections of the MOPO HF system It is divided into two sections the MOPO HF head and the MOPO HF control module Figure 4 1 shows the relative position of the various components in the MOPO HF MBD PO TM y PO TM xX PH TE J 1 gt PH PO L PO NL PH PO TM Z Y y PO TM PH DK a T OC BS PH VDC AM STe PO BBO COMP X Q4 eg M U gt F f gt Idler Beam Out PH SNL S PL PO PO TM PO TM 7 Lx signal Beam Out HW T BS BBHR AL c T 1 VBC PH MO PD 6 PH MO TM MO TM MO BBHR Y PH A luves 5 NJ x Sip ee tee E x UV 355 nm y N E es Pump Beam X AN m 13 In PH O TM 1 A MO TM PO PD MO PH MO PLMO NL PH MO TM TM gt lt PHig MBD BS 2 Beam Splitters PO BBHR PO High Reflector COM Compensating Crystal PO BBO PO BBO Crystal HW Halfwave Plate PO PD PO Photodectector MBD 2 Mini Beam Dumps PO TM4 7 PO Turning Mirrors MO BBHR MO High Reflector PO RM 2 PO Routing Mirrors MO BBO MO BBO Crystal PO PL PO Positive Lens MO PD MO Photodetector PO NL PO Negative Lens MO PL MO Positive Lens S NL Seeder Negative Lens MO NL
203. permanent damage Precautions For The Safe Operation Of Class IV High Power Lasers Eyewear E Required a Wear protective eyewear at all times selection depends on the wave length and intensity of the radiation the conditions of use and the visual function required Protective eyewear is available from suppliers listed in the Laser Focus World Lasers and Optronics and Photonics Spectra buyer s guides Consult the ANSI and ACGIH standards listed at the end of this section for guidance To avoid unnecessary radiation exposure keep the protective cover on the laser head at all times Avoid looking at the output beam even diffuse reflections are hazard ous Avoid blocking the output beam or its reflections with any part of the body Avoid wearing reflective jewelry while using the laser Use an infrared detector or energy detector to verify the laser beam is off before working in front of the laser Operate the laser at the lowest beam intensity possible given the requirements of the application Operate in the long pulse mode whenever possible especially during alignment of the experiment Expand the beam whenever possible to reduce beam intensity 2 1 Quanta Ray MOPO HF Optical Parametric Oscillator Caution W 2 2 e Establish a controlled access area for laser operation Limit access to those trained in the principles of laser safety e Set up experiments so the laser beam is either above or
204. perture assemblies on the dowel pins at PH and PH Adjust VDC to center the beam on PH 5 27 Quanta Ray MOPO HF Optical Parametric Oscillator 5 28 10 g Adjust VDC to center the beam on PH h Iterate the last two steps until the beam is centered through the two pinholes Reverse the pinhole in PH so the flat side faces the BBO crystal This allows retroreflections from the oscillator optics to be seen during the following steps Install the BBO crystal and compensator a Install the BBO crystal in its holder as described in Appendix A b Position the BBO so it is flush with the outside edge of the mount Use manual control see Appendix D to orient the crystal in the face normal orientation where the surface of the crystal is perpendicular to the HeNe beam then rotate the crystal until the Fresnel retroreflec tions off the BBO surface are the same distance above the MOPO HF base plate as PH Adjust the BBO crystal so the retroreflections from its surfaces are directed onto the right side of the Teflon ring that surrounds the VDC optic Figure 5 20 Install the compensator in its holder using the same technique used for the BBO crystal again refer to Appendix A Position the compensa tor so that it is flush with the outside edge of the mount Adjust the compensator so its face is also in a face normal geometry with respect to its front surface a Loosen the screw attaching the ribbon to the compe
205. phase spectroscopies The tuning and energy range of the MOPO HF have not been compro mised in the effort to narrow the linewidth Tuning with a single optics set still exceeds 450 1700 nm and some systems have output energy levels in excess of 75 mJ Optimum performance is achieved when the MOPO HF is pumped with a Quanta Ray BeamLok PRO series 230 or 250 10 Hz pump laser due to its enhanced alignment and power stability The patented Spectra Physics MOPO FDO 970 frequency doubler extends the output to include the uv from 225 to 445 nm This doubling option fits inside the MOPO series for ultimate integrity and long term alignment The MOPO HF system includes the oscillator head the digital controller and optionally the MOPO FDO 970 frequency doubler Chapter 3 contains a complete description of the MOPO HF system The OPO head contains all the mechanical and optical components neces sary to generate laser light It houses the master oscillator and power oscil lator ergo MOPO and it uses a Type I beta barium borate BBO crystal as its nonlinear parametric gain medium The MOPO Digital Controller 1 2 Figure 1 2 The Quanta Ray MOPO HF Digital Controller The digital controller contains a simple menu driven control program that uses soft keys and clear large characters on a back lit display to provide an easy method of controlling and monitoring the system The intuitive layered menu structure provides operatio
206. pproximately 2 3 m from the idler output port Change to Q SWITCH mode Oscillation in the PO should be observed Allow a several minute warm up period The oscillating wavelength may be somewhat different than 500 nm The actual wavelength is determined by a default look up table value in the MOPO operating system The operating wavelength will be set to 500 nm when seeding is achieved Once the output from the PO has stabilized place an IR card behind VDC The idler should be visible along with some leakage from the signal beam Make adjustments to the beam dump to ensure the beam is safely blocked When viewing the idler tilt the card downward to minimize the chance of directing the scattered light back toward the viewer 9 Assess the relative positions of the signal and idler If the signal and idler beams are displaced from one another adjust the vertical on PO TM to overlap them If there is a horizontal displacement of the beams a horizontal adjust ment of PO TM is necessary Set to LONG PULSE mode to avoid expo sure to the beam Make the adjustment Turn back to Q SWITCH mode and assess the signal and idler overlap Repeat until overlap is achieved Suggestions for viewing the signal idler overlap e Use a visible cut off IR pass filter in the beam path to view the rel ative positions of the two beams e If available place a 1 2 m positive lens in the idler beam path View the signal an
207. r Oscillator Overlap Procedure above 6 Verify the MO can be tuned over its specified operating wavelength range a Goto 450 nm b Usethe manual crystal control see Appendix D to rotate the crys tal until oscillation is observed Go to 690 nm and repeat this procedure to verify oscillation can be achieved at this wavelength as well 5 23 Quanta Ray MOPO HF Optical Parametric Oscillator Note For optimal operation the energies at the extremes of the tuning range should be 1 2 mJ Note Beware of multiple oscillations near 690 nm These additional oscilla tions are at wavelengths that are shorter than the primary order The cor rect order may be identified as being the last one observed as the crystal is tuned to the red Linewidth Measurement 1 Verify the time averaged linewidth e g 50 shot average at the FWHM is no more than three modes at 500 nm One to two modes at FWHM is typical a Direct the MO output through a 0 25 cm Fabry Perot Analyzer FPA b A concentric ring or Airy diffraction pattern should be visible Figure 5 17 Slit Card Target Screen Airy Ring Diffraction Pattern Ay A Input Beam from MOPO H FPA h Front View of Target Screen Figure 5 17 Airy Diffraction pattern by narrow linewidth radiation passing through a high finesse etalon c Place a linear diode array in the focal length plane of the FPA The diode array should go t
208. r is not operating Insufficient signal level on the MO detector Unit is in INT mode instead of EXT mode M mike is in TABLE mode instead of TRACK mode Controller is in HOLD mode Electronics glitch or software error Loose cabling An electronic component failed Mechanical looseness in the sine drive mechanism Linear potentiometer is displaced greater than Y in from an integral number of turns from the sine bar reference point Controller is in MANUAL mode Motor mike has failed Electronics glitch or error Parasitic oscillation is present in master oscillator Q switch trigger is absent Electronics error occurred Power oscillator high reflector PO BBHR position is not optimized Parasitic oscillation is present Part 2 Cause of Symptom Corrective Action Damage crystal and or optics Electronics glitch or error Electronic component failed PRO Series pump beam is mis aligned PRO Series seeding is unstable Replace the damaged crystal or optic and realign the system as described in Chapter 5 Installation and Alignment Turn off the MOPO HF controller wait three seconds then turn it back on Identify the failed component and replace it or send the controller back to the factory for repair Re align the pump beam as described in Chapter 5 Installation and Alignment Verify the seeder is set to AUTO mode With the PRO Series in EXT mode check the seeder
209. re 5 12 The following procedure assumes prior alignment of the reference beam through the MO Leave the pinhole aperture in PH to reduce the reference beam size The first two steps below determine which beam splitter UVBS is required Perform these steps only if the MOPO HF has not been previ ously aligned If previously aligned and UVBS is already installed skip to Step 5 1 Measure the 355 nm output power from the PRO Series pump laser a Turn on the PRO Series laser to LONG PULSE mode b Locate the 355 nm beam with a business card at the output of the PRO Series laser c Placea suitable power meter in the beam path Change to Q SWITCH mode Record the power meter reading and determine the pulse energy Note Installation and Alignment Choose a beam splitter from the table below that will yield transmitted pulse energies in the range 65 75 mJ values are given in Transmis sion 0451 1170 12 0451 6440 14 0449 1100 17 0451 0670 20 0449 1110 24 The formula for calculating transmitted energy is transmitted energy pump energy x transmission of beam splitter 100 Example Given 500 mJ of 355 nm output a 14 beam splitter yields the following transmission value 500 mJ x 14 100 70 mJ Change to LONG PULSE mode Install the chosen beam splitter in UVBS Be careful not to touch the optical surfaces In order to view the 355 nm LONG PULSE beam on an aperture in the subsequent steps
210. releases of the MOPO HF controller software might be issued that will upgrade your system to add new capabilities or increase its perfor mance If this occurs use the following procedure to install the new soft ware This procedure is simple and straight forward but it must be followed precisely to prevent any loss of any data already stored in your unit You will swap your current PCMCIA card in the controller with a new one and will have to do this a couple of times If the two cards are from the same manufacturer it may be prudent to mark the old one to identify it so that you do not inadvertently insert the wrong card If this happens you will lose your original data 1 Verify the MOPO HF controller is off 2 Remove the cover from the controller 3 Remove the old PCMCIA card It is plugged into the mother board just behind the front panel see Fig ure F 1 Pull it straight up and out 4 Carefully insert the new PCMCIA card making sure the rectangular notch at the base of the card is to the right as viewed from the front of the controller the illustration shows the card as viewed from the rear of the controller Memory Card Front Panel Figure F 1 Electronics unit showing location of removable PCMCIA memory card F 1 Quanta Ray MOPO HF Optical Parametric Oscillator F 2 10 11 12 Turn on the controller The new software will boot Once the opening menu is displayed press the OPERATE button until
211. ring process Neverthe less even the finest precision instruments will need occasional service We feel our instruments have excellent service records compared to competi tive products and we hope to demonstrate in the long run that we provide excellent service to our customers in two ways first by providing the best equipment for the money and second by offering service facilities that get your instrument repaired and back to you as soon as possible Spectra Physics maintains major service centers in the United States Europe and Japan Additionally there are field service offices in major United States cities When calling for service inside the United States dial our toll free number 1 800 456 2552 To phone for service in other coun tries refer to the Service Centers listing located at the end of this section Order replacement parts directly from Spectra Physics For ordering or shipping instructions or for assistance of any kind contact your nearest sales office or service center You will need your instrument model and serial numbers available when you call Service data or shipping instruc tions will be promptly supplied To order optional items or other system components or for general sales assistance dial 1 800 SPL LASER in the United States or 1 650 961 2550 from anywhere else This warranty supplements the warranty contained in the specific sales order In the event of a conflict between documents th
212. s In most cases the chosen method will be used to create a user table to be used as a reference source The following describes each of the seven available selections MANUAL allows you do perform what if trials You can manipulate the chosen DEVICE manually to see what happens Once this method is chosen a second menu appears with an ADJUST but ton Press the ADJUST button then use the up down buttons to move the device and watch the results on the bar graph on screen When you are done press the CONTinue button to return to normal operation The current setting will not be saved and the device will return to its previous position Y SHIFT allows you to use the ADJUST button and the up down buttons to shift up or down the entire data table associated with the selected device This shift constitutes a single value point yet the entire table is shifted by the same amount over the entire turning curve This method is useful when you find something has shifted an optic has moved slightly and that a simple shift of all the points in the user table by a single value returns the system to optimal performance LIN INT performs a linear interpolation to find idealized theoretical values over a prescribed scan range set up under the Setupl menu The beginning scan wavelength must be less than the ending wavelength and with regard to the MOPO HF FDO the wavelengths must be appropriate for the selected device This algorithm allows
213. s a group all reference points will be lost making realignment extremely difficult Work in a clean environment over an area covered by a soft cloth or pad Wash your hands thoroughly with liquid detergent and use finger cots when handling optics Body oils and contaminants can render otherwise fastidious cleaning practices useless Use dry nitrogen or a rubber squeeze bulb to blow dust or lint from the optic surface before cleaning it with solvent Permanent dam age may occur if dust scratches the glass or coating Use spectroscope or electronic grade solvents Do not try to remove contamination with a cleaning solvent that may leave other impurities behind Use photographic lens tissue to clean optics Use each piece only once a dirty tissue merely redistributes contamination Cleaning Optical Components Warning W Do not clean the crystals or the grating with solvent This will damage them Only use air Damage caused by cleaning is not covered by your warranty Equipment Required Dry nitrogen or rubber squeeze bulb Photographic lens tissue Spectroscopic or electronic grade methanol Forceps Hemostat Cleaning Prisms and Mirrors 1 Blow away dust particles or lint using nitrogen or air 2 Fold a piece of lens tissue into a pad about 1 cm on a side and clamp it in a hemostat see Figure 7 1 Saturate the pad with methanol shake off the excess resaturate and shake again SS SS Figure 7 1 Le
214. s and the GOTO wavelength set ting Press the SAVE button then use the up down buttons to select the set number 0 19 under which you wish to store the present parameters Once chosen hold the SAVE button in until it beeps to initiate the save Operation The Operate2 Menu Select OPERATE2 menu Current MOPO or FDO output 7 OPERATE a PERATE2 SETUP1 500 000 SL MONITOR1 1220 814nm XA MODE MODE UNITS M OSC P OSC SIGNAL NORM nm 1 1 MONITOR 1 F4 Fo F3 Fa Fs A Set display to Set MOPO mode Set MOPO units Set MO Set PO SIGNAL IDLER to NORM to nm or cm display gain display gain or FDO or MICRO Figure 6 3 The Operate2 Menu The Operate2 menu appears when the OPERATE button is pressed once from the Operatel menu This menu allows you to select the wavelength display format set the display to normal 6 digits or micro 7 digits the wavelength display format nm or cm and to independently set the dis play gain for the master and power oscillators 1 e it increases the sensitiv ity of the bar graphs it does not increase actual oscillator gain The latter also amplifies the movement of the bar graphs in the Monitorl menu Sometimes a higher display gain can be helpful such as when calibrating the oscillator at a low power wavelength Lower resolutions are useful in most case
215. s in off the optical table Polarizing material e g Edmund Scientific sheet polarizer P N 71942 Potentiometer adjustment tool 0 25 cm Fabry Perot etalon e g Spectra Physics P N 0100 8270 Power meter Setting up the PRO Series Laser 1 Place the PRO Series YAG laser in an appropriate location on the opti cal table and clamp the feet to the table Figure 5 2 shows a typical table layout for a PRO Series laser and MOPO HF The MOPO HF may also be placed on the table but do not place it in front of the PRO Series laser at this time Provided with system Installation and Alignment Note Set up the PRO Series YAG laser in accordance to its user s manual This should be done by a qualified individual only i e someone who has received appropriate training IHS 355 nm MOPO HF PRO Series Laser gt HG m IHS 1064 532 nm Residual Beam Beam Dump Figure 5 2 Typical Table Layout for a PRO Series Pump Laser and the MOPO HF laser before you begin aligning the MOPO HF Caution W Verify the alignment mode and seeding characteristics of the pump 2 Turn on the PRO Series laser and allow it to warm up a little The spatial mode of the 355 nm output at 3 m should be uniform with no significant hot spots localized regions of high intensity 3 Set the PRO Series fundamental beam height to 19 37 cm 7 63 in above and parallel to the table surfac
216. s when simply monitoring system output and you want to see peak values Available gain settings are 1 2 4 8 or 16x This feature is saved along with all other data when using the SAVE function from the Operatel menu The Display When SIGNAL has been selected the large number in the upper right hand box is the signal wavelength and the idler is the small number If IDLER is selected these numbers are reversed If FDO is selected the large number is the MOPO HF FDO doubled wavelength and the small one is the signal Under normal conditions set the display to NORM There are times how ever when more accuracy is required In these cases set the system to MICRO to display a 7th digit of accuracy For your convenience you can have the display read wavelengths in nanometers nm or wavelength numbers cm The bar graph display gain can be set to 1 2 4 8 or 16x so that it is appro priate for the task The current gain value for the MO and PO is displayed in the F and F button windows A higher gain can be helpful for example when calibrating the oscillators at a low power wavelength Lower resolu 6 13 Quanta Ray MOPO HF Optical Parametric Oscillator The Service1 Menu 6 14 tions are useful in most cases when simply monitoring system output This feature is saved along with all other data when using the SAVE function from the Operatel menu The Function Keys F MODE SIGNAL IDLER FDO allows you to select th
217. scillator 10 11 12 13 14 15 16 This allows internal controller operation during the following steps without the need to run the PRO Series laser To operate the MO and PO monitors the trigger must be changed back to the Q SWITCH out put port which will be done at a later step If the crystal is not installed skip to Step 11 otherwise a Use manual control see Appendix D to orient the crystal in the face normal orientation surface of the crystal is perpendicular to the HeNe beam b Verify the retroreflections off the face of the crystal are on the back side of PH 4 The beams should be in one of the two locations described in Appendix A i e the closest retro reflection to the pinhole should be either 10 mm to the left or 20 mm displaced to the right c If the retroreflections are not in one of the two orientations described above take the crystal out and re install it using the pro cedure described in Appendix A If the BBO crystal is not installed install it now See Appendix A Installing the BBO Crystal Remove S TP This allows the HeNe beam to pass onto PH Using the MOPO HF controller go to the wavelength of the reference beam 632 816 nm for a HeNe laser a Access the Operate menu and enter 632 816 nm in the GOTO key b Press the GOTO button down and hold it until a beep is heard The reference beam should travel through the middle of the crystal and intercept the cen
218. segu zichtbare laserstral 6 Cas D Ouverture et Laserstrahlung wenn ridad exist radiaci n ing wanneer geopend lorsque la securite Abdeckung geoffnet laser visible e invisi en bij uitgeschakelde est neutralisee expo und Sicherhetisschal ble evite que los ojos interlock Vermijd sition dangereuse de ter uberbruckt O la piel queden blootstelling van oog l oeil ou de la peauau Bestrahlung von expuestos tanto a la of huid aan directe rayonnement direct Auge oder Haute radiaci n directa straling of weer ou diffus Puissance durch direkte oder como a la dispersa kaatsingen daarvan et longueurs D onde Streustrahlung ver Potencia Longitud de Vermogen dependant de la con meiden Leistung onda y anchura de golfleugten en pulsd figuration et de la Wellenlange und pulso dependen de uur afhankelijk van puissance de pompe Pulsbreite sind las opciones de pomp optics en laser Laser de Classe 4 abhangig von bombeo y de la con configuratie Klasse 4 Pumpquelle und figuracion del laser Laser Produkt Laserkonfiguration Producto laser clase Laserklasse 4 4 Patent Ce produits est fab Dieses Produkt Este producto esta Dit product is gefabri Label riqu sous Tun ou wurde unter Verwen fabricado con una o ceerd met een of 9 plusieurs des brevets dung einer oder m s de las siguientes meer van de vol suivants mehrerer der fol patentes de los Esta gende USA patenten genden US Patente dos Unidos hergestellt Battery Remplacer la pile par B
219. st The selected wavelength then becomes the seeder wavelength There are adjust ments and clamping screws for holding the mirror in place but there are no field adjustments on this device Unless the mirror breaks there should be no need to replace it in the field The mirror should be cleaned in place but only with puffs of dry air from a squeeze bulb Four screws fasten the mount to the base plate Do not use solvents or air from a pressurized can to clean the tuning mirror Using anything other than puffs of dry air from a squeeze bulb can ruin the optic Such damaged is not covered by your warranty S TP seeder turning prism directs the beam through BS and on to S TP It has a backing flag to prevent any stray light from getting past the prism Two screws can be loosened for vertical adjustment and 2 screws fasten the mount to the base plate Controls Indicators and Connections BS beam splitter directs part of the beam to the master oscillator photo detector which monitors master oscillator output Two screws fasten the mount to the base plate S TP turning prism directs the beam from S TP and on to the seed telescope see below It has a backing flag to prevent any stray light from getting past the prism Two screws can be loosened for vertical adjustment and 2 screws fasten the mount to the base plate Seeder Telescope contains the seeder positive and negative lenses S PL and S NL for changin
220. stem is in track mode then select a device for which you want to write a set of user table values then select the table writing method you want to use Although counter intuitive selecting track mode instead of table mode when writing a table allows the system to automatically peak track performance for each value point 1 Set the system to track mode a From the Monitor menu press the MOPO button then use the up down buttons to scroll to TRACK b Press and hold the MOPO button until it beeps to activate your selection 2 Select the device for which you will write a table a From the Setup2 menu press the DEVICE button then use the up down buttons to scroll to the desired device Note If the FDO is present several MOPO HF FDO devices will also be available from which to choose Refer to your MOPO HF FDO User s Manual for help in selecting FDO devices b Press and hold in the DEVICE button until it beeps to activate your selection 3 Select a table writing method a Press the METHOD button then use the up down buttons to scroll to the method you want to use Refer to the descriptions of table writ ing methods that start on page 6 18 b Press and hold the METHOD button until it beeps to activate this selection When the METHOD button beeps the menu shown below is displayed and the table writing routine begins Displayed are MO and PO output power PWR requested power SET and crystal position POS
221. t Laser sichtbarer un unsicht rar el dispositivo de neit zichtbare lasers type Visible et Invisible en barer Laserstrahlung seguridad exist radi traling wanneer Danger Cas D Ouverture et wenn Abdeckung aci n laser visible e geopend en bij uitge Label lorsque la securite geoffnet und Sicher invisible evite que los schakelde interlock 5 est neutralisee expo sition dangereuse de l oeil ou de la peau au rayonnement direct ou diffus Puissance et longueurs D onde dependant de la con figuration et de la puissance de pompe Laser de Classe 4 hetisschalter uber bruckt Bestrahlung von Auge oder Haute durch direkte oder Streustrahlung ver meiden Leistung Wellenlange und Pulsbreite sind abhangig von Pumpquelle und Laserkonfiguration Laserklasse 4 ojos o la piel queden expuestos tanto a la radiaci n directa como a la dispersa Potencia Longitud de onda y anchura de pulso dependen de las opciones de bombeo y de la con figuracion del laser Producto laser clase 4 Vermijd blootstelling van oog of huid aan directe straling of weerkaatsingen daar van Vermogen golfleugten en pulsd uur afhankelijk van pomp optics en laser configuratie Klasse 4 Laser Produkt Quanta Ray MOPO HF Optical Parametric Oscillator Label French German Spanish Dutch CE Dan Rayonnement Laser Austrittvonsichtbarer Al abrir y retirar el Zichtbare en neit ger Label Visible et Invisible en un unsichtbarer dispositivo de
222. t so that the MOPO HF FDO can be controlled by a serial device such as a terminal or a personal com puter configured as a terminal or an IEEE 488 control source Once set this becomes the default control source until changed again by you Appendix B Using the RS 232 IEEE 488 Interface provides a complete description of these interfaces and their command structure and explains how to use them Several software examples are also provided Caution When activating the selection during the following procedures if the function button is not held in until the beep the unit will revert back to its previous setting when you leave this menu Control Source Selection To select the control source 1 Press F to begin the selection process 2 Use the up down buttons to toggle to the desired device RS 232 IEEE 488 or LOCAL 3 Press F and hold it in until it beeps to activate the chosen control source When one of the optional interfaces is selected as the control source the Operator menu is displayed and LOCAL is displayed over F Pressing F returns the system to local operation Figure 6 8 IEEE 488 Address Selection The default address for the IEEE 488 interface is 15 but it can be changed to any address from 0 to 31 To change it 6 21 Quanta Ray MOPO HF Optical Parametric Oscillator 6 22 Current MOPO or FDO output Current Signal or Idler output
223. t than that in a laser In a laser gain is derived from energy stored in the excited states of an atomic or molecular transition The source of this excitation energy may be radiative thermal or electrical Once energy is stored in an excited state it may be extracted through the process of stimulated emission in an appropriately configured optical reso nator In this process photons are initially produced by spontaneous emis sion from the laser transition The photons that are directed along the optical axis of the resonator force stimulate the emission of photons from other excited atoms or molecules encountered in the gain medium These photons have the same frequency phase and directional character of the primary photon Multiple passes through the gain medium results in a geo metrical increase in the number of photons in the cavity Oscillation thresh old is reached when the number of photons generated gain equals the number lost in one round trip The source of gain in an optical parametric oscillator is physically distinct It is this difference that underscores the dissimilarity between lasers and Quanta Ray MOPO HF Optical Parametric Oscillator 3 8 OPOs as commercial devices As discussed previously gain in an OPO is derived from a nonlinear optical phenomenon which results in the decom position of a pump photon into a signal and idler photon Unlike a laser this process does not require a real atomic or molecular transi
224. table for the master oscillator MO crystal you would first select the MO crystal as the device upon which to be operated from the Setup2 menu which is covered later in this chapter then select Y_DISP as the method To do this press the DEVICE button F to highlight it Next use the up down keys to scroll to MO CRYS Finally press the DEVICE button again and hold it in until it beeps to set the master oscillator crystal as the selected device In the same manner use the SSS process to select the Y SHIFT function press the METHOD button Fo to select it then use the up down buttons to scroll to the Y SHIFT function then set it by holding the METHOD button in until it beeps The MO CRYS and the Y SHIFT function will remain the active selections until you manually change it Note that although many procedures for the MOPO HF FDO use the SSS process not all require it See Setting Numeric Values below Operation Setting Numeric Values The SSS procedure is not used with the Setup menu to set numeric values Instead press the function button whose value you want to change then press that same button repeatedly to select the digit you wish to change an underscore symbol moves under the digits and use the up down buttons to change the numerical value of that digit Press the function button again to move to the next digit etc the underscore rotates from left to right with each press Do not press and hold the button to set
225. tical or horizontal adjustments for directing the beam MO TM master oscillator turning mirror routes the beam from the tele scope to turning mirror MO TM A white flag on the top of this mirror captures and absorbs any stray reflections resulting from the rotation of the crystal Although the mirror can be cleaned in place it can be removed by removing 3 screws of the retaining ring with an Allen ball driver and removing the mirror along with the retaining ring The optic is flat so there is no set orientation and it is spring loaded against 3 balls for repeatable seating There are vertical lower and horizontal upper alignment knobs for directing the beam MO TM master oscillator turning mirror routes the beam from MO TM to the BBO crystal Although the mirror can be cleaned in place it can be removed by using an Allen ball driver to loosen the 3 D cams that hold it in place then turning the cams to release the mirror The optic is wedged so there is a set orientation but there are no markings on the mirror for orien tation Orientation is set during the alignment procedure It is spring loaded against 3 balls for repeatable seating There are vertical lower and hori zontal upper alignment knobs for directing the beam MO BBO crystal master oscilltor crystal is the nonlinear wavelength tuning element A single screw holds it in its holder and the holding arm rotates the crystal via a motor driven by the MOPO
226. tion Thus there is no energy storage capability Useful gain in an OPO is derived by appropriate phase matching in a birefringent crystal This occurs at a unique angle formed by the direction the pump wave defined by its corre sponding wave or k vector and the optic axis of the crystal Thus in a critically phase matched OPO such as the MOPO preservation of this angle is crucial for maintaining appropriate performance Figure 3 9 shows two wave or k vector diagrams that are geometric des criptions of the law of conservation of momentum Figure 3 9a represents the collinear phase matching process The pump wave k is converted to the signal wave k and the idler wave k If the resonated signal wave is collinear with the pump beam and the pump beam is overlapped with the resonator axis the idler must also be collinear in order to satisfy the equa tion k k k The idler is always the longest wavelength or shortest wave vector Note k and k are actually overlapped but are offset in the illustration for clarity ki ki ki k Kp Kp kp i Ks D ks ks a b Figure 3 9 Collinear a and noncollinear b phase matching Figure 3 9b is wave vector diagram that describes the phase matching of the three beam components when the signal beam is not collinear with the pump beam but is aligned at an angle with respect to the pump beam When this is the case angle remains constant as the signal frequency var ies
227. tion see Appendix D Enter the Setup 2 menu Press the DEVICE OPO MO_CRYS PO_CRYS softkey Press the up down buttons until MO_CRYS appears in the menu box then press the DEVICE softkey until it beeps Select the METHOD softkey Press the up down buttons until Y_SHIFT appears in the menu box Press the METHOD softkey until a beep it beeps A menu should appear which displays the MO monitor Use the up down keys to maximize the output level on the power meter Press the CONT button Press the SAVE button Optimize the Master Oscillator 5 22 Note Optimizing Output Power 1 Turn off the MOPO HF controller to allow the primary sine bar drive gear wheel to be rotated manually For the next two steps use your right hand to adjust the MO BBHR and your left hand to rotate the gear wheel This simplifies the adjustment sequence and minimizes the chance for putting a hand or arm in the beam path 2 Note the output power on the power meter then adjust the MO BBHR vertical control clockwise just until power starts to fall Installation and Alignment 3 Rotate the sine bar gear wheel manually to optimize output power If the peak output power is lower than that noted in Step 2 repeat these last two steps this time turning the MO BBHR control counter clock wise Repeat the above two steps until output power is maximized 5 In order to ensure a maximum wavelength tuning range the output should no
228. to the MOPO HF controller where they are interpreted and implemented These messages are organized into two categories com mands and queries Commands direct the MOPO HF to store a setup parameter or execute an operation whereas queries interrogate the MOPO HF for a stored parameter value or for an operating status Using these predefined command messages a terminal can provide man ual interactive control of the system via the serial connection Messages are sent from the terminal keyboard and status responses are returned to the video monitor A computer can also provide automatic control in addition to interactive control and it can use either interface For automatic control a program designed by the user and based on the command messages can be run on the computer to step the controller through a sequence of opera tions B 1 Quanta Ray MOPO HF Optical Parametric Oscillator Interface Commands The following list of remote commands and queries provide full control of the MOPO HF system through either the RS 232 serial or IEEE 488 paral lel interface Effort has been made to create an interface that is compliant with IEEE 488 2 Refer to the IEEE 488 2 document for further information Setup Operations and Queries Basic syntax To setup or query the scan start wavelength write the command using the following syntax Setup source begin Xxx xxxx Query source begin Commands source begin XXx Xxxx source end xx
229. tral portion of the grating Figure 5 4 Verify this Verify the beam reflected off the grating hits the center of PH Due to alignment tolerances the beam may not perfectly overlap the pinhole If the beam is off set from PH by less than one beam diameter approximately 2 mm perform the following a Adjust R TM to overlap the beam on PH b If necessary adjust R TM to overlap the beam onto PH c Iterate these adjustments until the beam is centered in both pinhole apertures d Verify the beam is centered in the grating Place PH back into the beam path If necessary recenter the aperture on the beam Caution Customers should contact a service engineer if there are difficulties in obtaining the desired alignment 17 5 10 The retroreflection from the tuning mirror should be centered on pin hole PH 3 Installation and Alignment The retroreflection may be viewed on the flat side of pinhole PH by carefully rocking the tuning mirror plate that is attached to the sine bar mechanism Note that the displacement is in the horizontal plane If the retroreflection is not overlapped with PH 3 perform one of the following a If the beam is displaced by less than 2 mm from the pinhole a slight vertical and or horizontal adjustment of R TM may be neces sary to overlap the retro reflection with the pinhole b A beam displacement of less than 2 mm is most likely due to an inaccuracy in reproducing the re
230. tum noise fluctuations result in the parametric generation of signal and idler photons These photons have an intrinsic gain bandwidth that is deter mined by the dispersion of the BBO crystal Factors such as pump beam bandwidth and divergence as well as crystal length also effect the paramet ric gain bandwidth After exiting the crystal the photons interact with the grating at the grazing incidence angle The idler photons deflect out of the cavity in the zeroth order mirror reflection while the resonated signal photons diffract off the grating at an angle given by diffraction theory Osing A 3 The quantity amp is the grating groove spacing and A is the wavelength As shown in Figure 3 4 the signal photons diffracted off of the grating form a fan of wavelengths The tuning mirror is oriented to reflect the signal photons centered at the peak of the crystal gain bandwidth These spec trally narrowed photons are retroreflected into the cavity where they make a second pass through the crystal in a direction that opposes the pump beam 355 nm Diffraction Grating 4 Eu BBO Broadband Xtal High Reflector Tuning Mirror Pump In MO TMg Figure 3 4 The MOPO HF Master Oscillator uses a Grazing Inci dence geometry to produce sub 0 075 cm mean linewidths The wave length centered at the peak of the BBO gain bandwidth 1 is reflected back into the cavity while those at the edge of the gain bandwi
231. uitable to achieve seeded operation tens of microjoules is sufficient to seed the oscillator Successful injection seeding of the power oscillator requires that the phase match angle of the power oscillator crystal be identical to that of the master oscillator crystal Thus the angle which the pump beam makes with the optic axis of the two crystals must be the same This frequency overlap pro cess is accomplished with an independent adjustment of the power oscilla tor crystal angle When frequency overlap is achieved injection seeding will result In seeded operation the output power of the power oscillator will increase due to reduction in the oscillation threshold Threshold reduction occurs when there are seed photons with appropriate polarization and fre quency present at the beginning of the pump pulse These injected pho tons overwhelm those that are produced from quantum noise fluctuations in the crystal As a result it takes fewer round trips through the cavity are required to reach oscillation threshold Thus more of the pump pulse is depleted and a proportional increase in output power is realized The injected seed photons determine the nature of the spectral bandwidth of the power oscillator Therefore if an unseeded power oscillator with a free running bandwidth of 10 cm is injection seeded with sub 0 1 cm linewidth source the output linewidth will collapse to sub 0 1 cm Description Optimal
232. used with laser optics must be applied with extreme care and attention to detail Clean is a relative term as nothing is ever perfectly clean nor do cleaning operations ever completely remove contaminants Cleaning is a process of reducing objectionable material to an acceptable level Since cleaning simply dilutes contamination to the limit set by solvent impurities solvents must be as pure as possible Use spectroscopic or elec tronic grate solvents and leave as little solvent on the surface as possible As any solvent evaporates it leaves impurities behind in proportion to its volume Avoid re wiping a surface with the same swab a used swab and solvent will redistribute contamination it will not remove it Both methanol and acetone collect moisture during prolonged exposure to air Avoid storage in bottles where a large volume of air is trapped above the solvent Instead store solvents in small squeeze bottles from which trapped air can be removed Laser optics are made by vacuum deposited microthin layers of materials of varying indices of refraction on glass substrates If the surface is scratched to a depth as shallow as 0 01 nm the operating efficiency of the optical coating will be reduced significantly Quanta Ray MOPO HF Optical Parametric Oscillator Stick to the following principles whenever you clean any optical surface Remove and clean one optical element at a time If all of the optics are removed and replaced a
233. user values will be deleted if you perform this routine The procedure for Re establishing User Defined Tables goes a step fur ther moving from general theoretical values to creating values that more closely reflect your system s alignment It does this by establishing appro priate begin and end scan points then runs a linear interpolation routine while performing a scan to establish realistic points on a theoretical curve These values are then saved as the new user table The Lagrangian Table Writing Procedure then refines these values and the Automatic Table writing Procedure fills in all the rest of the points The latter runs an automatic table writing routine that is based on the begin and end wavelength values you set for a scan e g 440 and 690 nm if you performed the previous three procedures or if you are using this procedure during normal operation any other values you choose for a narrower area of interest The scan stops and samples beam power every nm then writes the best value to the table It then moves on to the next nm until the entire 6 27 Quanta Ray MOPO HF Optical Parametric Oscillator scan is complete This routine can take quite a while to run depending on the size of the scan range For normal day to day operation only use the Automatic Table writing Procedure This will keep your user table optimized and up to date General Table Writing Procedure 6 28 First verity the sy
234. x xxxx source shots KAKAK source incr XXX XXXX source scans XXXX source rate XXX source goto XXX XXXX source units x source beginwn XXXXX XX source endwn xxxxx xx source wnincr XXXXX XX source gotown XXXXX XX source mmode x Read Only Commands Basic syntax read wlen Commands read wlen read moscpwr read moscavg read poscpwr read poscavg read count Execution Commands scan hold resume scan start wavelength in nm scan end wavelength in nm shots to dwell for incremental scan incremental scan increment number of scans to perform scan speed in nm s 0 250 max goto wavelength in nm 0 nm 1 cm scan start wavenumber in cm scan end wavenumber in cm scan wavenumber increment in cm goto wavenumber in cm 0 standard mode 1 micromode 1 gives the current wavelength in nm current wavelength in nm detector level of most recent shot 16 shot rolling average power oscillator detector rolling average current scan count execute scan hold scan or goto resume scan or goto abort exegoto recall x isave x movfwr movbwr mmovfwr mmovbwr wnmovfwr wnmovbwr setmode setunits trkenbl trkdsbl tmoenbl Wrttbl abrttbl IEEE 488 2 Mandatory Commands Basic syntax SRE x SRE Commands CLS ESR IDN OPC RST SRE ESE STB TST WAI The RS 232 IEEE 488 Interface abort scan goto or table writing operation
235. you to move the MOPO HF FDO to the beginning and ending points for the scan range where you man ually optimize beam power at each point It then recomputes a theoretical curve between these points This is an effective method for quickly optimizing small wavelength regions Operation LAGRNG Lagrange performs a curve fitting algorithm over a large pre scribed scan range set up under the Setup menu The begin ning scan wavelength has to be less than the ending wavelength and with regard to the MOPO HF FDO the wavelengths must be appropriate for the selected device This algorithm cycles through 7 points within the scan range you specified and it computes a higher order polynomial fitted curve to those points This method is very effective for large wavelength ranges It is intended to get the instrument close enough in calibration for the tracking system to take over There is a minimum scan set up range of 6 nm LSQ_MRQ provides a least squares Levenberg Marquardt fitting routine that includes values for 10 points It is primarily intended for use with the MOPO HF FDO PB prism to improve its pointing stability You might have to experiment with this method and the LAGRANG method in order to determine the optimum curve fit for your application MO_AUTO performs an automatic table writing routine for the master oscillator based on the beginning and ending scan values set in the Setup menu Starting with the beginning scan wavel
236. ystal The function buttons allow you to e display the system serial number software version and track date update the operating system firmware the PCMCIA card causes the unit to perform a self diagnostic reference check for wave length grating calibration The Setup1 Menu page 6 15 is displayed when the SETUP button is pressed OPERATE1 SETUP1 MONITOR1 900 0000 1220 814nm BEGIN 500 000 END 650 000 It displays e Signal large and idler small output wavelength if SIGNAL is selected in the Operate 2 menu or e Idler large and signal small output wavelength if IDLER is selected in the Operate 2 menu or e MOPO HF FDO large doubled output wavelength and MOPO HF source wavelength small if FDO was selected in the Operate2 menu Refer to your MOPO HF FDO User s Manual for more information The function buttons provide a means to set up e the number of scans to be performed 6 9 Quanta Ray MOPO HF Optical Parametric Oscillator 6 10 e the starting and end wavelength for a SCAN e the system for a CONTinuous scan at a user defined rate or for an incremental scan with dwell points at user defined pre set wavelengths and a preset number of SHOTS given at each dwell Once a scan begins progress menus are displayed for monitoring the scan The Setup2 Menu page 6 17 is displayed when the SETUP button is pressed once from the Setup menu 900 0000 1220 814n

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