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Opal - Spectra

1. Beam Splitter Motor controlled Mirror Crystal Assembly Figure 4 2 Opal Cavity Layout 4 2 Warning m Controls Indicators and Connections Iris facilitates in aligning the Opal pump beam It has a lever to set the iris size Do not move the mount from its factory set position or you will be unable to properly align the system Pump beam mirror P4 directs the pump beam onto focus mirror P It has vertical and horizontal adjustments Pump beam mirror P directs and focuses the pump beam through cav ity focus mirror M and into the LBO crystal It has vertical and horizontal adjustments and a translational control for adjusting the beam focus in the crystal A setscrew locks the translation dovetail stage in place Cavity mirror M focuses the cavity beam into the crystal then directs it onto cavity focus mirror Ms It also directs the cavity beam through iris l and onto the center of cavity mirror M It has vertical and horizontal con trols for steering the cavity beam and a translation control for focusing the cavity beam in the crystal A setscrew locks the translation dovetail stage in place LBO crystal generates two new phase matched frequencies Signal and Idler from a coherent pump source These new frequencies are dependent on the temperature of the crystal refer to Chapter 3 The crystal assembly contains a heater and temperature sensor assembly It h
2. 36 00 1 50 Description 8 50 2 15 10 16 8 00 5 46 20 32 2 3 to 3 8 OPAL Input End f H F ao16 0 9 to 1 5 17 00 91 44 24 00 60 96 OPAL side view 43 18 5 25 13 34 na 0 81 G Spectra Physies OPAL Electronics Module Front View Figure 3 8 Outline Drawings References Spectra Physics 8 81 21 60 0000000000000 0090000000000 0000000010000 0000000000000 UJ UJ o All dimensions in OPAL Electronics Module Side View inches D C Edelstein E S Wachman and C L Tang Appl Phys Lett 54 1728 1989 E S Wachman D C Edelstein and C L Tang Opt Lett 15 136 1990 W S Pelouch P E Powers and C L Tang Opt Lett 17 1070 1992 P E Pow ers S Ramakrishna C L Tang and L K Cheng Opt Lett 18 1171 1993 P E Powers C L Tang and L K Cheng Opt Lett 19 37 1994 and P E Powers C L Tang and L K Cheng Opt Lett 19 1439 1994 7 Q Fu G Mak and H M van Driel Opt Lett 17 1006 1992 3 A Nebel C Fallnich R Beigang and R Wallenstein J Opt Soc Am B 10 2195 1993 TJ Driscoll G M Gale and F Hache Opt Commun 110 638 1994 3 JD Kafka M L Watts
3. 1 ea bid M 5 0451 7233 SEE MANUAL 0453 9600 CE Warning Label 9 Voltage Current Rating Label 11 Figure 2 5 CE CDRH Warning Labels 2 6 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 Table 2 1 Label Translations Label French German Spanish Dutch Danger Attention Rayonnement Vorsicht Austritt von sicht Peligro al abrir y retirer el Gevaar zichtbare en niet Interlocked Laser visible et invisible en barer un unsichtbarer dispositivo de seguridad zichtbare laser straling Housing cas D Ouverture et lor Laserstruhlung wenn exist radiacion laser visible wanneer geopend en bij Label sque la securite est neutra Abdeckung geoffnet und e invisible evite que los uitgeschakelde interlock 3 lisse exposition Sicherhetisschalter uber ohos o la piel queden Vermijd blootstelling van dangereuse de l oeil ou de bruckt Bestrahlung von expuestos tanto a la radia 00g of huid aan directe la peau au rayonnement Auge oder Haut durch cion dircta como a la dis straling of weerkaatsingen dirct ou diffus direkte oder Streustreus persa daarvan trahlung vermeiden Caution Attention Rayonnement Achtung Sichtbare und Precauci n radiaci n peli Let op Zichtbare en Interlocked visible et invisible dan uns
4. nd Opal Controller Figure 2 4 CE CDRH Radiation Control Drawing Back Panel ka 2 5 Opal fs Synchronously Pumped Optical Parametric Oscillator CE CDRH Warning Labels Spectra Physics 1344 TERRA BELLA AVENUE MT VIEW CALIFORNIA 94039 MANUFACTURED Spectra Physics MONTH YEAR MODEL NUMBER MODEL S N SERIAL THIS LASER PRODUCT COMPLIES NUMBER WITH 21 CFR 1040 AS APPLICABLE MADE IN U S A MADE IN U S A 404471 Certification Label OPAL 1 Serial Number Label Controller 2 VISIBLE AND INVISIBLE LASER RADIATION WHEN OPEN VISIBLE AND INVISIBLE 4 AND INTERLOCK DEFEATED HAZARDOUS ELECTROMAGNETIC AVOID EYE OR SKIN EXPOSURE RADIATION WHEN OPEN AND TO DIRECT OR SCATTERED INTERLOCK DEFEATED RADIATION SEE MANUAL SEE MANUAL Danger Interlocked Caution Interlocked CE Certification Housing Label 3 Housing Label 4 Label 5 ANG INVISIBLE C ASER RADIATION IS me CDRH Aperture Label 6 CE Aperture Label 7 CE Caution Label 8 REPLACE THE BATTERY WITH THE SAME OR EQUIVALENT TYPE RECOMMENDED BY THE MANUFACTURER VISIBLE AND OR INVISIBLE DISPOSE OF USED BATTERIES ACCORDING LASER RADIATION TO THE MANUFACTURER S INSTRUCTIONS AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION PONER AELE GTA ANO HULSE Battery Replacement Label 10 WIDTH DEPEND ON PUMP OPTIONS AND LASER CONFIGURATION EN60825 1 1994
5. 150 L meters Rep Rate MHz where L is the effective cavity length 5 9 Opal fs Synchronously Pumped Optical Parametric Oscillator Example If the Tsunami repetition rate is 80 150 MHz its effec tive cavity length L is 150 divided by 80 150 or 1 871 meters Warning Y The spacing between M and M is factory set and should never require realignment Therefore unless you are sure this spacing has been changed DO NOT perform Steps 3 and 4 3 Space M and M 111 mm apart as shown in Figure 5 4 4 Set the initial position of P 81 mm from M as shown in Figure 5 5 Figure 5 4 M and M Spacing 81 mm M Figure 5 5 P and M Spacing 5 5 10 Set the cavity length of the Opal to match the cavity length of the Tsu nami laser a b From the Setup menu initiate a Scan Length command This ensures the software recognizes the polarity of the motor Set M to the center of its range Use the Manual Control menu and the up down push buttons on the electronics module to set Motor to a 50 value Refer to Chap ter 4 for the menu flow chart and menu descriptions Using a metric scale measure the spacing between the front face of each tilt plate not the mirror itself for mirrors M M M M M3 Add the total distances Add 98 mm to the total distance The 98 mm compensates for the fact that the mirrors are recessed from the front face o
6. 800 nm System D fs cm SF 10 Brewster Prism pair double pass 80 2 BK 7 Brewster Prism pair double pass 12 8 Grating pair 400 lines cm 1500 30 incidence angle double pass Grating pair 1000 lines cm 10 000 30 incidence angle double pass The prisms are double passed to maintain the spatial profile of the beam If only one pass through the prism is used the output is spatially chirped While the spacing of the prisms provides negative dispersion the prism material actually adds more positive dispersion to the system This can be used to our advantage to optimize a prism pre compensator For an initial setup based on your Tsunami and Opal and a Model 409 08 autocorrelator set the prisms approximately 30 cm apart at Brewster s angle to the beam with the high reflector a few cm from the second prism With this spacing the prism pair should start with excess negative GVD By moving the prism tips into the beam we can balance the GVD for minimum pulse width To do this place the first prism on a translation stage that moves the prism in the direction of the bisector of the apex This way more glass can be pushed into the beam path without displacing the beam or changing its angular direction This allows the negative GVD of the prism system to balance the positive GVD created by all the glass By moving the GVD Compensation prism into the beam path and monitoring the pulse with a Model 409 08 the pulse should
7. Scanning Signal from 1 350um to 1 450um SCAN 1 The Scan Status menu reports to the Scan menu It displays the status of the scan showing the Signal wavelength limits set in the Scan menu as well as the relative position of the scan within those limits The box in the upper right displays the selected wavelength for the Signal and Idler System sta tus comments are displayed just below the box Soft Keys Pause Scan pauses the scan and brings up the Paused Scan Status menu Paused Scan Status Menu SCAN sant asim LOO to 1 450um 2 003um SCAN 1 PAUSED EH The Paused Scan Status menu reports to the Scan Status menu It is just like the Scan Status menu except it shows the scan paused and the soft keys change to allow the operator to either resume the scan or abort it Abort the scan to change parameter settings once the scan has started Soft Keys Resume Scan resumes the scan after a pause and returns to the Scan Sta tus menu Abort Scan allows the operator to abort the scan and resume other func tions via the Scan menu From there the scan parameters can be reset and another scan started or the Main menu can be recalled Opal fs Synchronously Pumped Optical Parametric Oscillator Remote Menu REMOTE Please select a Power PZT remote control mode The Remote menu reports to the Main menu It allows the control interface to be set to RS 232 IEEE 488 or LOCAL The RS 232 and IEEE
8. Turning On the System 6 2 Under normal day to day operation the operator need only perform the fol lowing to use the system 1 Turn on the Millennia pump laser and allow it to warm up according to its user s manual At the same time turn on the Tsunami and Opal electronics modules if not already on and allow them to warm up and stabilize at least 15 minutes 2 If operating the Tsunami or the Opal in a region affected by oxygen or water absorption purge the cavity of one or both systems Refer to the Tsunami User s Manual for information on oxygen and water absorption regions that affect the performance of the Tsunami laser and refer to Figure 6 1 in Purging the Opal on page 6 5 to find the regions that affect the Opal Refer to Chapter 5 Installation and Alignment Attaching the Opal Purge Line for information on install ing a purge for the Opal 3 Check the Tsunami laser for power and mode and set it to a wave length appropriate for driving the Opal at the chosen wavelength Refer to the Tsunami user s manual and to Table 6 1 to set the Tsunami wavelength 4 Adjustthe Millennia output power to about 10 W This should provide 22 W of power from the Tsunami Operation Table 6 1 Typical Settings for Several Opal Wavelengths Opal Pump Nom Grating Nom Crystal Wavelength um Wavelength nm Setting steps Temperature 1 100 750 3673 66 1 150 750 3420 66 1 200 775 3166 85 1 250 775 2910 67 1 300
9. Warning Unless expressly stated otherwise perform the following procedures with Tsunami output power set to minimum Initial Set up Close the Opal shutter 2 Calculate the physical cavity length of the Tsunami laser a Setthe Tsunami wavelength to 810 nm b Optimize the Tsunami output beam quality with 2 W of output power Ensure the laser is mode locked with a stable pulse train refer to Tsunami manual c Adjust the pulse width to about 100 fs i e such that the output pulse width has about 9 nm of bandwidth d Use a frequency counter to obtain the Tsunami repetition rate This can be done conveniently by connecting the MONITOR output of the Model 3955 to a frequency counter The effective cavity length is calculated using the following equation 1 L meters Mes Rate MHz H where L is the effective cavity length Example If the Tsunami repetition rate is 80 150 MHz its effec tive cavity length L is 150 divided by 80 150 or 1 871 meters realignment Therefore unless you are sure this spacing has been Warning W The spacing between M and M is factory set and should never require changed DO NOT perform Steps 3 and 4 3 Space M and M 111 mm apart as shown in Figure 5 4 Set the initial position of P 81 mm from M as shown in Figure 5 5 5 Setthe cavity length of the Opal to match the cavity length of the Tsu nami laser 5 19 Opal fs Synchronously Pumped Optical Parametric Oscill
10. this wavelengt Clear Back Ploint The Clear menu reports to the Adjust Temp menu It can be used to either clear the working table of all temperature offsets or clear a single point Prior to clearing anything verify the wavelength whose temperature offsets are to be cleared has indeed been selected on the previous menu If clearing a single point verify the correct point is selected figure menu the user modified offset table will be unrecoverable once the Clear All soft button is pushed under the Clear menu or the unit is turned off To restore the table if it was not saved requires the operator to re enter every offset one at a time Caution W If the table has not been saved using the Save Recall function in the Con Soft Keys Clear All clears the entire working table of all temperature offsets and restores defined system values for the wavelength selected When this but ton is pressed a warning appears informing the operator that the entire table is about to be erased To restore the table if it has not been saved requires the operator to re enter every offset one at a time To save it use the Save Recall feature in the Configuration menu Clear Point clears the single temperature offset point selected in the pre vious menu and restores the defined value or an interpolated value for that point Back returns to the previous Adjust Temp menu 6 14 Operation Setup Menu SETUP SETUP Optics se
11. Save Recall brings up the Save Recall menu where special setups can be saved or recalled Misc brings up the Miscellaneous menu where the wavelength display units can be selected or the parameters set for the optional RS 232 and IEEE 488 interfaces Diagnostics brings up the Diagnostics menu where the critical operating parameters are displayed and the system functions can be manually set Go to Idle places the system in standby mode for overnight shutdown Main Menu returns to the Main menu Save Recall Menu CONFIGURATION Save Recall Setup Save Recall configuration 1 Recall The Save Recall menu reports to the Configure menu It allows special sets of scan parameters with optimized temperature offsets to be stored and retrieved Use the up down push buttons to select the configuration mem ory address The parameters stored at O are used when the system starts up place your most often used configuration at this address You can also save configurations in numbers 1 through 6 Numbers 7 through 9 are saved as system read only configurations Mem ory 7 has the factory stored final test parameters for the 1 5 um optics set with 810 nm pump Memory 8 has the final test parameters for the 1 3 um optics set with a 775 nm pump and memory 9 has the final test parameters for the 1 3 um optics set with a 750 nm pump System comments are shown in the center of the screen Opal fs Synchronously Pu
12. and J W Pieterse CLEO Vol 11 OSA Tech Digest Series 1993 CPD32 p 69 3 9 Opal fs Synchronously Pumped Optical Parametric Oscillator 3 10 Chapter 4 Control Indicators and Connections This section defines the user controls indicators and connections of the Opal system and it is divided into two main sections the Opal Head and the Opal Electronics Module Refer to Figure 4 1 Figure 4 3 and Figure 4 4 Opal Head Figure 4 1 shows the location of the controls and connections on the Opal head Their functions are described on the following pages M 1 5 um End Mirror Pr 1 3 um Operation Pr 1 3 um Operation Mz 1 3 um End Mirror P Pump Mirror M Output Coupler Pump Input Residual Pump Output Opt Signal Output Idler Output Servo Connector Green Knob Horizontal Adjust Blue Knob Vertical Adjust Heater Controller Connector N Purge Input Connector N Purge Bleed Valve Figure 4 1 Opal Head Controls and Connections 4 1 Opal fs Synchronously Pumped Optical Parametric Oscillator Input Bezel Connections The input bezel connections attach to the Opal electronics module and to a nitrogen purge supply source usually to a Model 3910 filter drier unit Purge bleeder valve when open allows more purge gas to flow through the Opal head when the system is first turned on Once the unit is well purged it is closed during operation to reduce nitrogen consumption Purge i
13. mented These messages are organized into two categories commands and queries Commands direct the Opal to store a setup parameter or execute an operation whereas queries interrogate the Opal for a stored parameter value or the status of an operation Using these predefined command messages a terminal can provide man ual interactive control of the system via the serial connection Messages E 1 Opal fs Synchronously Pumped Optical Parametric Oscillator are sent from the terminal keyboard and status responses are returned to the video monitor A computer can also provide automatic control in addi tion to interactive control and it can use either interface For automatic control a program designed by the user and based on the command and queries listed in this appendix can be run on the computer to step the con troller through a sequence of operations Format and Syntax Rules Commands E 2 All commands and responses are in ASCII format Commands to the Opal system must be terminated by an ASCII carriage return line feed or both All responses from the Opal are terminated by an ASCII line feed character In the examples below a carriage return is indicated by cR and a line feed by Lr 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
14. slightly in one direction and note the change in output power c If it increased continue to turn until power starts to drop If it decreased turn the screw in the opposite direction When power is optimum lock the P setscrew then verify power remained optimum Opal fs Synchronously Pumped Optical Parametric Oscillator 3 Replace the Opal cover Make sure you do not bump any control knobs 4 From the Setup menu verify the operating parameters are correct i e the Tsunami pump wavelength and the Opal optics set is correctly selected then run the Scan Length command This will calibrate the wavelength and set the default crystal tempera ture to either the previously stored settings or to the factory pro grammed temperature offset 5 From the Main menu adjust the output wavelength to 1 300 um using the up down keys 6 Use a monochromator to measure the output Signal wavelength If the wavelength readout differs from your actual measured wave length by more than 3 nm perform the following Otherwise skip to Step 7 For reference Table 5 1 shows relative values for various sys tem components for an Opal output of 1 300 um Table 5 1 Typical Settings for Opal Output at 1 300 um Opal Pump Nom Grating Nom Crystal Wavelength um Wavelength nm Setting steps Temperature 1 300 775 2652 55 a From the Diagnostic menu press Cal Wavelen to get to the Wave length Calibration sub menu b Sel
15. 4 3 10 1 0000 a 2 2 Figure 2 2 Folded Metal Beam Target 2 0 c eee tee eee 2 2 Figure 2 3 Laser Head Shutter Interlock 0000 cee ren 2 3 Figure 2 4 CE CDRH Radiation Control Drawing anaana eae 2 5 Figure 2 5 CE CDRH Warning Labels 2 0 00 cece teens 2 6 Figure 3 1 A Typical Optical Parametric Oscillator Configuration llis 3 2 Figure 3 2 Optical frequency three wave conversion process 20000ce eee eee eee 3 2 Figure 3 3 Typical System Setup ccc ete eee 3 3 Figure 3 4 Signal and idler wavelengths are tuned by changing the temperature of the LBO crystal 3 3 Figure 3 5 The Opal Tuning Curves 2 00000 hr 3 4 Figure 3 6 Opal Cavity Beam Path 0 000 c teen eeee 3 4 Figure 3 7 Wavelengths most affected by vapor absorption 0 a 3 7 Figure 3 8 Outline Drawings isses RR I mr 3 9 Figure 4 1 Opal Head Controls and Connections 0 00 c eee eens 4 1 Figure 4 2 Opal Cavity Layout 0 0 00 hm 4 2 Figure 4 3 Front Panel Opal Electronics Module 20 0000 c eects 4 5 Figure 4 4 Rear Panel Opal Electronics Module 0 00 cece eee eens 4 6 Figure 5 1 Opal system layout with a Tsunami Mode Locked Ti sapphire Laser and a Millennia Diode Pumped Pump Laser 0 0 5 2 Figure 5 2 Opal Cavity Layout 0 0 0 0 00 ccc eee 5 7 Figure 5 3 Transmittance vs wavelengths for wa
16. 488 inter faces are options and may not be available on your system The system starts up with the LOCAL interface active but by changing to either the RS 232 serial or IEEE 488 parallel link the system can be controlled from an external remote source For more information on the optional interfaces please call the factory Soft Keys RS 232 selects the RS 232 serial interface as the control source IEEE 488 selects the IEEE 488 parallel interface as the control source LOCAL returns control to the front panel Adjust Temp Menu ADJUST TEMPERATURE Signal 1 500um Signal 1 500um Idler 1 761um Idler 1 761um Temp Table Single Point Power PZT Shift 0 096 Power PZT Offset 6 1 Next Shift Clr All Help Main Next Shift Clr All Help Main Field Point Offsets Menu Field Point Offsets Menu The Adjust Temp menu reports to the Main menu It provides two methods Temp Table Shift and Single Point Offset for optimizing Opal performance pulse width stability output power etc at a particular wavelength To obtain different signal and idler output wavelengths the phase matching conditions in the Opal are varied by changing the temperature of the LBO crystal For a particular signal wavelength the appropriate crystal tempera ture measured as a percentage 0 to 100 is recalled from a stored set of theoretical phase matching curves based upon the Tsunami pump wave length specified in the Setup menu However s
17. Module LCD screen displays the menu driven program It shows the status of a variety of parameters depending on the menu displayed including Signal or Idler wavelength stepper count grating position motor position in percent of total range loop status on off crystal temperature in percent of total range servo status scan status interface modes selectable com mands and field variables Help menus are also displayed to provide assis tance Soft keys 5 refers to the five push buttons below the display that are defined by the currently displayed menu Press the buttons to select other submenus to select data fields in the menu displayed or issue commands directly such as Run Scan Length or Save Setup Up down push buttons increase or decrease the value displayed in the selected field e g crystal temperature motor position grating position etc 4 5 Opal fs Synchronously Pumped Optical Parametric Oscillator Rear Panel Figure 4 4 shows the location of the various cables and switches on the Opal electronics rear panel On off power switch turns on and off power to the electronics module Power cord connector provides connection for the power cord On Off Switch Power Cord Voltage Selector Future Accessories e WAVELENGTH PZT POWER STABILIZED MONITOR MONITOR TO OPAL HEAD Fan Wavelength PZT Power Opal Head Heater Stabilized Monitor
18. RS 232 C Interface to a Standard 25 pin PC Com Port DTE RS 232 C DCE Device communications Link Device PC Computer Opal 25 Pin Standard 9 Wire 25 Pin Connector Serial Interface Cable Connector 1 Protective Ground 1 7 Signal Ground 7 2 Transmitted Data 2 3 Received Data 3 4 Request To Send 4 5 Clear To Send 5 6 Data Set Ready 6 8 Data Carrier Detect 8 20 Data Terminal Ready 20 Table E 2 RS 232 C Interface to a Standard 9 pin PC AT Com Port DTE RS 232 C DCE Device communications Link Device PC Computer Opal 9 Pin PC AT 9 to 25 Pin 25 Pin Connector Serial Interface Cable Connector shell Protective Ground 1 5 Signal Ground 7 3 Transmitted Data 2 2 Received Data 3 7 Request To Send 4 8 Clear To Send 5 6 Data Set Ready 6 1 Data Carrier Detect 8 4 Data Terminal Ready 20 Signals of the communications link are named with respect to the DTE device E 6 Notes Notes 1 Opal fs Synchronously Pumped Optical Parametric Oscillator Notes 2 Notes Notes 3 Opal fs Synchronously Pumped Optical Parametric Oscillator Notes 4 Notes Notes 5 Opal fs Synchronously Pumped 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 call or letter to our service department but that you f
19. Synchronousl SCAN Signal Idler from S00 2 149um to T 1 620um step 0 001 um dwell 0 5 sec 1 times Scan Status Scanning Signal from 1 300um to 1 620um SCAN 1 Paused Scan Scanning Signal from 1 300um to 1 620um SCAN 1 Pumped Optical Parametric Oscillator Main Menu L 1 761um Setup Scan Remote Adj Ctrl Temp Config CONFIGURE Configure DIAGNOSTICS 1 1 1 CONFIGURE 1 i Please select a PZT remote control mode Save Misc Diag Goto Main Recal nostics Idle menu 1 Save Recall Diagnostics Save Recal Setup DIAGNOSTICS Idler 1 761um Temp Table Shift 0 0 Save Recall configuration 1 2168cts Loop is ON Manual Cal About Ctrl Wavelen Opal Next Field Shift Point Cir All Offsets Main Menu Help Save Recall menu Miscellaneous Manual Control i 1 i Signal 1 500um 1 Idler 1 761um gtng 1 500um i Motor 50 2 Loop is ON i 1 1 Back Single Point 88 2 Offset 6 1 Parity None Power PZT Stop Bits 1 Next Shift Field Power PZT Err Next steps Loop Scan Field um On Off Length Cir All Offsets Main Help Menu Point Scanning Coarse Length SCANNING COARSE LENGTH Scanning reverse SETUP Optics set 1 3 1 6 BTO nm pump assumed Check that Tsunami is at 810 nm CLEAR OFFSET
20. a single point offset upon return to the Diagnostics menu If any of the three conditions are not true the temperature setting will be ignored and the setting that existed prior to going to the Manual Control menu will be used 6 20 Operation Scanning Coarse Length Menu DIAGNOSTICS SCANNING COARSE LENGTH Scanning reverse ee TJ The Scanning Coarse Length menu reports to the Manual Control menu It dynamically displays a scan search for the Tsunami Opal cavity match point i e the point where the Opal cavity matches that of the Tsunami laser or where the round trip time of the signal pulse in the Opal cavity matches that of the pump pulse in the Tsunami If the scan is successful i e the Opal flashes and oscillates the scan stops immediately This scan differs from that available from the Setup menu in that there is no automatic calibration Successful or not you are returned to the Manual Control menu Soft Keys Abort Scan stops the scan and immediately returns to the Manual Control menu Wavelength Calibration DIAGNOSTICS Wavelength Calibration Set actual wavelength 1 500 Then press Set Cal key Zeroth Order at 9559 Modify the field values in this menu only when you are following the instructions for calibrating the servo wavelength monitor as outlined in Appendix C This menu is not normally used The Wavelength Calibration menu reports to the Diagnostics menu Use this menu periodicall
21. amount of fre quency doubled light observed on the card The frequency doubled blue light is collinear with the Opal intracavity beam and can be used to align the Opal cavity The beam appears as a figure 8 as shown in Figure 5 6 Remove the card then adjust M vertically and horizontally to direct the blue beam to the center of the front face of M 5 21 Opal fs Synchronously Pumped Optical Parametric Oscillator 4 To increase the intensity of the second harmonic beam remove the output coupler at M and replace it with the additional high reflector provided in your optics kit Less loss will aid in the initial alignment Remember to close the shutter while changing optics 5 Adjust M to center the blue beam through iris and onto the center of the front face of M Close l a little to verify the beam is centered Iterate between adjust ments of Ms and M to center the beam through and onto M4 6 Adjust M vertically and horizontally to reflect the blue beam back through the center of iris lp then fully open p 7 Adjust M to direct the blue beam through iris and onto the center of Ms Close a little to verify the beam is centered Once centered open it fully 8 Verify the blue beam path is clear of prism Pr If it is not use the micrometer to adjust prism Pr until it is out of the blue beam path 9 Adjust M to center the blue beam onto the center of Mg 10 Adjust M to center the blue beam
22. and Idler are shown in the upper right box with the Signal wavelength shown as the larger number After performing a successful scan from the Setup menu an L will also be seen in this box to indicate the servo loop is on and the system is locked Soft Keys Scan brings up the Scan menu where the system can be set to scan a set number of times through a wavelength region in incremental steps and stop dwell at each step Remote Ctrl brings up the Remote menu where the control interface is chosen RS 232 IEEE 488 or LOCAL default Adj Temp brings up the Adjust Temp menu where the temperature of the crystal is set for optimum performance pulse width stability output power etc Setup brings up the Setup menu where the Opal optics set and Tsunami pump wavelength are chosen Config brings up the Configuration menu where often used settings are saved or recalled system diagnostics can be run or the overnight idle mode selected Opal fs Synchronously Pumped Optical Parametric Oscillator Scan Menu SCAN SCAN Signal Idler from 2 025um to 1 450 1 835um step 0 001 um dwell 0 5 sec 1 times The Scan menu reports to the Main menu It allows the operator to scan a selected number of times through a wavelength region in selected incre mental step size and have the system stop dwell for a selected time period at each step The display box shows the wavelength of the Signal and Idler output Sca
23. be added before calculating B For example D L L a D s T aron Danla Pagka PamLan 3 atot This provides a simple means for calculating the spacing between prisms necessary for compensation B 7 Opal fs Synchronously Pumped Optical Parametric Oscillator Figure B 5 B 8 Broadening to itin 0 1 0 0 1 02 0 3 04 05 06 07 08 09 10 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 S Normalized Units Broadening Curve Example 1 Calculating pulse width measured by a Model 409 08 without pre compensation Assume an 800 nm pulse at the output coupler surface of a Tsunami laser is 55 fs long and transform limited It passes through 1 9 cm of fused silica before exiting the Tsunami and 0 25 cm of BK 7 glass and 0 26 cm of fused silica in the Model 409 08 D yton latot E Danla t Pala 300 1 9 300 0 26 450 0 25 760 fs Therefore S 760 fs 55 fs 0 251 Then looking at our normalized curve Figure B 5 0 251 and B 1 22 ta 1 22 tj 67 fs out Example 2 Calculating the prism spacing necessary for pre compensating the Model 409 08 Since dispersion is additive it is only necessary to make the total disper sion equal to zero to eliminate all broadening effects This allows a direct calculation of the required prism spacing without finding the actual broad ening Again start with a 55 fs
24. cR Operation Complete Command Sets 1 the OPC bit of the Event Status Register ESR OPC cR Operation Complete Query Returns a 1 to indicate that command interpretation was completed RST cR Reset Command Loads stored configuration 0 and turns off the wavelength stabilization loop SRE xxx cR Service Request Enable Command Sets 1 the status byte mask register SRE cR Service Request Enable Query Reads the status byte mask register STB cR Read Status Byte Query Reads the status byte Its bits are defined as Bit Definition 7 reserved 6 SRQ Opal is requesting service 5 ESR Summary Bit this bit is one if the bit wise AND of the ESR and the ESE is non zero 4 reserved 3 reserved 2 WLSET wavelength is settled 1 LOOPON the wavelength regulation loop is on O reserved E 5 Opal fs Synchronously Pumped Optical Parametric Oscillator TST lt cr gt Self Test Query Returns a 1 to indicate success It does not actually run any internal tests on the Opal WAl cR Wait to Continue Command This is a no operation no op command It is used to add wait states between readings or between a command and a read It takes about 20 ms for a command to be implemented Connections The following tables explain what kind of RS 232 cable to buy or create in order to connect the Opal to an IBM PC or PC AT compatible computer Table E 1
25. day to day basis the Main menu is most frequently used All Opal operating parameters used by the microprocessor based controller are accessed through this menu The other commonly used menu is the Adjust Temperature menu It allows the operator to optimize Opal performance by changing the temperature of the lithium triborate LBO crystal which adjusts the phase matching conditions Although the Opal has a manual mode of operation that provides independent control of the operating parameters this mode should only be employed during the initial set up Since the Opal is synchronously pumped by the Tsunami laser it is neces sary to precisely match the cavity length of the Opal to that of the Tsunami This is achieved using a computerized servo system that includes a motor ized mirror mount at the output coupler M for coarse long cavity length control and a piezo electric transducer PZT driven mirror at M for rapid but small changes in cavity length The servo system also ensures excellent long term stability Once the initial alignment of the Opal has been per formed day to day operation of the Opal is achieved by simply initiating a Tsunami Opal cavity length match by issuing a Scan Length command to the servo system The desired output wavelength can then be entered through the Main menu 6 1 Opal fs Synchronously Pumped Optical Parametric Oscillator Warning ly When the wavelength is selected the computer calculates the app
26. e smaller temporal walk off of the pump and signal beams which allows the use of longer crystals for higher gain iv it has low group velocity dispersion GVD which means that over a large tuning range sub 130 fs pulses can be achieved without the use of intracavity dispersion compensation and v it can be automatically wavelength tuned since this is accomplished by changing only the crystal temperature and cavity length Figure 3 4 With respect to the latter for comparison the cavity of angle tuned system must be realigned when the OPO is tuned over a large wave length region 2 75 t 250 f 22 5 2 00 Degeneracy Idler c Point O 175 S 1 50 y Pa S 125 Signal 1 00 Lotte t ped d Temperature Figure 3 4 Signal and idler wavelengths are tuned by changing the temperature of the LBO crystal 3 3 Opal fs Synchronously Pumped Optical Parametric Oscillator Wavelength Tuning Characteristics The Opal can be pumped at any wavelength between 720 and 850 nm with 2 W of average power and 100 fs pulse widths at a repetition rate of about 80 MHz Typical output powers of the Opal for 2 W of pump power at 750 775 and 810 nm are shown in Figure 3 5 The signal pulse width is typically less than 130 fs over this wavelength range 1 1 to 1 6 um This tuning range is accomplished using only two optics sets 1 3 and 1 5 um and by temperature tuning the LBO crystal A Ti sapphire pump
27. enter that measured value 18 Select the Zeroth Order at field and enter the 0 order grating step num ber recorded in Step 10 19 Press the Set Cal push button The screen will go blank for a brief moment and then return with the system calibrated using the new values 20 Return to the Setup menu and perform a Scan Length This will take a few moments Note Do not perform Scan Length from the Manual Control menu No self calibration is performed by this function in Manual Control Use the Setup menu When Scan Length is done the system will return to the Main menu and the system will be locked and calibrated You can now set the sys tem for the wavelength you actually want to use Table C 1 shows nominal grating and temperature settings for operating at several Opal Signal wavelengths Table C 1 1st Order Settings for Several Opal Wavelengths Opal Pump Grating Nom Crystal Wavelength um Wavelength nm Setting steps Temperature 1 200 775 3133 8596 1 300 775 2651 5396 1 400 810 2128 7696 1 500 810 1596 6396 This completes the procedure for calibrating the servo wavelength monitor assembly Opal fs Synchronously Pumped Optical Parametric Oscillator C 4 Appendix D Replacing the PCMCIA Card Battery The 512 kB PCMCIA memory card found in the Opal controller uses a small 3 V disk battery to maintain the data stored in it The expected life time of the battery is approximately 2 3 years so it is prud
28. free of water or oxygen absorption refer to your Tsunami User s Manual and the Opal within a water absorption region purging the Opal with nitrogen is more efficient when the purge line is disconnected from the Tsunami and connected directly to the Opal output bezel To do this simply remove the purge line from the bezel connector of one system and plug it into the other However the two systems can easily share output from the Model 3910 by simply splicing the T connector provided into the output line and adding the second line and connector also provided gen PTFE does not introduce outgassed impurities into the cavity that Warning u Use the PTFE tubing provided with the Opal to purge it with dry nitro may degrade system performance and or damage optical coatings 5 7 Opal fs Synchronousl Pumped Optical Parametric Oscillator Transmittance 1 100 1 200 1 300 1 400 1 500 1 600 Wavelength um Figure 5 3 Transmittance vs wavelengths for water vapor in the Opal Signal wavelength range To purge the Tsunami laser and the Opal at the same time perform the fol lowing to insert the T connector into the Model 3910 output purge line 1 Use the 3 6 m PTFE purge line and tee provided in the accessory kit for this purpose The tubing has a quick disconnect connector on one end for attachment to the Opal The other end is cut flush for pressing onto the T connector Attac
29. get narrower as dispersion is balanced If a minimum can not be found adjust the prism spacing and search for the minimum again Calculating Pulse Broadening Below are some simple formulae for calculating the effects of GVD and its compensation B broadening is defined as the ratio of the output pulse width to the input pulse width where B t ftin Consequently knowing the input pulse width B can be calculated so that f B t out A simple formula for calculating the broadening of a transform limited Gaussian pulse by dispersive elements is l 2 Su dee em 68 Dy L G i 1 where 1 is the input pulse width in femtoseconds and D is a dispersion value normalized for a given length and wavelength Table B 2 gives posi tive GVD values for different materials at 800 nm Table B 3 contains val ues for negative dispersion setups prisms and grating pairs for compensation at 800 nm Using these values B is calculated directly we define S as S Do O N 2 in Using Figure B 5 you can relate the value of S to a value for the broaden ing B When using this equation and graph it is important to remember that the values of D are wavelength sensitive For example for BK 7 material the difference from 800 nm to 880 nm is 17 Therefore it is important to use the correct value of D for the operational wavelength Also if there are several materials present the values for dispersion must
30. it points away from your selection and will protrude through the correct hole in the cover plate when the plate is replaced in Step 6 4 Replace the voltage selector card Make sure the pc board seats properly for good electrical contact 5 Verify the correct fuse is installed Remove the small screw holding the fuse block to the cover plate to access the fuse Use the table below to determine the correct fuse size for your facility outlet voltage then verify the correct one is installed Table A 1 Fuse Selection Line Voltage Fuse Value 100 to 120 Vac 1A slow blow 220 to 240 Vac Ve A slow blow 6 Snap the cover plate into place If the indicator pin is not in the correct position repeat Steps 3and 4 This completes the procedure for changing the voltage setting A 2 Pulse Width Measurement Appendix B and GVD Compensation Introduction In this chapter we discuss how to measure pulses using an autocorrelator as well as how to compensate for group velocity dispersion GVD The Autocorrelation Technique Measurement of Ultrashort Pulses An autocorrelator is the most common instrument used for measuring an ultrafast femtosecond fs or picosecond ps optical pulse By using the speed of light to convert optical path lengths into temporal differences we use the pulse to measure itself The basic optical configuration is similar to that of a Michelson interferom eter An incoming pulse is split into two pulses
31. normal for an increase in temperature to be more rapid than a decrease A flashing arrow symbol 7 in the box indicates the system has not stabilized Allow the system to stabilize before continuing The PZT bar graph indicates how well the servo is tracking When the sys tem is operating correctly the small bar will move very slightly about the center position To keep it in the center the servo system moves the M mir ror to compensate for large slow changes in cavity length The PZT mounted M moves quickly to respond to smaller rapid changes The box in the upper right corner of the screen shows the selected wave length for the Signal and Idler Opal fs Synchronously Pumped Optical Parametric Oscillator Soft Keys Next Field moves the highlight box surrounding the Signal field to the Temp Table Single Point Offset field and back again so that the wavelength or temperature variable can be changed using the up down push buttons Shift Point allows the temperature setpoint to be changed by either shift ing the entire table all points are offset in the same direction by the same amount or offsetting a single point in the table Clear Offsets brings up the Clear menu where either the working table of all temperature offsets or a single point can be cleared Main Menu returns to the Main menu Clear Menu ADJUST TEMPERATURE CLEAR OFFSETS All Clear all offsets in this in se Point clear only the ne at
32. on mode locking in the Wrong pump wavelength is Tsunami User s Manual Set up wavelength detection device monochromator and tune the Tsunami selected for the desired Opal laser for the correct wavelength Refer to the Table 6 1 in this manual to verify output Low pump power that the Tsunami pump wavelength is appropriate for your desired Opal wavelength Allow the Millennia and Tsunami lasers to warm up about 10 15 min then adjust both lasers for a 2 W output from the Tsunami Incorrect Opal cavity length set Verify cavity spacing is correct Refer to Chapter 5 Installation and Align Incorrect crystal temp is selected Opal is misaligned ment Opal Alignment Initial Setup for the optics set you are using 1 3 or 1 5 um Initiate a Scan Length from the Setup menu to determine the proper crystal temperature Verify the correct wavelength is set for the pump beam Refer to Chapter 5 Installation and Alignment Aligning the Opal Head and verify the Opal is correctly aligned to the Tsunami pump laser If it is refer to Opal Alignment for the optics set used 1 3 or 1 5 um and verify the correct optics are installed Opal fs Synchronously Pumped Optical Parametric Oscillator Symptom No flash when Scan Length is initiated Possible Causes Corrective Action Incorrect software parameters Verify the proper parameters have been selected in the Setup menu for the have been selected op
33. onto the center of high reflector M 11 Adjust M to send the reflected beam back through the center of iris Is a Place a white card with a small hole about 2 mm in it midway between Mg and M and position it so that the blue light from Mg passes through the hole Holding the card in place adjust M so that the reflected light from M passes back through the hole in the card b Remove the card Slightly close iris and observe the rear side of l4 Using small increments adjust M to center the reflected blue beam on the rear side of the iris Open the iris fully when completed 12 Place the white card in front of M so that the initial blue beam from M passes through the small hole Then adjust M to overlap the reflected blue beam from M on the hole in the card 13 Remove the white card 14 Slide the wave plate out of the pump beam 15 Verify the Tsunami laser is set to 810 nm with 2 W of average power and verify it is still mode locked 16 From the Setup menu if 1 3 1 6 is not displayed for the 1 5 um optics set select the optics set field then use the up down buttons to select 1 3 1 6 17 From the Setup menu if the pump input shown is not 810 select the pump beam field then use the up down buttons to select 810 18 From the Manual Control menu select the Temp field and set the crys tal temperature to 60 Please heed the caution warning in the Man ual Control Menu description Chapter 4 r
34. output power at the selected wavelength then use a monochromator to confirm the Tsu nami output wavelength 3 From the Manual Control menu set Loop to OFF C 1 Opal fs Synchronously Pumped Optical Parametric Oscillator 4 Usea monochromator to monitor the Signal wavelength and set its wavelength to the peak wavelength for the installed optic set 1 e 1 300 um or 1 500 um If necessary adjust the Opal cavity length via the motor position con trol in the Manual Control menu to set the Opal to 1 300 um for the 1 3 um set and 1 500 um for the 1 5 um set 5 Verify the Opal Signal beam is centered on output coupler M4 If required small adjustments can be made to M4 M and M to center the beam on l and M 6 Optimize the Opal Signal output power a Iterate between adjusting the vertical and horizontal controls on M and high reflector M or M p until maximum Signal output power is obtained b Again adjust the Opal cavity length via the motor position control in the Manual Control menu to return the Opal Signal to the appro priate wavelength 1 3 or 1 5 um 7 Repeat Steps 5 and 6 until the beam is centered on M it is optimized and it remains at the appropriate wavelength 8 Verify the Opal Signal beam is centered horizontally on the Servo Wavelength Monitor housing aperture If necessary reposition the servo housing which is secured to the base plate by two 20 in button head screws 9 From the
35. power followed by an adjustment of M and M 1 5 um configuration or M p 1 3 um configura tion for maximum output power Iterate your adjustment of M and M or M p until no further increase in power is possible Only then proceed to clean the next optic Before attempting to clean the crystal surfaces the electronics module must be turned off and the crystal allowed 5 minutes to cool to room temperature Failure to do so will damage the crystal Such damage is not covered by your warranty Clean all optics including the Brewster windows crystal surfaces prisms and beam splitter All mirrors are captured and held in place by a screw in holder Unscrew the holder and the mirror will come out with it Take care not to touch the optical surface The optic is retained by a small O ring and is removed by simply pulling it straight out of the holder In some cases you do not have to remove the optic from its holder to clean it Maintenance Each optical element has a v shaped arrow on its barrel This arrow points to the coated surface that faces the intracavity beam Also written on the barrel is the optic part number If you need to verify the location of the optic in the Opal refer to the part number list for each optic in Table 8 1 at the end of Chapter 8 Service and Repair If your Opal unit becomes misaligned refer to Chapter 5 Installation and Alignment for alignment procedures Standard Cleaning Procedur
36. put bezel using the longer 2 56 x 2 in cap screws supplied Slide the filter element under the clamping spring Completing the Alignment l Use the Manual Control menu to adjust the cavity length and crystal temperature for maximum output power Perform one adjustment at a time Adjust the focus of P to optimize the overlap of the pump beam with the cavity beam and thus maximize output power a Loosen the setscrew b Turn the translation screw on P slightly in one direction and note the change in output power c Ifit increased continue to turn until power starts to drop If it decreased turn the screw in the opposite direction When power is optimum lock the P setscrew then verify power remained optimum Replace the Opal cover Make sure you do not bump any control knobs From the Setup menu verify the operating parameters are correct i e the Tsunami pump wavelength and the Opal optics set is correctly selected then run the Scan Length command This will calibrate the wavelength and set the default crystal tempera ture to either the previously stored settings or to the factory pro grammed temperature offset 5 25 Opal fs Synchronously Pumped Optical Parametric Oscillator 5 From the Main menu adjust the output wavelength to 1 500 um using the up down keys 6 Use a monochromator to measure the output Signal wavelength If the wavelength readout differs from your actual measured wave length by
37. shutter lever is lowered to the closed position 2 3 Opal fs Synchronously Pumped Optical Parametric Oscillator Maintenance Required to Keep this Laser Product in Compliance with Center for Devices and Radio logical Health CDRH Regulations This section presents the maintenance required to keep this laser accessory product in compliance with CDRH Regulations This laser accessory product complies with Title 21 of the United States Code of Federal Regulations Chapter 1 Subchapter J Parts 1040 10 and 1040 11 as applicable To maintain compliance verify the operation of all features listed below either annually or whenever the product has been subjected to adverse environmental conditions e g fire flood mechanical shock spilled solvents This maintenance is to be performed by the user as outlined below 1 Verify removing the cover closes the shutter preventing the pump laser beam from entering the cavity 2 Verify that when the cover interlock is defeated the defeat mechanism is clearly visible and prevents installation of the cover until disen gaged 3 Verify all labels listed in Figure 2 4 Opal Radiation Control Drawing are present and firmly affixed 2 4 Laser Safet CE CDRH Radiation Control Drawing e WAVELENGTH OWER STABILIZED MONITOR MONITOR TO OPAL HEAD Je HEATER
38. the purge turn on procedure Purge Turn off Turn off the nitrogen supply at the tank then close the regulator valve on the Model 3910 purge unit This completes the purge turn off procedure The Front Panel Menu Control System The electronics module contains an LCD display and seven front panel but tons that allow you to select functions change values match the Opal cav ity to the Tsunami cavity scan over a wavelength range and otherwise control the Opal via a series of menus not unlike the hypertext help screens common to personal computer applications Seven major menu groups are used to control the Opal as listed below also refer to Figure 6 2 Each menu is described in detail later in this chapter The seven menu groups are e Main e Scan e Remote e Adjust Temperature e Setup system alignment e Configure system parameters e Diagnostics Each menu can have up to five soft buttons at the bottom of the screen which correspond to the five push buttons just below them These buttons allow you to monitor the system initiate setup and wavelength scans change parameters and run diagnostics When a soft button is absent from the display the associated push button is disabled for that menu screen 6 6 Operation When present the Next Field soft key allows you to toggle move the indi cator highlight box to place it around a field variable you wish to change power level crystal temperature wavelengt
39. to the servo wavelength monitor The beam splitter has an horizontal adjustment only Do not try to adjust it vertically Do not try to adjust the vertical control of the beam splitter Doing so will require a factory wavelength calibration 4 3 Opal fs Synchronously Pumped Optical Parametric Oscillator Servo wavelength monitor contains a stepper driven grating and a bi cell sensor Using microprocessor control this assembly monitors and sets the output wavelength by actively stabilizing the cavity length The error signal for cavity length stabilization is provided by ratioing the signals from each half of the bi cell The output wavelength is measured by deter mining the angle through which the grating rotates in order to maximize the integrated bi cell signal for the O order and 1 order diffracted beams Iris 1 is one of two irises in the cavity that facilitate in aligning the Opal It has a lever to set the iris size Do not move the mount from its factory set position or you will be unable to properly align the system Cavity fold mirror Mj directs the cavity beam from M to the center of cavity fold mirror M for the 1 5 um configuration or through the apex of prism Pr for the 1 3 um configuration M is also the PZT driven mirror The PZT is driven by the electronics module and actively stabilizes the cav ity length to maintain the synchronously pumped condition with the Tsu nami and thus keep the output w
40. 013 United States of America declare under sole responsibility that the OPAL cw Pulsed Optical Parametric Oscillator with Controller Manufactured after December 31 1996 meet the intent of Directive 89 336 EEC for Electromagnetic Compatibil ity Compliance was demonstrated Class A to the following specifications as listed in the official Journal of the European Communities EN 50081 2 1993 Emissions EN55011 Class A Radiated EN55011 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 hereby declare that the equipment specified above con forms to the above Directives and Standards Ae on Steve Sheng Vice President and General Manager Spectra Physics Inc Scientific and Industrial Lasers February 21 1997 Laser Safety EC Declaration of Conformity We Spectra Physics Inc Industrial and Scientific Lasers 1330 Terra Bella Avenue P O Box 7013 Mountain View CA 94039 7013 United States of America declare under sole responsibility that the OPAL cw Pulsed Optical Parametric Oscillator with 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 6082
41. 5 1 1993 Safety for Laser Products I the undersigned hereby declare that the equipment specified above conforms to the above Directives and Standards He on Steve Sheng Vice President and General Manager Spectra Physics Inc Scientific and Industrial Lasers February 21 1997 Opal fs Synchronously Pumped Optical Parametric Oscillator 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 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 American Conference of Governmental and Industrial Hygienists ACGIH 1330 Kemper Meadow Drive Cincinnati OH 45240 Tel 513 742 2020 Laser Institute of America 13501 Ingenuity Drive Suite 128 Orlando FL 32826 Tel 800 345 2737 Internet www laserinstitute org Compliance Engineering One Tech Drive Andover MA 01810 2452 Tel 310 445 4200 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 Industr
42. 775 2652 53 1 350 775 2390 42 1 400 810 2128 76 1 450 810 1832 69 1 500 810 1596 64 1 550 810 1327 61 1 600 810 1055 59 5 Optimize Tsunami output power for 2 W and mode lock the laser 6 Set the Opal for normal operation If the Opal is in idle mode i e Spectra Physics and its logo are dis played and the Main Menu soft key is available in the lower right hand corner return the Opal to normal operation by pressing the Main Menu soft key 7 Select the Setup menu and run Scan Length to establish oscillation and perform a quick calibration of the Opal As a general rule perform the initial scan at one of the high power wavelengths where there is minimal water vapor absorption e g for 1 3 um optics use 1 25 to 1 30 um and for the 1 5 um optics use 1 50 to 1 55 um 8 Use a monochromator to measure the Signal wavelength If the wave length shown on the Main menu is off by more than 3 nm when com pared to the measured value perform a wavelength recalibration according to the following a From the Diagnostic menu press Cal Wavelen to get to the Wave length Calibration sub menu b Select the Set actual wavelength field then use the up down push buttons to set it to the actual measured value Caution W DO NOT change the Zeroth Order at value c Run Scan Length from the Setup menu again d Measure the actual wavelength again If the wavelength shown is still off by more than 3
43. Assembly 1 Verify the Opal Signal beam is centered on output coupler M If required small adjustments can be made to M M and M to center the beam on l and M With the Signal beam centered on the output coupler the output beam should pass through the beam splitter and out the Signal output win dow Optimize the Opal Signal output power a Iterate between adjusting the vertical and horizontal controls on M and high reflector M until maximum Signal output power is obtained b In addition adjust the Opal cavity length via the motor position control in the Manual Control menu to maximize the Opal Signal output power Use an ir detector to verify the Opal Signal beam is centered horizon tally on the aperture hole of the Servo Wavelength Monitor Assembly Figure 5 2 If necessary reposition the servo housing which is secured to the base plate by two 4 20 button head screws destroy the factory wavelength calibration Caution n Do not use the Allen hex head adjustment of the beam splitter this will 5 16 Using an ir detector verify the Signal beam reflected from the front surface of the beam splitter is centered on the grating in the servo assembly The beam spot should be positioned on the grating as shown in Figure 5 7 In order to see the spot on the grating it may be necessary to man ually rotate the grating using the Manual Control menu refer to Chap ter 4 If the beam spot is not centered
44. Chapter 5 Installation and Alignment Converting from This completes the turn on sequence Turning Off the System To turn the system off simply 1 Set the Opal to idle mode from the Configure menu and leave the elec tronics on 2 Tum off the Tsunami and Millennia pump lasers Refer to their respec tive manuals This completes the turn off sequence 6 4 Operation Purging the Opal The Opal is sealed so that it can be purged with nitrogen gas Purging the cavity not only eliminates the typical problems associated with dust and contamination but also prevents tuning discontinuities caused by oxygen and water vapor Purging of the latter is imperative for operation between 1 33 and 1 48 um and when operating below 1 18 um Figure 6 1 The Model 3910 regulator filter purge unit provided with the Tsunami laser can be used to dry and filter bottled nitrogen gas for use in the Opal as well Because the wavelength regions that are affected by water vapor or oxy gen absorption are different for the Tsunami and Opal only one system requires purging at any one time To do this simply remove the purge line from the bezel connector of one system and plug it into the other However the two systems can easily share output from the Model 3910 by simply splicing the T connector provided into the output line and adding the sec ond line and connector also provided Information on connecting the Opal to this system is desc
45. IA 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 D 2 Replacing the PCMCIA Card Battery 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 every 2 years This completes the procedure for replacing batteries in the PCMCIA card D 3 Opal fs Synchronously Pumped Optical Parametric Oscillator D 4 Appendix E Scope Overview Using the Optional RS 232 IEEE 488 Interface This appendix explains how to operate the Opal system from a remote source using either the optional RS 232 serial interface or the IEEE 488 par allel interface the latter commonly referred to as the General Purpose Inter face Bus or GPIB The IEEE 488 parallel interface is based on the IEEE Standard Codes Formats Protocols and Common Commands specified in the ANSITEEE Standard 488 2 1987 The same commands are used whether you control the Opal using
46. Manual Control menu set the grating gtng wavelength for steps not wavelength using the Step um push button 10 Set the grating to the 0 order a Select gtng and use the up down push buttons to set it to about 9500 steps As the system moves toward this point and the 0 order is approached the power bar graph should begin to maximize b Atsome point the err bar will begin to move towards the center of the err bar display When this happens stop pressing the button so that the err bar remains in the center The power graph should be at about the 5096 mark Record the gtng step number displayed 11 Set the grating to the 1 order Use the down push button to lower the grating number to the point where the power bar graph maximizes and the err bar once again cen ters 12 Use the black knob on the beam splitter to adjust it horizontally to maximize the power bar graph Caution Do not use the Allen hex head adjustment of the beam splitter because this will destroy the factory wavelength calibration 13 Repeat Steps 10 through 12 until the power bar graph is maximized 14 Turn on the Loop C 2 Servo Wavelength Monitor Calibration 15 Press the Back key to exit the Manual Control menu 16 From the Diagnostics menu select Cal Wavelng 17 Measure the actual operating wavelength of the Opal Signal output beam with the monochromator then select the Set Actual Wavelength field and use the up down push buttons to
47. Monitor Signal Cable TTL Signal Cable Figure 4 4 Rear Panel Opal Electronics Module Voltage Selector Switch provides selection between 115 and 220 Vac Verify this switch is set to the proper position before turning on your system the first time If not properly set damage may occur to the elec tronics module and crystal heater Such damage is not covered by your warranty Warning W Use the following fuse values when you set the Opal electronics for your line voltage 4 6 Line Voltage Fuse Value 100 to 120 Vac 220 to 240 Vac 1 A slow blow 1 2 A slow blow WAVELENGTH STABILIZED connector BNC provides a TTL level sig nal to indicate that the wavelength selected has stabilized A high level sig nal indicates stable output a low level signal indicates an unstable signal PZT MONITOR connector BNC provides a buffered signal from the PZT driver circuit that can be used to determine intra loop activity Controls Indicators and Connections POWER MONITOR connector BNC provides a buffered signal from the output power monitoring circuit that can be used to monitor the Opal out put power level TO OPAL HEAD connector D Sub provides connection for drive and feedback signal cable that attaches to the output bezel of the Opal head HEATER connector provides connection for the heater drive and feed back cable that attaches to the output bezel of the Opal head The heater provid
48. Opal Alignment 1 5 um Optic Set Aligning the Opal Cavity earlier in this chapter However do not perform the final step to adjust the focus of P This completes the conversion to the 1 5 um optics set 5 27 Opal fs Synchronously Pumped Optical Parametric Oscillator Converting from 1 5 to 1 3 uim The following procedure allows you to change optics sets from 1 5 um to 1 3 um operation 1 Close the Opal shutter 2 Remove mirrors M through M and place them in their protective stor age containers 3 Install the 1 3 um optics listed in Table 5 4 into Opal However instead of putting the output coupler into M install the additional high reflec tor provided in the optics kit This aids in alignment later Table 5 4 Optics List for 1 3 um Operation Optical Position Part Number Output Coupler M G0324 022 High Reflectors M Mz Mg M Mzp G0380 001 High Reflector Mao G0380 003 If not available in your kit use G0380 001 High Reflectors M5 M G0079 020 High Reflector M5 with PZT Assy 0449 1840 4 Setthe Tsunami pump laser to 830 nm at 2 W and verify that it is mode locked 5 Open the Opal shutter Place the Opal wave plate into the Tsunami pump beam and rotate the wave plate to rotate the pump beam polarization 90 90 rotation 1s achieved when the reflection of the Tsunami beam from the front surface of the crystal exhibits an intensity minimum 7 Align the Opal cavity according to the proced
49. Opal Femtosecond Synchronously Pumped Optical Parametric Oscillator SPPO User s Manual GS Spectra Physics The Solid State Laser Company 1335 Terra Bella Road Mountain View CA 94043 Part Number 0000 234A Rev E September 2001 Preface This manual contains information you need to safely install align operate maintain and service your Opal femtosecond synchronously pumped optical parametric oscillator SPPO The introductory chapter contains a brief description of the Opal and where it fits in with the Tsunami family of products The Opal is designed for use with the Tsunami mode locked Ti sapphire laser pumped by a Millen nia Xs solid state laser or argon ion laser These are Class IV lasers and they as well as the Opal emit laser radiation that can permanently damage eyes and skin The Laser Safety section contains information about these hazards and offers suggestions on how to safeguard against them To mini mize the risk of injury or expensive repairs read this chapter and carefully follow these instructions Opal Description contains a discussion of synchronously pumped optical parametric oscillators and it provides a detailed description of the Opal It concludes with system specifications and outline drawings The middle chapters describe the Opal controls indicators and connec tions and guide you through its setup and installation alignment and oper ation The last part of the manual cove
50. PAL HEAD connector on the elec tronics module rear panel 5 Attach the power cord to the electronics rear panel and verify the sys tem is set for your line voltage Also verify the correct fuse is installed Refer to Appendix A Setting the Line Voltage Switch for informa tion on selecting and setting both these items Use the following fuse values when you set the Opal electronics for your line voltage Line Voltage Fuse Value 100 to 120 Vac 1A slow blow 220 to 240 Vac Ve A slow blow 6 Connect the power cord to your power source Millennia Diode Pumped Laser Tsunami Mode Locked Opal Optical Ti sapphire Laser Parametric Oscillator Figure 5 1 Opal system layout with a Tsunami Mode Locked Ti sap phire Laser and a Millennia Diode Pumped Pump Laser Installation and Alignment Removing Installing the LBO Crystal Warning y Skip this section if the crystal is already installed but please read the warn ing statement below about safeguarding your expensive crystal from mois ture damage Due to the hygroscopic nature of the LBO crystal you must keep the crystal contained in a dry environment at all times and minimize the exposure time to the environment even during installation Install the crystal and turn on the Opal electronics immediately to bring the crystal temperature above ambient then leave the electronics on with the crys tal temperature set at
51. RR Hollow Retro reflector Xtal Non linear Crystal PMT Photomultiplier Tube Figure B 3 The Model 409 08 Autocorrelator Optical Path The beam paths are displaced by HRR and HRR in and out of the plane of the paper so the configuration corresponds to the background free method shown in Figure B 2 B 3 Opal fs Synchronously Pumped Optical Parametric Oscillator Signal Interpretation In order to determine the actual pulse width from the displayed autocorre lation function it is necessary to make an assumption about the pulse shape Table B 1 shows the relationship between pulse width Ar and the autocorrelation function Af for several pulse shapes It also shows the time bandwidth product Atp Av for transform limited pulses Table B 1 Second Order Autocorrelation Functions and Time Bandwidth Products for Various Pulse Shape Models Function I t At Atac AtjAn Square 1 lt 4 2 1 1 0 t 2t 2 Diffraction Function I t sin H at 0 751 0 886 At Gaussian Hyperbolic Secant Lorentzian Symmetric two sided exponential oS ll t exp tini 2 0 707 0 441 p p t 1 0 500 0 221 1 4t At exp In2 t 0 413 0 142 At p At sec is FWHM of intensity envelope of the pulse Atyc sec is FWHM of autocorrelator function of the pulse Tat Hertz is FWHM of the spectrum of the pulse GVD Compensation in Measurement of Ultrashort Pulses B 4 B
52. S All clear all offsets in this tics set oj Point clear only the offset at this wavelength Next Field Full Scan Align Length Scan Length Clear Back Main All Ploint Cal Wavelength Preparing to scan length Desired xtal temp is 64 4 Actual temp is 47 9 Wavelength Calibration Set actual wavelength Then press Set Cal key Zeroth Order at 9559 SCANNING COARSE LENGTH Scanning reverse Scan was not successful Try full alignment Was scan successful any key to continue Figure 6 2 Flowchart of the Opal electronics module menu system 6 8 Operation Main Menu MAIN Scan Remote Adj Setup Config Ctrl Temp The Main menu is at the top of the menu structure and is displayed at start up immediately following the Spectra Physics logo It is the default screen for monitoring the system It continuously displays Signal output power the relative position of the PZT within its range the Signal and Idler wave length and whether or not the servo is on and if the system is locked From this menu you can reach all the other system functions The Power bar graph on the left of the screen shows Signal output power The position of the PZT relative to its full range as shown in the PZT bar graph indicates how well the servo is tracking When the system is operat ing correctly the small bar moves very slightly about the center position The selected wavelength for the Signal
53. a flash is still not observed refer to the troubleshoot ing guide in Chapter 8 or call your Spectra Physics service repre sentative 6 Once you observe the flash translate M slightly so you get sustained lasing action Place a power meter in front of the Signal output window Translate M slightly back and forth until you find the point for maxi mum output power 9 Ensure the Tsunami laser is operating at 810 nm and repeat Steps 6 and 8 to maximize output power 10 Maximize output power again by iterating horizontal and vertical adjustments of M and M 11 Use an autocorrelator such as the Model 409 08 to monitor the out put pulse width Aligning the Beam to the Servo Wavelength Monitor 1 Verify the Opal Signal beam is centered on output coupler M If required small adjustments can be made to M M and M to center the beam on l and M With the Signal beam centered on the output coupler the output beam should pass through the beam splitter and out the Signal output win dow 2 Optimize the Opal Signal output power a Iterate between adjusting the vertical and horizontal controls on M and high reflector M until maximum Signal output power is obtained b In addition adjust the Opal cavity length via the motor position control in the Manual Control menu to maximize the Opal Signal output power 3 Use an ir detector to verify the Opal Signal beam is centered horizon tally on the aperture hole o
54. aci n directa daarvan Klas IV laser onnement direct ou diffus Leistung Wellenl nge und como a la dispersa Pro produkt Vermogen Laser de Classe 4 Puis Pulsbreite sind abh ngig ducto laser clase 4 Poten golflengte en pulsduur sance et longueurs D onde von Pumpquelle und cia longitud de onda y afhankelijk van pomp dependant de la configura Laserkonfiguration anchura de pulso opties en laser konfigu tion et de la puissance de Bedienungsanleitung dependen de las opciones ratie pompe beachten de bombeo y de la configu racion del laser Battery Remplacer la pile par le Batterie nur durch gleichen Reemplazar la bater a con Vervang batteryen door de Replace m me mod le ou un oder baugleichen Typ el mismo tipo o equiva zelfde of door de fabrikant ment Label mod le quivalent Se gem Herstellerangaben lente recomendado por el geadviseerde equivalente 10 d barasser des piles usag es conform ment au recommandations du fabri cant ersetzen Verbrauchyte Batterien ordnungsgem entsorgen fabricante Peligro Deshacerse de las bate r as usadas de acuerdo con las instrucciones del fabricante typen Voer de gebruikte battereien af volgens de instructies van de fabri kant 2 7 Opal fs Synchronously Pumped Optical Parametric Oscillator CE Declaration of Conformity We Spectra Physics Inc Scientific and Industrial Systems 1330 Terra Bella Avenue P O Box 7013 Mountain View CA 94039 7
55. all hole in it allows part of it to pass through Adjust M horizontally and vertically to reflect this pump beam back through the hole in the card Remove the card and scan M as you did before and look for a flash a If you do not observe a flash replace the output coupler with the high reflector then reoptimize the cavity for maximum intracavity visible light generation To do this adjust M and M7p and make small translational adjustments of M with the motor control b When intracavity visible light is maximized repeat Steps 2 through 6 If a flash is still not observed refer to the troubleshoot ing guide in Chapter 8 or call your Spectra Physics service repre sentative 5 15 Opal fs Synchronously Pumped Optical Parametric Oscillator 10 11 12 Once you observe the flash translate M slightly so you get sustained oscillation Place a power meter in front of the Signal output window Translate M slightly back and forth until you find the point for maxi mum output power Ensure the Tsunami laser is operating at 775 nm and repeat Steps 7 and 9 to maximize output power Maximize output power again by iterating horizontal and vertical adjustments of M and M p Using an autocorrelator such as the Model 409 08 to monitor the pulse use the micrometer adjust on Pr to optimize pulse width and re optimize output power as needed using Steps 9 and 11 Aligning the Beam to the Servo Wavelength Monitor
56. als including a plastic hemostat tweezers and optical grade lens tissue e atee fitting and gas tubing for purging the Opal e infrared ir detector card e a filter for a Spectra Physics Model 409 08 autocorrelator that allows measurement of the signal pulse width 1 1 1 6 um In separate containers you will find e the Opal electronics module with an accessory kit containing connect ing cables e an Optics kit if a second set was ordered at the time you purchased your Opal xvii Chapter 1 The Opal SPPO Introduction Optical parametric oscillators OPOs were first used in the mid 1960 s as an alternative to dye lasers for generating coherent radiation tunable over a wide wavelength region It is only recently however that they have become a practical reality with the advent of new high quality nonlinear optical materials and high power mode locked pump sources Opalis the first femtosecond synchronously pumped optical parametric oscillator SPPO with the following features e Ti sapphire pumped Temperature tuned e Fully automated cavity length adjustment with active stabilization e Automated wavelength scanning and setup Output power gt 150 mW at 1 3 um and 1 5 um e Output pulse width lt 130 fs e Synchronized Signal and Idler outputs with wavelength coverage from 1 1 to 2 6 um The Opal extends the ease and convenience of your Tsunami Ti sapphire laser to an entirely new infrared wavelength ran
57. am but does not stop the lasing action i e it is partially in the beam A portion of the intracavity beam will be directed onto Mgp 3 Place the ir detector card provided in the accessory kit in front of M p to observe the 1 3 um beam and adjust Mg vertically and horizon tally to direct the beam through Pr and onto the center of M p You will see a line of light on the detector card and within that line you will see a spot that appears more intense Position this spot in the center of M p 4 Place the ir detector card 5 cm from Pr so the beam from Pr passes through a 2 mm hole in the card 5 To align M to the rest of the cavity direct the reflected beam from M p back through the hole in the card using the vertical and horizontal con trols on Mg 6 Using the micrometer on Pr insert the prism into the beam until the beam is fully bisected a First the main cavity prism free cavity oscillation will stop then as you insert more glass in the beam path oscillation will start in Installation and Alignment the secondary cavity Continue to insert Pr until a visible flash is observed then optimize Pr for sustained lasing action b Ifthe Opal fails to flash in Step a repeat Steps 4 and 5 Note verti cal alignment is easily verified by noting the position of the hori zontal line on the card c Horizontal positioning is more difficult It might be necessary to try several small turns 1 8 of a revolution of th
58. as a translation screw for moving the crystal horizontal to the beam to optimize conversion efficiency and a setscrew to lock it in the selected location Cavity mirror M focuses the cavity beam into the crystal then directs it back onto cavity focus mirror M It also directs the cavity beam onto the center of cavity mirror M It has vertical and horizontal controls for steer ing the cavity beam and a translation control for focusing the cavity beam in the crystal A setscrew locks the translation dovetail stage in place Cavity mirror M directs the cavity beam from M through iris l through the center of output coupler M and out the Signal output window It has vertical and horizontal adjustments Iris 1 is one of two irises in the cavity to facilitate in aligning the Opal It has a lever to set the iris size Do not move the mount from its factory set position or you will be unable to properly align the system Output coupler OC M is one of two cavity end mirrors Whereas the high reflector reflects all light back into the cavity the output coupler allows a small percentage to pass through as the output beam M is a motor driven mount that provides servo driven coarse adjustment of the cavity length Vertical and horizontal controls allow adjustment for opti mized output power and mode quality These controls are accessible when the cover is in place Beam splitter picks off a small amount of the beam and directs it
59. as shown a Usethe black adjustment knob on the beam splitter to center it hor izontally Installation and Alignment b Center the beam vertically by making very small adjustments to Ms M5 and M Do not lose oscillation use the Manual Control menu to adjust the position of M for maximum output power after each incremental adjustment Beam Post Grating Figure 5 7 Positioning the Signal beam horizontally on the grating 5 Verify any visible light contained in the output beam is blocked by the filter attached to the Signal output Brewster window Figure 5 8 The filter is shipped in the accessory kit and must be installed before the Opal can be used the first time Remove the two 2 56 x 4 in cap screws securing the Signal Brewster window to the Opal head and install the filter assembly along with the window assembly to the out put bezel using the longer 2 56 x 42 in cap screws supplied Slide the filter element under the clamping spring Mounting Screws 2 Spring Filter Figure 5 8 Visible Light Filter Side View Attaches to Signal Window Completing the Alignment l Use the Manual Control menu to adjust the cavity length and crystal temperature for maximum output power Perform one adjustment at a time Adjust the focus of P to optimize the overlap of the pump beam with the cavity beam and thus maximize output power a Unlock the setscrew b Turn the translation screw on P
60. asterisk points New offset values become associated with the selected Signal wavelength displayed in the window and are used by the system until either the entire offset table is cleared using the Clear All soft button under Clear Offsets a single point s is are cleared using the Clear Point soft button or the system is turned off Use the Save Recall feature in the Configuration menu to save these values in a user defined table for later use Up to seven different user defined tables can be saved and recalled in this manner along with three system preset tables figure menu the user modified offset table will be unrecoverable once the Clear All soft button is pushed under the Clear menu or the unit is turned off To restore the table if it was not saved requires the operator to re enter every offset one at a time Caution W If the table has not been saved using the Save Recall function in the Con To set an offset first select the wavelength by selecting the Signal field using the Next Field soft button A box surrounds the field when it is selected Change to the wavelength of choice using the up down buttons Next select the offset field then select the Single Point Offset or Temp Table Shift function by pressing the Shift Point soft button Change the offset per cent via the up down buttons Any increase or decrease in power resulting from a change in crystal temperature is shown in the Power bar graph Note that it is
61. ator a From the Setup menu initiate a Scan Length command This ensures the software recognizes the polarity of the motor b Set M to the center of its range Use the Manual Control menu and the up down push buttons on the electronics module to set Motor to a 5096 value Refer to Chap ter 6 for the menu flow chart and menu descriptions c Using a metric scale measure the spacing between the front face of each tilt plate not the mirror itself for mirrors M M M Ms M3 M M Ms Mg Mg and M M d Add the total distances Add 98 mm to the total distance The 98 mm compensates for the fact that the mirrors are recessed from the front face of each mount It also includes the double pass distance of the fold mirrors f Subtract the total measured distance of the Opal cavity length from that of the Tsunami laser 1 e find the difference between the two g Loosen the two large Allen hex screws that secure the M mount to the base plate of the Opal and slide the mount to the point where the Opal cavity length matches that of the Tsunami If required move the entire M mount to another set of mounting holes in the base plate The holes are 2 54 cm apart Aligning the Pump Beam Warning To prevent damage to the crystal during this procedure reduce Tsunami W power to minimum while aligning the pump beam Do not allow the focused beam from P to make contact with the temperature sensor on the side of the
62. avelength fixed M has vertical and horizontal adjustments Cavity fold mirror Mg directs the cavity beam from M to the center of the high reflector M It is always used in the 1 5 um configuration but only for initial alignment with the 1 3 um optics Mg has vertical and hori zontal adjustments High reflector HR M is the high reflector cavity end mirror for the 1 5 um configuration It is used only for initial alignment with the 1 3 um optics set Its vertical and horizontal adjustments allow optimization of out put power and mode quality These controls are accessible when the cover is in place via a cutout in the cover Cavity fold mirror Mgp directs the cavity beam from Pr to Pro It is employed only in the 1 3 um configuration Mgp has vertical and horizontal adjustments High reflector HR M p is the high reflector cavity end mirror for the 1 3 um configuration Its vertical and horizontal adjustments allow you to optimize output power and mode quality These controls are accessible when the cover is in place Prisms Pr and Pr control overall group velocity dispersion GVD of the cavity to provide the shortest stable output pulse when the 1 3 um optics set is installed Micrometer controls on each mount move the prisms in and out of the intracavity beam For 1 5 um operation the prisms are not used and Pr is moved completely out of the beam path When used Pr directs the cavity beam from M to Mgp and Pr
63. ble Query Reads the Event Status Enable ESE register See ESE xxx above RESPONSE DATA format This means that values are ASCII strings like Note g This and all other registers are read written using the lt NR1 NUMERIC 0 and 255 not single bytes like 0x00 hex or OxFF hex ESR cn Standard Event Status Register Query Reads and clears the Event Status Register ESR Bits are defined as fol lows Bit Definition 7 PWRON Power On Set when the electronics module power is first turned on Will read 1 the first time 0 on subsequent queries 6 URQ User Request always 0 5 CMDERR command error The Opal couldn t interpret the command E 4 Using the Optional RS 232 IEEE 488 Interface 4 EXEERR Execution error The Opal could not execute the command For example it cannot recall a setup which does not exist or go to an out of range wave length DEVERR device error always 0 QRYERR query error always 0 RQSCTNL request control always 0 OPCMPL operation complete set by OPC O N Q Bits in the ESR are set by events They are cleared only by reading the ESR with the ESR query For example if an invalid command is followed by a valid one the CMDERR bit will remain set IDN cR Identification Query Returns an identification string such as Spectra Physics Opal 0 2 23 1rF The last number is the software revision level OPC
64. ble in the nonlinear crystal when the pump pulse is present for fs OPOs it is neces sary to use a synchronous pumping scheme i e match the cavity length of JJ Description the OPO to that of the Ti sapphire pump laser so that the signal and pump pulses are always present in the nonlinear crystal at the same time The pioneering work on fs SPPOs systems was done at Cornell University in the laboratory of Professor C L Tang using angle tuned potassium tita nyl phosphate KTP as the nonlinear gain medium More recently other groups have demonstrated Ti sapphire pumped SPPOs The Opal Spectra Physics developed the Opal a commercial fs SPPO designed to be pumped by the Tsunami mode locked Ti sapphire laser Figure 3 3 shows a typical setup Idler Opal Tsunami Millennia Signal Optional Residual Pump Beam Output Figure 3 3 Typical System Setup The Opal uses a 90 non critically phased matched temperature tuned lithium triborate LBO nonlinear crystal as its gain medium Although LBO has a lower nonlinear coefficient than other materials it offers several advantages 1 non critical phase matching means a collinear pump and signal geometry that facilitates the initial alignment procedure 11 there is no spatial walk off of the pump and signal beams which favors a longer interaction length and higher gain iii LBO exhibits lower group velocity mismatch 1
65. cards 2 2 ete D 1 Table of Contents List of Tables Table 2 1 Label Translations ooir ie m 2 7 Table 3 1 Opal Specifications aaa 3 8 Table 5 1 Typical Settings for Opal Output at 1 300 UM 1 2 ee 5 18 Table 5 2 Typical Settings for Opal Output at 1 500 um nonas ee 5 26 Table 5 3 Optical List for 1 5 um Operation eee 5 27 Table 5 4 Optics List for 1 3 um Operation eee 5 28 Table 6 1 Typical Settings for Several Opal Wavelengths cece eee eee 6 3 Table 8 1 Opal Standard Mirrors ern 8 6 Table 8 2 Opal Hardware 1 2 0 0 ccc nee eae 8 6 Table 8 3 Tsunami Special Optics aaea 8 6 Table A 1 Fuse Selection 0 0 0 00 ccc eta A 2 Table B 1 Second Order Autocorrelation Functions and Time Bandwidth Products for Various Pulse Shape Models 2 2 tte B 4 Table B 2 Positive Dispersion Values 800mm 1 1 0 cette eee B 6 Table B 3 Negative Dispersion Values 9 800mm 2 2 eee B 6 Table C 1 13 Order Settings for Several Opal Wavelengths 000 0c cece eee eee C 3 Table E 1 RS 232 C Interface to a Standard 25 pin PC Com Port 0000 e eee eee E 6 Table E 2 RS 232 C Interface to a Standard 9 pin PC AT Com Port aaa E 6 xi Opal fs Synchronously Pumped Optical Parametric Oscillator xii Danger Laser Radiation Danger Danger Warning Warning ESD Caution Note Do
66. chronously Pumped Optical Parametric Oscillator b Ifa flash is observed move M back to the position that produced it and skip to Step 20 c Ifno flash is observed by the time M has reached the end of its travel translate it in the other direction until a flash is observed At that time move M back to the position that produced it and skip to Step 20 d If the Opal fails to flash in either direction re measure the cavity length as outlined under Initial Set up above then repeat the entire alignment Steps Ithrough 19 If still no flash is observed refer to the troubleshooting guide in Chap ter 8 or call your Spectra Physics service representative 20 Adjust M and M horizontally and vertically to optimize light intensity A well aligned cavity produces a small amount of green light mixed with the reddish orange light most visible at M5 Alignment of Pr and Pr Prism Sequence Warning s When performing the procedure below do not change the location of M p i e do not loosen its mounting screws The position of this mirror assembly is permanently set at the factory and changing it might require a service call to relocate it Such a call is not covered under your war ranty 1 Adjust the micrometer of Pr to position the translation stage in the center of its range Pr will be used later to optimize pulse width 2 Adjustthe micrometer of Pr until the prism begins to intersect the int racavity be
67. compensation control to adjust Tsunami prisms Pr2 laser and Pr to eliminate cw breakthrough Refer to Appendix B in the Tsunami users manual for information on cw breakthrough 8 5 Opal fs Synchronously Pumped Optical Parametric Oscillator Replacement Parts Table 8 1 Opal Standard Mirrors Description Location Coating Range Part Number Beam splitter Assembly High Reflector PZT Assembly High Reflector PZT Assembly Crystal Mirror Fold Mirror Fold Mirror Output 996 Mirror Output 696 Mirror High Reflector Mirror High Reflector Mirror High Reflector Filter Signal Output 1 3 1 5 um 1090 1370 nm 1320 1600 nm Uncoated cut to Brewster s angle 1090 1370 nm 1320 1610 nm 1090 1370 nm 1320 1620 nm 1090 1370 nm 1320 1620 nm 1090 1365 nm 1 2 um passband G0020 000 0449 1840 0449 1850 0449 9200S G0079 020 G0079 021 G0324 022 G0324 023 G0380 001 G0380 002 G0380 003 G0385 000 Table 8 2 Opal Hardware Description Part Number This Opal User s Manual Assembly Brewster window Purge tubing kit Assembly Idler 1 Assembly Idler 2 Motor micrometer Opal software rev 2 21 PCMCIA card 0000 234A 0441 8110S 0447 1590 0450 2210 0450 2220 5401 1579 0450 7870 Table 8 3 Tsunami Special Optics Description Part Number Birefringent filter single plate Mirror Output Coupler 0434 8931 G0381 001 Chapter 9 Warranty Cus
68. crystal or its bonding agent or the heater cooling unit below the crystal Even a low power focused beam may cause damage and or deposit a film onto the crystal face Also the differential temper ature resulting from focusing the beam near the crystal edges can cause the crystal to fracture Crystal damage due to the above is not covered by your warranty Use an ir viewer to align the pump beam 1 Set the Tsunami pump power to minimum 2 Open the Opal shutter and verify the Tsunami pump beam is centered on P If the beam is not centered on P refer to Aligning the Opal Head earlier in this chapter for instructions 3 Adjust P horizontally and vertically to direct the pump beam onto the center of P 4 Adjust P horizontally and vertically to direct the pump beam through the center of iris and onto the center of P4 5 20 Installation and Alignment 10 Aligning the Opal Cavity 1 Close the iris a little to verify the beam is centered Note the even ring around the opening when it is centered If necessary repeat these last steps starting at Step 3 until this condition is achieved Adjust P horizontally and vertically to direct the pump beam onto the center of P Adjust P to direct the pump beam through M and through the crystal so that it strikes the center of Mg If necessary repeat Steps Sand 6 until the pump beam goes through M the crystal and is centered on M It may take several iterati
69. d if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense Modifications to the laser system not expressly approved by Spectra Physics could void your right to operate the equipment Table of Contents PrelaCe Lt LE ERES LLLI I iii Environmental Specifications cece eee V Warning Conventions 24 0 60 cocus xenon ee ee ke ek ee he xiii Standard Units cde 13 kA DUA AND os A HORE EDNA Ka dice PRORA dale deb XV Unpacking and Inspection 2 0c cee es xvii Chapter 1 Introduction 24 2 Hamak rk ERE IRI IRE eme LEER ARYA 1 1 WOOD SPPO det stem oma feel D DA p fci inl PAM Sad NG Ede 14 Patents c an na an Hainan Dalan Dhel Ng nan pap ADAN Seegk qiesnrdqR ied 1 2 Configurations spa KAG Uie Quee oath nagan TG eh dem ENS Gare Dena Ead 1 3 Chapter 2 Laser Safety ia ania a ka va ka Ry ROO ERIKA NAKA KAANAK 2 1 Precautions for the Safe Operation of Class IV High Power Lasers and Accessories 2 1 SCHADE 2 3 Shutter Interlock 2 0 ee eee 2 3 Maintenance Required to Keep this Laser Product in Compliance with Center for Devices and Radiological Health CDRH Regulations 0 000 c eee eee 2 4 CE CDRH Radiation Control Drawings ills 2 5 Label Translations i
70. d its progress is displayed Soft Keys Abort stops the scan and returns control to the Setup menu Scanning Coarse Length Menu SETUP SCANNING COARSE LENGTH Scanning reverse Cr The Scanning Coarse Length menu reports to the Scan Length menu It dynamically displays a scan search for the Tsunami Opal cavity match point i e the point where the Opal cavity matches that of the Tsunami laser or where the round trip time of the signal wavelength in the Opal cav ity matches that of the pump wavelength in the Tsunami If the scan is successful i e the Opal flashes and oscillates the scan stops immediately and the grating bi cell servo system is automatically cali brated It calibrates the grating in the servo housing for the 0 order refer ence point and for the 1 order beam position based on the wavelength chosen It then returns control to the Main menu If the scan was not successful a prompt is displayed requesting a full align ment be performed Control is returned to the Setup menu Soft Keys Abort Scan stops the scan and immediately returns control to either the Setup menu or the Manual Control menu Operation Configure Menu CONFIGURE CONFIGURE Save Misc Diag Goto Main Recal nostics Idle menu The Configure menu reports to the Main menu and allows the operator to save and recall system settings run Opal diagnostics and set the Opal to Idle for overnight stand by mode Soft Keys
71. d to comply with the limits for a Class A digital device pursuant to Part 15 of the FCC Rules 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 Thank you for your purchase of Spectra Physics instruments 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 Plug Outlet and Socket Couplers for Indus trial Uses listed in the official Journal of the European Communities Environmental Specifications FCC Regulations 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 8096 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 This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to Part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment This equip ment generates uses and can radiate radio frequency energy an
72. dilutes contamination to the limit set by solvent impurities solvents must be as pure as possible Use solvents spar ingly and leave as little on the surface as possible As any solvent evap orates it leaves impurities behind in proportion to its volume Store all solvents in small glass bottles Solvents collect moisture during prolonged exposure to air Avoid stor ing solvents in bottles where a large volume of air is trapped above the solvent 7 3 Opal fs Synchronously Pumped Optical Parametric Oscillator e Use Kodak Lens Cleaning Paper or equivalent photographic clean ing tissue to clean optics e Use each piece of lens tissue only once dirty tissue merely redistrib utes contamination it does not remove it Caution Do not use lens tissue designated for cleaning eye glasses Such tissue IN M contains silicones These molecules bind themselves to the optic coat ings and can cause permanent damage Also do not use cotton swabs e g Q Tips Solvents dissolve the glue used to fasten the cotton to the stick resulting in contaminated coatings Only use photographic lens tissue to clean optical components General Procedure for Cleaning all Optics Except the Crystal Refer to General Procedures for Cleaning the Crystal later in this Warning W DO NOT USE THESE INSTRUCTIONS FOR CLEANING THE CRYSTAL chapter With the exception of the prisms and Brewster windows all optics must be removed
73. directs the cavity beam from Mg to high reflector M p Pr is used to optimize pulse width by varying the amount of glass inserted into the cavity Idler focus mirror Idler collimates the Idler and residual Ti sapphire beams passing through focus mirror M and directs it toward Idler mirror ldler It has vertical and horizontal adjustments Idler mirror Idler directs the Idler and residual Ti sapphire beams out the Idler output window It has vertical and horizontal adjustments 4 4 Controls Indicators and Connections Residual pump mirror RPM directs the residual Ti sapphire pump beam reflected from the input surface of the LBO crystal through the focus ing lens and out the Residual Pump Port Output window It has vertical and horizontal adjustments When absent a beam block contains the residual beam Residual pump beam focusing lens RPB lens recollimates the residual pump beam as it passes out the Residual Pump Port Output window To focus the beam the lens is moved by loosening the Allen screw and manu ally moving the mount Opal Electronics Module Front Panel Figure 4 3 shows the location of the various controls and indicators on the Opal electronics module front panel S Speetra Physies E E V usu JI LCD Display Soft Keys Up Down Push Buttons Figure 4 3 Front Panel Opal Electronics
74. djust P horizontally and vertically to direct the pump beam onto the center of P 4 Adjust P horizontally and vertically to direct the pump beam through the center of iris and onto the center of P Close the iris a little to verify the beam is centered Note the even ring around the opening when it is centered If necessary repeat these last steps starting at Step 3 until this condition is achieved 5 Adjust P horizontally and vertically to direct the pump beam onto the center of P 6 Adjust P to direct the pump beam through M and through the crystal so that it strikes the center of Ms If necessary repeat Steps 5 and 6 until the pump beam goes through the crystal and is centered on the intracavity surfaces of Ms and M It may take several iterations of adjusting P and P3 and repositioning the pump beam to accomplish this 7 Observe the beam entering the crystal If you observe a bright spot on the surface of the crystal a high scattering site due to a surface flaw or burn translate the crystal slightly to an area that produces the least Opal fs Synchronously Pumped Optical Parametric Oscillator amount of reflectance The beam should be close to the center of the crystal Do not move the beam near the edge of the crystal a Loosen the setscrew that locks the translation stage in place just enough so that the stage can be translated If loosened too much the stage becomes loose on the dove tail and alignment wil
75. e horizontal control to obtain horizontal alignment After each adjustment translate Pr through its range and look for the flash If after several attempts the Opal fails to flash return Pr to the point where the main cavity oscillates then repeat this procedure starting at Step 2 Completing the Cavity Alignment Warning Y Adjust M p to optimize intracavity visible light generation Close the shutter and replace the high reflector in M with the appropri ate output coupler for the 1 3 um wavelength The 3 point registry in the optics holder ensures good resetability of the optic Screw the optic holder in finger tight but do not over tighten Open the shutter and readjust M vertically and horizontally slightly to re establish lasing Do not screw the optic holder too tight Over tightening will at mini mum distort the optic and at worst chip it and possibly render it use less Tighten only until slight resistance is felt If the Opal oscillates again skip to Step 8 If it fails to oscillate oF Translate M back and forth slightly using the Manual Control menu as you did before and look for a flash on an ir detector card placed out side the Signal window Total translation should be no more than 1 mm If the Opal begins oscillating skip to Step 8 If it fails to oscillate 4 Place the ir detector card midway between M and M so it detects a small amount of the pump beam reflected from M and so the sm
76. e length stabilization for synchronization with external rf sources or other mode locked laser sources However many applications require access to wavelengths that are not directly covered by the fundamental Ti sapphire output or through har monic generation Wavelength extension has generally been accomplished through two approaches i amplification with white light continuum gen eration and or optical parametric amplification and ii a synchronously pumped optical parametric oscillator SPPO The former provides higher energies at lower repetition rates typically uJ mJ at kHz repetition rates while the latter provides nJ pulse energies at repetition rates of about 80 MHz The SPPO offers inherent synchronization at multiple wavelengths useful for fs pump probe measurements and generally lower amplitude noise than that obtained from an amplified system The optical parametric oscillator OPO shown in Figure 3 1 operates on a very different principle than that of a laser A laser derives its gain from spontaneous and stimulated emission generated by transitions between dif ferent atomic or molecular states These transitions have inherent line widths that govern the maximum tuning range of the laser e g a dye laser tunes over a range of 30 40 nm per dye while a Ti sapphire laser tunes over a 300 nm range In contrast an OPO derives its gain from a nonlinear frequency conversion process which can provide wavelength tunabil
77. ecause the pulses produced by the Tsunami laser and the Opal are extremely short 130 fs pulse broadening in optical materials from group velocity dispersion or GVD makes true pulse width measurement difficult Also because the GVD of glass causes the pulse width to broaden the pulse reaching an experimental sample after traveling through beam splitters lenses etc may not be the same pulse that is measured by the autocorrelator It is thus important to ensure that the measurement tech nique and the experimental incorporate the same amount of glass and intro duce some GVD compensation if the shortest pulses are to be measured and delivered to a sample Even before the pulse leaves the laser or the Opal it travels through extra glass For example in a Tsunami laser if we assume the pulse is at its shortest as it passes through the coating of the output coupler it then travels through the output coupler substrate the photodiode beam splitter and the output window For the Tsunami laser the total thickness of these optics is about 1 9 cm Thus a pulse that is 60 fs at the output coupler coating becomes 66 fs by the time it exits the laser Include the glass of an autocor relator and that in any experimental setup and the pulse can be broadened substantially GVD Compensation Since most autocorrelators use beam splitters a lens and often a spinning block as in the Spectra Physics Model 409 08 the pulse is also broad ened i
78. ect the Set actual wavelength field then use the up down push buttons to set it to the actual measured value Caution M DO NOT change the Zeroth Order at value c Run Scan Length from the Setup menu again d Measure the actual wavelength again If the wavelength shown is still off by more than 3 nm align the servo wavelength monitor at this time following the instructions in Appendix C When com plete repeat this entire step then continue 7 Select Adj Temp from the Main menu then select Temp Table Shift and adjust the temperature offset up and down to optimize Signal output power and stability Optimum stability is achieved when Temp Table Offset is 0 5 to 1 096 below maximum power operation This completes the alignment procedure for the 1 3 um configuration Go to Chapter 6 Operation for instructions on day to day operation Installation and Alignment Opal Alignment 1 5 pim Optic Set The 1 5 um optic set is used when the desired Signal wavelength output is between 1 35 and 1 6 um The alignment procedure for the 1 5 um optics set uses a similar procedure to the 1 3 um optic set but it is not necessary to employ prisms Pr and Pr in the cavity This is because the LBO crystal exhibits negative GVD in this wavelength region and additional dispersion compensation is not required to obtain a near transform limited output pulse 810 nm is the optimum Tsunami pump wavelength for the 1 5 um optics set
79. eel 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 sales 9 splasers com www spectra physics com
80. egarding the use of the Manual Control menu 5 22 Installation and Alignment 19 Scan M to obtain a flash a From the Manual Control menu select Motor on the same menu and press the down button to the right of the display to move M toward one end of its range Watch for a flash During translation a flash of green or orange light should appear within the cavity b Ifaflash is observed move M back to the position that produced it and skip to Step 20 c Ifno flash is observed by the time M has reached the end of its travel translate it in the other direction until a flash is observed At that time move M back to the position that produced it and skip to Step 20 d If the Opal fails to flash in either direction re measure the cavity length as outlined under Initial Set up above then repeat the entire alignment Steps 1 through 19 If still no flash is observed refer to the troubleshooting guide in Chapter 8 or call your Spectra Physics service representative 20 Adjust M and M horizontally and vertically to optimize light intensity A well aligned cavity produces a small amount of green light that is most visible at Ms Completing the Cavity Alignment Warning W 1 Close the shutter and replace the high reflector in M with the appropri ate output coupler for the 1 5 um wavelength The 3 point registry in the optics holder ensures good resetability of the optic Screw the optic holder in finger t
81. ent to change the battery every 2 years regardless of use f 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 s Ss um x em cu H ecce bn gt Eja Write Protect Write Protect Write Protect 7 d P 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 D 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 the size and part numbers vary Mitsubishi MF3513 LCDATO1 Silver with blue patch and white edge trim Screw retains battery Battery BR2325 Epson Plain gray card with black edge trim Latch retains battery Battery CR2025 D 1 Opal fs Synchronously Pumped Optical Parametric Oscillator 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 Scr
82. es Follow the principles below whenever you clean any optical surface Clean only one element at a time then realign that element for maxi mum output power Do not remove the optic to clean it unless specifi cally told to do so If optics are removed and replaced as a group some might get swapped At best all reference points will be lost making realignment extremely difficult Work in a clean environment and whenever possible over a soft lint free cloth or pad Wash your hands thoroughly with liquid detergent Body oils and contaminants can render otherwise fastidious cleaning practices useless Always use clean powderless and lint free finger cots or gloves when handling optics and intracavity parts Remember not to touch any contaminating surface while wearing gloves you will transfer oils and acids onto the optics Use filtered dry nitrogen canned air or a rubber squeeze bulb to blow dust or lint from the optic surface before cleaning it with solvent per manent damage can occur if dust scratches the glass or mirror coating Caution n Do not use canned air to clean the crystal A rapid change in tempera ture due to freon sputter can cause permanent damage to the crystal Freon sputter is common if the can is not held vertically Use spectroscopic grade solvents to clean all optics except the crystal Use spectrophotometric grade hydrocarbon solvents to clean the crys tal Since cleaning simply
83. es temperature control of the nonlinear crystal and therefore wave length selection 4 7 Opal fs Synchronously Pumped Optical Parametric Oscillator 4 8 Chapter 5 Opal Installation Note Note E Installation and Alignment This chapter contains installation and alignment procedures for the Opal A Spectra Physics service representative will perform the initial system alignment and cleaning at the time of installation Thereafter there should be little need to do a full alignment The Cavity Alignment section is pro vided in the event either a gross misalignment has occurred or you need to convert from 1 3 to 1 5 um operation or vice versa Allow only qualified personnel to align your system All Opal system controls and connections are defined in Chapter 4 Con trols Indicators and Connections Refer to your Millennia User s Manual and your Tsunami User s Manual for information on setting up and operating those systems The following installation procedures are provided for reference only they are not intended as guides for the initial installation and set up of your system Please call your Spectra Physics service representative to arrange an installation appointment which is part of your purchase agreement Allow only personnel qualified and authorized by Spectra Physics to install and set up your system You will be charged for repair of any damage incurred if you attempt to install the system yourse
84. essary reflections or scattering Figure 2 2 VISIBLE AND OR INVISIBLE VISIBLE AND OR INVISIBLE LASER RADIATION LASER RADIATION AVOID EYE OR SKIN EXPOSURE TO DIRECT OR AVOID EYE OR SKIN EXPOSURE TO SCATTERED RADIATION DIRECT OR SCATTERED RADIATION CLASS 4 LASER PRODUCT POWER WAVELENGTH S AND PULSE WIDTH DEPEND ON PUMP OPTIONS AND LASER CONFIGURATION POWER WAVELENGTH AND PULSE WIDTH DEPEND ON PUMP SEE OPTIONS AND LASER CONFIGURATION MANUAL CLASS IV LASER PRODUCT SEE MANUAL 0451 8080 Figure 2 1 These CE and CDRH standard safety warning labels would be appropriate for use as entry warning signs EN 60825 1 ANSI 4 3 10 1 Figure 2 2 Folded Metal Beam Target Use of controls or adjustments or the performance of procedures other than those specified herein may result in hazardous radiation exposure Follow the instructions contained in this manual the Tsunami User s Man ual and the Millennia pump laser User s Manual for safe operation of the Opal system At all times during operation maintenance or service of your Opal avoid unnecessary exposure to laser or collateral radiation that exceeds the accessible emission limits listed in Performance Standards for Laser Products United States Code of Federal Regulations 21CFR1040 10 d Any electronic product radiation except laser radiation emitted by a laser product as a result of or necessary for the operation of a laser
85. ets from 1 3 um to 1 5 um operation 1 2 Close the Opal shutter Back Pr out of the beam path to allow an unobstructed beam path from Ms to Mg Remove mirrors M through M and place them in their protective stor age containers Do not remove Mgp and M p Install the 1 5 um optics listed in Table 5 3 into Opal However instead of putting the output coupler into M install the high reflector provided in the optics kit This aids in alignment later Table 5 3 Optical List for 1 5 um Operation Optical Position Part Number Output Coupler M G0324 023 High Reflectors M M5 Mg M G0380 002 High Reflectors M3 M G0079 021 High Reflector M with PZT Assy 0449 1850 5 Setthe Tsunami pump laser to 810 nm at 2 W and verify that it is mode locked 6 Open the Opal shutter 7 From the Setup menu verify the Tsunami pump wavelength is set to 810 nm and the optics set is set to 1 3 1 6 uum then run the Scan Length command This will calibrate the wavelength and set the default crystal tempera ture to either the previously stored settings or to the factory pro grammed temperature offset 8 Place the Opal wave plate into the Tsunami pump beam and rotate the wave plate to rotate the pump beam polarization 90 90 rotation is achieved when the reflection of the Tsunami beam from the front surface of the crystal exhibits an intensity minimum 9 Align the Opal cavity according to the procedure outlined in
86. ew retains battery Battery BR2325 Procedure The idea is simple leave the card in the controller and with the controller on to provide power to the memory replace the battery Warning 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 D 1 shows memory cards from Mitsubishi Panasonic and Epson Note the Epson card shown is the most commonly used card and is the first Epson type listed above It has no labeling Caution 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 Warning The battery is not secured by the holder and will fall out of the holder as W 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 1 With the controller power on and the PCMC
87. f each mount It also includes the double pass distance of the fold mirrors Installation and Alignment f Subtract the total measured distance of the Opal cavity length from that of the Tsunami laser i e find the difference between the two g Loosen the two large Allen hex screws that secure the M mount to the base plate of the Opal and slide the mount to the point where the Opal cavity length matches that of the Tsunami If required move the entire M mount to another set of mounting holes in the base plate The holes are 2 54 cm apart Aligning the Pump Beam power to minimum while aligning the pump beam Do not allow the focused beam from P to make contact with the temperature sensor on the side of the crystal or its bonding agent or the heater cooling unit below the crystal Even a low power focused beam may cause damage and or deposit a film onto the crystal face Also the differential temper ature resulting from focusing the beam near the crystal edges can cause the crystal to fracture Crystal damage due to the above is not covered by your warranty Warning Y To prevent damage to the crystal during this procedure reduce Tsunami Use an ir viewer to align the pump beam 1 Set the Tsunami pump power to minimum 2 Open the Opal shutter and verify the Tsunami pump beam is centered on P If the beam is not centered on P refer to Aligning the Opal Head earlier in this chapter for instructions 3 A
88. f the Servo Wavelength Monitor Assembly If necessary reposition the servo housing which is secured to the base plate by two 4 20 button head screws Caution Do not use the Allen hex head adjustment of the beam splitter this will destroy the factory wavelength calibration 5 24 Installation and Alignment Using an ir detector verify the Signal beam reflected from the front surface of the beam splitter is centered on the grating in the servo housing The beam spot should be positioned on the grating as shown in Figure 5 7 In order to see the spot on the grating it may be necessary to man ually rotate the grating using the Manual Control menu refer to Chap ter 4 If the beam spot is not centered as shown a Usethe black adjustment knob on the beam splitter to center it hor izontally b Center the beam vertically by making very small adjustments to Ms M5 and M Do not lose oscillation use the Manual Control menu to adjust the position of M for maximum output power after each incremental adjustment Verify any visible light contained in the output beam is blocked by the filter attached to the Signal output Brewster window Figure 5 8 The filter is shipped in the accessory kit and must be installed before the Opal can be used the first time Remove the two 2 56 x 44 in cap screws securing the Signal Brewster window to the Opal head and install the filter assembly along with the window assembly to the out
89. for power and mode quality 3 Verify the standard optics set 720 850 nm is installed in the Tsu nami laser Refer to your Tsunami User s Manual for instructions on identifying and changing optics 4 Optimize Tsunami output and verify laser output power is 52 W at 810 775 and 750 nm Also verify pulse width and wavelength range are within specifications It has been demonstrated that the most stable performance of the Opal is obtained when it is pumped with over 2 W of 100 fs about 9 nm of bandwidth pulses from the mode locked Tsunami laser In order to do this two modifications to the Tsunami are necessary 5 5 Opal fs Synchronously Pumped Optical Parametric Oscillator a Install the single plate birefringent filter as the tuning element This replaces the slit assembly The filter is included in the Opal accessory kit Refer to the sections on removing the slit assembly and installing the birefringent filter in your Tsunami User s Man ual b Change the output coupler to the one supplied with the Opal acces sory kit refer to Table 8 3 in the Replacement Parts list at the end of Chapter 8 Refer to the Changing Optics procedure in your Tsunami User s Manual for directions on installing M 5 Reduce the Millennia laser output power to minimum Close the pump laser shutter 7 Remove the Opal head cover a Pull outward on the bottom of the four cover latches until they snap b Press downward on the cove
90. from their mounts for cleaning However only mirrors Ms Mg the output coupler OC and the beam splitter must be removed from their holder to clean the second surface 1 Use a squeeze bulb dry nitrogen or canned air to clean away any dust or grit before cleaning the optics with solvent If using canned air avoid tilting the can This prevents freon from being sputtered onto the optic 2 Clean the optic using the drop and drag method Figure 7 1 Ry a m i Figure 7 1 Drop and Drag Method 7 4 Don t Touch Maintenance a Hold the optic horizontal with its coated surface up Place a sheet of lens tissue over it and squeeze a drop or two of acetone or meth anol onto it b Slowly draw the tissue across the surface to remove dissolved con taminants and to dry the surface Pull the tissue slow enough so the solvent evaporation front fol lows the tissue i e the solvent dries only after leaving the optic surface 3 For stubborn contaminants and to access hard to reach or awkward places e g the Brewster windows use a tissue in a hemostat to clean the optic a Fold a piece of tissue in half repeatedly until you have a pad about 1 cm square and clamp it in a plastic hemostat Figure 7 2 While folding do not touch the surface of the tissue that will contact the optic or you will contaminate the solvent Ium pana Figure 7 2 Tissue Folded for Cleaning b If required cut the paper w
91. ge The Opal is entirely solid state and uses no laser dyes or complex cryogen ically cooled crystals It employs a lithium triborate LBO nonlinear opti cal crystal to generate new infrared frequencies and is pumped by the output of the Tsunami mode locked Ti sapphire laser The system comprises the Opal head and the Opal electronics control mod ule The Opal head is the same shape as but a little longer than the Tsu nami laser head and it is designed to be placed near the Tsunami output port The electronics module has the same footprint as the Tsunami Model 3955 electronics module which allows the latter to be placed on top of it to conserve space The Opal control electronics are microprocessor based and system param eters and settings are displayed via a back lit LCD screen on the front panel Selection and control of these operating parameters are easily made via menus displayed on the screen Buttons located below the screen are used to select menus appropriate to the task at hand They are also used to select various fields areas within these menu Once selected the up down push buttons located to the right of the screen are used to increase or decrease the value of the selected field or to change the contents from a pre selected list 1 1 Opal fs Synchronously Pumped Optical Parametric Oscillator Figure 1 1 The Opal shown as part of a complete system Included are a BeamLok 2080 pump laser a Tsunami Lok t
92. gth um Figure 3 7 Wavelengths most affected by vapor absorption 1 600 3 7 Opal fs Synchronously Pumped Optical Parametric Oscillator Opal Specifications Table 3 1 Opal Specifications Output Characteristics Opal Performance Signal Output 1 3 um with 1 5 um with 775 nm pump 810 nm pump Average Power 5150 mW 5150 mW Pulse Width23 130 fs 130 fs Tuning Range 1 10 1 35 um 1 35 1 60 um Repetition Rate Nominal 82 MHz Noise lt 1 Stability lt 5 Spatial Mode TEMoo Beam Diameter at 1 e points 2 0 mm Beam Divergence full angle 1 0 mrad Polarization Horizontal gt 100 1 Specifications subject to change without notice and only apply when pumped at 775 or 810 nm 2 W lt 80 fs by a Spectra Physics Tsunami Millennia system N Specifications apply to operation at wavelength noted with an appropriate pump wave length A seck pulse shape 0 65 deconvolution factor is used to determine the pulse width Idler output wavelengths are also accessible at 1 4 2 25 um and 1 63 2 00 um respectively Power levels are typically 5096 of the signal For operation below 1 18 um 750 nm pump or lower is required Rms measured in a 10 Hz to 1 MHz bandwidth n 7 Percent power drift in any 1 hour period after an 1 hour warm up and less than 3 C temperature change 3 8 Outline Drawings 12 24 gt 31 09 3 60 5 29 934 13 44
93. h M position etc The up down push buttons to the right of the screen allow you to modify the con tents or value of the selected field Changeable fields include e Scan range e Signal and Idler wavelength setting e Absolute temperature setting Temperature offset table shift or single point offset e Motor M position e Loop on off e Stepper count setting e Local remote control selection and associated operating parameters e Optics set selection e Wavelength units um or cm e 7user set and 3 fixed Opal operating configurations Save recall The Menus This section describes the seven menu groups Use the flowchart in Figure 6 2 as a guide The screen menus are placed in functional groups and to assist you the menu descriptions are listed in the order in which they appear on screen within their functional group The screen name is listed first followed by the group name shown in parenthesis The help screens and the system comment screens are not presented as they are self explanatory When a box is displayed around a variable the variable can be changed using the up down arrows To select a different variable use the Next Field key to toggle to the variable you wish to change A small flashing up down arrow displayed in some menu screens indi cates a process is in progress and the system is not stabilized Wait until the flashing arrow disappears before continuing with the setup 6 7 Opal fs
94. h extreme care and attention to detail Clean is a relative description nothing is ever perfectly clean and no cleaning operation can ever completely remove contaminants Cleaning is a process of reducing objectionable materials to acceptable levels 7 1 Opal fs Synchronously Pumped Optical Parametric Oscillator Equipment Required e dry filtered nitrogen or canned air e rubber squeeze bulb e optical grade lens tissue e spectrophotometric grade methanol and or acetone for general optics e spectrophotometric grade HPLC toluene or xylene Aldrich Gold Label for cleaning the crystal hemostats clean lint free finger cots or powderless latex gloves Removing and Cleaning Opal Optics Danger Laser Radiation 7 2 Warning ll The Tsunami laser and its pump laser are Class IV High Power Lasers and with the Opal have output beams that emit high power laser radia tion By passing the safety interlock shutters on these systems you can be exposed to hazardous radiation Always wear proper eye protection and follow the safety precautions in Chapter 2 Laser Safety For safety always close the pump laser shutter when you change optics Remove clean and install mirrors one at a time in sequence to avoid acci dental exchanges and loss of alignment reference After cleaning and replacing each mirror open the pump laser shutter and adjust the mirror vertically and horizontally for maximum output
95. h the purge line to the Opal output bezel by pressing the hose connector onto its mating connector until it snaps in place Cut the PTFE line between the Tsunami laser and the Model 3910 ata convenient location and insert the T connector To attach the tubing to the barbed T connector heat the tubing with a flameless heat source heat gun then quickly slide the tubing onto the barbed fitting while the tubing is still warm Do not move the connec tion until it has cooled Attach the tubing from the Opal to the unused tee fitting Once the lines are installed check for leaks Refer to your Tsunami User s Manual for information on setting the purge for the Model 3910 Installation and Alignment Warning Y Always use dry oil free Electronic Grade 5 or better nitrogen 99 999 pure to prevent contamination of the system Do not purge with nitrogen from a boil off tank or other non approved gas source Do not connect to any source with a pressure greater than 67 kPa 10 psi or damage to the Model 3910 filters will result This completes the installation of the Opal purge line Removing the Opal Purge Line To release the purge line from the Opal press inward on the metal locking flange on the quick disconnect while gently pulling on the hose The quick disconnect automatically shuts off the gas flow when disconnected Opal Alignment 1 3 um Optic Set Warning W Initial Set up The 1 3 um optic set is used w
96. hapter 6 Operation osa ens bake bee dew RR RR RR IT A a aa Ss 6 1 General Operation llsisseleeseeeeeee teeta 6 1 Turning On the System ehh 6 2 Resetting the Wavelength ete 6 4 Turning Off the System cc tte eee 6 4 Puirgingithe Opal SED DUE rium ta eee a ta 6 5 Purge TUMON 12s rese Ex b PX PIA E ad Em PR NANG PE ead xu Rx 6 6 P rge TUOI stet tee RERUM RI Un IR ERE AUF E E CERE 6 6 The Front Panel Menu Control System 0 0000 6 6 Meena Mana ct oo UE est BALA s E ERA HG NG ote ue cL CN 6 7 Main Menu MAIN osei s sninen E ka i RR mI he 6 9 Scan Menu SG AN s nna Aag eR retento aep ees a GN a ir er e a pep hen n edi 6 10 Scan Status Menu SCAN 0 00 reme 6 11 Paused Scan Status Menu SCAN 0000 cette re 6 11 Remote Menu REMOTE 0 000 cece hh 6 12 Adjust Temp Menu ADJUST TEMPERATURE 00 000 eee 6 12 Clear Menu ADJUST TEMPERATURE 0 0000 cece ee 6 14 Setup Menu SETUP 2222 0000 nanana 6 15 Scan Length Menu SETUP sssssssseees mrs 6 16 viii Table of Contents Scanning Coarse Length Menu SETUP sssssessesee ae 6 16 Configure Menu CONFIGURE 22222 sh 6 17 Save Recall Menu CONFIGURATION ssssssssss eee eet eee 6 17 Miscellaneous CONFIGURATION 222 ehh 6 18 Diagnostics Menu DIAGNOSTICS sssseslell lr 6 19 Manual Control Menu DIAGNOSTICS sssss
97. hen the desired Signal output wavelength is between 1 1 and 1 35 um The alignment procedure is similar to that for the 1 5 um set except that after performing what is essentially a 1 5 um align ment procedure with 1 3 um optics installed the cavity is realigned with prisms Pr and Pr installed and with M and M as the operating cavity mirrors Prisms Pr and Pr are required since in the 1 1 to 1 35 um wave length region it is necessary to introduce some negative group velocity dis persion into the cavity to obtain near transform limited output pulses 775 nm is the optimum Tsunami pump wavelength for operation from 1 18 to 1 35 um 750 nm is the optimum pump wavelength for 1 10 to 1 18 um Unless expressly stated otherwise perform the following procedures with Tsunami output power set to minimum Close the Opal shutter 2 Calculate the physical cavity length of the Tsunami laser a b Set the Tsunami wavelength to 775 nm Optimize the Tsunami output beam quality with 2 W of output power Ensure the laser is mode locked with a stable pulse train refer to Tsunami manual Adjust the pulse width to about 100 fs i e such that the output pulse width has about 9 nm of bandwidth Use a frequency counter to obtain the Tsunami repetition rate This can be done conveniently by connecting the MONITOR output of the Model 3955 to a frequency counter The effective cavity length is calculated using the following equation
98. ial Uses Tel 41 22 919 0211 Fax 41 22 919 0300 Internet custserv lec ch 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 2 10 Laser Safety Equipment and Training Laser Safety Guide Laser Institute of America 12424 Research Parkway Suite 125 Orlando FL 32826 Tel 407 380 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 Opal fs Synchronously Pumped Optical Parametric Oscillator 2 12 Chapter 3 OPOs Opal Description Since the early 1990s the mode locked Ti sapphire laser has become the system of choice for ultrafast laser applications The Spectra Physics Tsu nami mode locked Ti sapphire oscillator provides the most flexible com mercial system with 1 wavelength coverage from 690 to 1080 nm ii a pulse width range from 50 fs to gt 80 ps iii average power up to 2 W iv outstanding long term stability and v activ
99. ichtbare sch dliche grosa electromagn tica onzichtbare gevaarlijke Housing gereux en cas d ouverture elektromagnetische Strahl visible e invisible con el electromagnetische stral Label et lorsque la s curit est ung wenn Abdeckung dispositivo de seguridad ing indien geopend en 4 neutralis e ge ffnet und Sicherheits abierto o con su indi interlock overbrugd verriegelung berbr ckt caci n alterada Bedienungsanleitung beachten CDRH Ouverture Laser Exposi Austritt von sichtbarer und Por esta abertura se emite Vanuit dit apertuur wordt Aperture tion Dangereuse Un Ray unsictbarer Laserstrahl radiacion laser visible e zichtbare en niet zichtbare Label onnement laser visible et ung nicht dem Strahl aus invisible evite la exposi laser straling geemiteerd 6 invisible est emis par cette setzen cion vermijd blootstellilng ouverture CE Rayonnement Laser Visi Gefahr Sichtbare und AI abrir y retirar el disposi Gevaar Zichtbare en Warning ble et Invisible en Cas unsichtbare Laserstrah tivo de seguridad exist onzichtbare laserstraling Label D Ouverture et lorsque la lung Bestrahlung von radiaci n laser visible e Vermijd blootstelling van 9 securite est neutralisee Auge oder Haut durch invisible evite que los ojos oog of huid aan directe exposition dangereuse de direkte oder Streustrahlung ola piel queden expuestos straling of terugkaatsingen l oeil ou de la peau au ray vermeiden Laserklasse IV tanto a la radi
100. idle even when the system is not used This will keep the crystal at an elevated temperature and will prevent recrystalli zation which damages the crystal If you must turn off the electronics you must first remove the crystal from the unit and store it in the dry environment of a desiccated chamber Crystal damage due to improper handling is not covered by your warranty A service engineer from Spectra Physics will install the crystal assembly into your system the first time and he will adjust its position for optimal output Thereafter you will need to note its position in the beam by making a small pencil mark on the cooling tower and dovetail slide so that once removed it can be reinstalled to this same position This ensures that your system will meet specification time and time again without having to do a total realignment each time The following sub sections explain how to remove the crystal and reinstall it and how to optimize its position in the beam in the event the original location marker is erased Before Removing the Crystal 1 Remove the beam shield from behind the crystal then mark the loca tion of the reflected pump beam from the crystal surface 2 Verify the crystal is centered in the pump beam a Slide the waveplate into the Tsunami beam then rotate it until you see the position of the Tsunami beam on the input and output face of the crystal b Readjust the crystal position so that the crystal is centered
101. iec saiat eee ru 2 7 CE Declaration of Conformity Emissions 0 000 0c cette 2 8 CE Declaration of Conformity Low Voltage cece 2 9 Sources for Additional Information 0 0 00 cee eee 2 10 Laser Safety Standards suana cece eee 2 10 Equipment and Training 0 0 een teeta 2 11 Chapter 3 Opal Description 0 cece eee eee eee eee eee 3 1 OPOS ER 3 1 The Opal apan Pen LG kgs beketuriw 4 deu keen R Leives tpULSead dy eux e 3 3 Wavelength Tuning Characteristics snusa aaua es 3 4 Configuration oda sy TM a De EE DR TRUE ux RN ER MEN utet a 3 5 The Opal Electronics Module 0 000 cece hr 3 6 Purging the Cavity reisse deme eie NE aa pis ges on baa eet an Poll te sah eee fan 3 6 Opal Specifications zitat iaa e eme PAGAN NB DONNA ERU Seda a hae EVE SA We 3 8 Outline Drawings um ico DUI e deu vex an EI UP ERR 2 on PUERUM eR Net E 3 9 References aside iD eR dans uie Xu dame wid 2 ERE e E EP 3 9 vii Opal fs Synchronously Pumped Optical Parametric Oscillator Chapter 4 Controls Indicators and Connections L ss 4 1 Opal Head RN RC cC 4 1 Input Bezel Connections 000 hh rs 4 2 Opto Mechanical Controls 000 cee ehh hr 4 2 Opal Electronics Module 2 2 ehh 4 5 Front Panel user PNPA NEA gp eere t AS tah Gg e Ged en CEPR 4 5 Bear Panel cac org bad ht e ees en dod Ed ap UR e ke es Ghee ed aba e E aed 4 6 Chapter 5 Installat
102. ight but do not over tighten Open the shutter and readjust M vertically and horizontally slightly to re establish lasing Do not screw the optics holder too tight Over tightening will at mini mum distort the optic and at worst chip it and possibly render it use less Tighten only until slight resistance is felt If the Opal oscillates again skip to Step 7 If it fails to oscillate 2 Translate M back and forth slightly using the Manual Control menu as you did before and look for a flash on an ir detector card placed out side the Signal window Total translation should be no more than 1 mm If the Opal begins oscillating skip to Step 7 If it fails to oscillate 3 Place the ir detector card midway between M and M so it detects a small amount of the pump beam reflected from M and so the small hole in it allows part of it to pass through Adjust M horizontally and vertically to reflect this pump beam back through the hole in the card Remove the card and scan M as you did before and look for a flash 5 23 Opal fs Synchronously Pumped Optical Parametric Oscillator a If you do not observe a flash replace the output coupler with the high reflector then reoptimize the cavity for maximum intracavity visible light generation To do this adjust M and M and make small translational adjustments of M with the motor control b When intracavity visible light is maximized repeat Steps 1 through 5 If
103. in the pump beam 3 Close the Opal shutter Measure the distance from the front edge of the M mirror to the near edge of the crystal and write it down for use later when reinstalling the crystal 5 Square the long edge of the business card along the front face of the M mount and mark the location of the near edge Brewster corner of the LBO crystal 6 Measure the distance between M to M and M to P and write it down 5 3 Opal fs Synchronously Pumped Optical Parametric Oscillator Warning W 7 Note the location of the crystal tower with regard to the dovetail base Removing the Crystal Assembly l pho uar O Adjust the Tsunami for about 200 mW of output power Reduce iris to a minimum Verify the Opal shutter is closed Loosen the locking setscrew with a 64 Allen driver Back the crystal assembly away from the dovetail base until it comes free Rotate the adjustment screw counterclockwise with a 3 32 Allen driver Turn off the Opal electronics and disconnect the crystal cable Place the crystal in a desiccated chamber such as the one in which it was shipped Reinstalling the Crystal Assembly l Install the new crystal assembly by pulling the assembly onto the dovetail base until it is at the same location as that noted in Step 7 of Before Removing the Crystal above In the following steps exercise extreme caution when translating the crystal with the Tsunami beam present Avoid c
104. ince the exact temperature for optimum performance is also dependent upon several other factors such as input angle of the pump wavelength cavity alignment etc the temperature adjust option is provided It is possible to either shift the entire temperature table or offset a single point in the table Temp Table Shift allows the operator to shift the entire table of stored temperatures This adjustment produces the same temperature offset at every wavelength and can be applied to the original stored phase matching Operation temperatures or to a set of temperatures which have been optimized under the single point offset procedure see below Also once a single point off set procedure has been implemented the temperature table shift option is useful to fine tune the system for optimum performance on a day to day basis Single Point Offset allows the operator to optimize Opal performance at a particular wavelength or at several wavelengths The change in temperature is displayed as an offset from the stored temperature and is applied only at the displayed wavelength With any two offsets defined in this manner the system automatically interpolates the points in between This allows facile acquisition of a table containing optimized single points Note that the entered optimized points are denoted by an asterisk that follows the off set percent while non asterisk points are interpolated End points for all wavelengths are considered
105. incorporated into that product Laser Safety Safety Devices Shutter Interlock Danger Laser Radiation Because the energy to drive the process in Opal comes from another laser and not from an internal source such as electrical discharge the interlock differs slightly from that of solid state or ion lasers The Opal has a single shutter interlock that blocks the pump beam at the entrance to the housing to prevent lasing When installed the cover holds the shutter interlock open for normal operation When the cover is removed the shutter closes automatically Figure 2 3 shows the Opal shutter interlock Input Shutter in Defeated Open Position Input Bezel Figure 2 3 Laser Head Shutter Interlock Operating Opal or the Tsunami laser with the cover removed may expose people to high voltages and high levels of ir radiation It also increases the rate of optical surface contamination and defeats the pur pose of the purgeable sealed cavity For both these reasons operating the system with these covers removed is not recommended The alignment procedures in this manual require internal adjustments while the laser beam is present The interlock can be defeated to allow this When the cover is removed and access to the beam is required raise the red shutter lever to defeat the interlock and hold the shutter open In this posi tion the red lever clearly shows the defeat status and prevents cover instal lation until the
106. intensity candela cd temperature celcius C pressure pascal Pa capacitance farad F angle radian rad Prefixes tera 10 T deci 10 d nano 10 n giga 10 G centi 107 c pico 107 p mega 10 M mill 10 m femto 105 f kilo 10 k micro 109 U atto 1013 a XV Unpacking and Inspection Unpacking Your Laser Your Opal laser accessory was packed with great care and all containers were inspected prior to shipment the Opal left Spectra Physics in good condition Upon receipt of your system immediately inspect the out side of the shipping containers If there is any major damage such as holes in a box or cracked wooden frame members insist that a representative of the carrier be present when you unpack the contents Carefully inspect your system as you unpack it If you notice any damage such as dents scratches or broken knobs immediately notify the carrier and your Spectra Physics sales representative Keep the shipping containers If you need to return the system for upgrade or service the specially designed shipping containers assure adequate pro tection of your equipment Spectra Physics will only ship Spectra Physics equipment in original containers you will be charged for replacement con tainers You will find the following items packed in an accessory kit included with the Opal head e an Allen hex wrench tool kit three foot clamps for mounting the Opal head and this manual e optics cleaning materi
107. ion and Alignment 5 1 Opal Installation s eot ta Sb ctr Me eth Oe aree er pcd E ete Sae ud 5 1 Setting Up the System a xxt RR D En ia Ert e E ERRARE 5 2 Removing Installing the LBO Crystal nh 5 3 Aligning the Opal Head hh 5 5 Attaching the Opal Purge Line tenes 5 7 Removing the Opal Purge Line 2 hrs 5 9 Opal Alignment 1 3 um Optic Set ees 5 9 Initial SET UP 424 ser ext ELDER Web ANN HAAN a GG EE d ud de dde as 5 9 Aligning the Pump Beam 2 socie e e E ER Wek eda eee ARX ERE E 5 11 Aligning the Opal Cavity i id ares ee tae den cep BG e ke NG gen bales 5 12 Alignment of Pr and Pro Prism Sequence ssssseesese ne 5 14 Completing the Cavity Alignment Rn 5 15 Aligning the Beam to the Servo Wavelength Monitor Assembly a 5 16 Completing the Alignment saaan aaea 5 17 Opal Alignment 1 5 um Optic Set eee tenes 5 19 Initial Set Up 2a eret d ur ener edet ire ud ote cand Pee ee does 5 19 Aligning the Pump Beant die yu o bI RESCUE RE Seance ETE E E 5 20 Aligning the Opal Cavity de dnte ttr IER en C Lo Pc Sae ra geh DA RA i 5 21 Completing the Cavity Alignment eR Rm rn 5 23 Aligning the Beam to the Servo Wavelength Monitor liliis 5 24 Completing the Alignment RR mr 5 25 Converting from 1 3to0 1 5 UM aeta tenets 5 27 Converting from 1 5 to 1 3 Hm acs oue sess Peed eb ede weet ETRE LS E RV GERE 5 28 C
108. ited 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 the terms and condi tions of the sales order shall prevail The Opal is protected by a 12 month warranty All mechanical and optical parts and assemblies are unconditionally warranted to be free of defects in workmanship and material for one 1 year following delivery of the equip ment 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 Warranty repairs or replacement equipment is warranted only for the remaining unexpired portion of the original warranty period applicable to the repaired or replaced equipment 9 1 Opal fs Synchronously Pumped Optical Parametric Oscillator 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 Spectra Phy
109. ith a solvent cleaned tool to allow access to the optic c Saturate the tissue with acetone or methanol shake off the excess resaturate and shake again Do not allow excess solvent to flow onto unwanted areas such as optic adhesives and mounts d Wipe the surface in a single motion Make sure that the hemostat does not touch the optic surface or the coating may be scratched 4 After placing the optic you just cleaned into the beam inspect it using an ir viewer to verify the optic actually got cleaner i e you did not replace one contaminant with another This completes the general procedure for cleaning optics except for the crystal 7 5 Opal fs Synchronously Pumped Optical Parametric Oscillator General Procedure for Cleaning the Crystal Clean the crystal only when you cannot obtain specified power a after cleaning all the other optics b after performing the standard alignment procedure outlined in Chapter 6 Operation Turning On the System and c after translating the crystal so that the beam passes through a cleaner or undamaged area ture due to freon sputter can cause permanent damage to the crystal Caution Do not use canned air to clean the crystal A rapid change in tempera Freon sputter is common if the can is not held vertically can be destroyed if excess pressure is used Also DO NOT USE ACE TONE OR METHANOL ON THE CRYSTAL Use a spectrophotometric grade hydrocarbon solven
110. ity greater than 1000 nm In an OPO wavelength conversion is achieved through parametric down conversion in a nonlinear optical crystal Figure 3 2 An input pump pho ton a3 is split into lower energy signal and idler q photons such that energy is conserved i e Oh E Q7 1 or in terms of wavelength Ld 1 2 p 3 1 Opal fs Synchronously Pumped Optical Parametric Oscillator Output Coupler Signal Output ag H Pump Input Non Linear Crystal L High Reflector Idler Output Figure 3 1 A Typical Optical Parametric Oscillator Configuration Widler SoS S 20 pump signal Second Harmonic Generation Parametric Down Conversion Figure 3 2 Optical frequency three wave conversion process Momentum conservation k kk 3 is achieved by using a birefringent nonlinear crystal and by satisfying the phase matching conditions Ba NOT NG 4 where 7 is the refractive index The process requires crystals with a high second order nonlinear suscepti bility and can be viewed as the inverse of second harmonic generation or sum frequency mixing Parametric down conversion has much lower effi ciency however since both signal and idler waves as opposed to only the 2 wave in second harmonic generation must build up from quantum noise Therefore high conversion efficiencies in OPOs are generally attained by resonating the signal wave Since gain is only availa
111. l become difficult b Adjust the translation screw to move the crystal to a new position Take small steps and be extremely careful when translating the crystal so that the focused beam does not fall on the crystal temper ature sensor the heater cooler or their bonding agents c Tighten the setscrew 8 Tune the Tsunami laser to 830 nm increase its output power to 2 W and verify it is mode locked 9 Open iris all the way 10 Slide the wave plate into the pump beam 11 Rotate the wave plate until the reflected beam from the front surface of the crystal has minimum intensity This corresponds to a p polarization state of the Tsunami pump beam i e the polarization of the Tsunami output has been rotated 90 Aligning the Opal Cavity 1 Place a white card midway between M and Mp You will see a reflected low intensity pump beam with some fre quency doubled blue light on the card 2 Using the birefringent filter in the Tsunami adjust the output wave length of the Tsunami laser slightly to maximize the amount of fre quency doubled light observed on the card The frequency doubled blue light is collinear with the Opal intracavity beam and can be used to align the Opal cavity The beam appears as a figure 8 as shown in Figure 5 6 a Figure 8 The waist defines the center of the beam Figure 5 6 Figure 8 frequency doubled blue beam 3 Remove the card then adjust M vertically and horiz
112. lf and such action may void your warranty The general alignment instructions below do not contain procedures for aligning the servo wavelength monitor system This system is self aligned when you initiate a scan from the Setup menu If calibration of this system is required refer to Appendix C Servo Wavelength Cali bration Procedure We strongly recommend you do not alter the factory preset settings Doing so might require a service call and such a call is not covered under your warranty Opal fs Synchronously Pumped Optical Parametric Oscillator Setting up the System Most of the tools signal cables and equipment you need to set up the Opal are in your accessory kit 1 Place the Opal head 12 cm in front of the Tsunami laser head as shown in Figure 5 1 such that the input port is directly in line with the Tsu nami output port 2 Place the Opal electronics module in a convenient location If it makes sense to stack the electronics modules place the Model 3955 on top of the Opal electronics module and on top of the Model 3930 if using a Lok to Clock Tsunami The Opal electronics module should be within 2 m of the Opal head 3 Connect the heater cable 5 pin connectors between the heater con troller connector on the Opal output bezel to the HEATER connector on the rear panel of the electronics module 4 Connect the signal ribbon cable between the 25 pin D sub connector on the Opal output bezel and the TO O
113. more than 3 nm perform the following Otherwise skip to Step 7 For reference Table 5 2 shows relative values for various sys tem components for an Opal output of 1 500 um Table 5 2 Typical Settings for Opal Output at 1 500 um Opal Pump Nom Grating Nom Crystal Wavelength um Wavelength nm Setting steps Temperature 1 500 810 1596 64 a From the Diagnostic menu press Cal Wavelen to get to the Wave length Calibration sub menu b Select the Set actual wavelength field then use the up down push buttons to set it to the actual measured value Caution n DO NOT change the Zeroth Order at value c Run Scan Length from the Setup menu again d Measure the actual wavelength again If the wavelength shown is still off by more than 3 nm align the servo wavelength monitor at this time following the instructions in Appendix C When com plete repeat this entire step then continue 7 Select Adj Temp from the Main menu then select Temp Table Shift and adjust the temperature offset up and down to optimize Signal output power and stability Optimum stability is achieved when Temp Table Offset is 0 5 to 1 096 below maximum power operation This completes the alignment procedure for the 1 5 um configuration Go to Chapter 6 Operation for instructions on day to day operation 5 26 Installation and Alignment Converting from 1 3 to 1 5 uim The following procedure allows you to change optics s
114. mp laser or the SPPO itself The servo system monitors the spectrum of the signal output pulse using a grating and a bi cell photodetector The difference between the input signals of the left and right halves of the bi cell detector is the error signal used by the servo system to control the position of the fine cavity length control mirror The mirror is correctly positioned when this difference is driven to zero The output wavelength as reported by the Opal electronics is determined by the angle of the grating which is mounted on a stepper motor and controlled through the micropro cessor 3 5 Opal fs Synchronously Pumped Optical Parametric Oscillator The Opal Electronics Module The Opal electronics module is designed for easy operation The tempera ture of the LBO crystal and the entire servo system including the cavity length adjustments are microprocessor controlled This allows for auto mated wavelength tuning and automated setup via a simple menu driven program In addition to the logic control functions the module contains the crystal heater driver and sensing circuit as well as drivers for the M PZT driven mirror and the motor controlled output coupler M4 System parameters and settings are displayed via a back lit LCD screen on the front panel Selection and control of these operating parameters are made via a layered menu system Soft push buttons located below the screen provide the user an interface through
115. mped Optical Parametric Oscillator Soft Keys Save stores one set of scan parameters with optimized temperature off sets for later use The information is stored in the memory location desig nated by the number shown in the menu The memory location is changed using the up down push buttons Memory locations 0 through 6 are pro vided for use by the user Recall retrieves one set of scan parameters with optimized temperature offsets for later use The information is retrieved from the memory location designated by the number in the box in the menu The memory location is changed using the up down push buttons Numbers 0 through 6 are for use by the user Numbers 7 through 9 contain parameters stored at the factory Main Menu returns to the Main menu Miscellaneous CONFIGURATION Wavelength Units um 23 EEE 488 BAUD 9600 Address 15 Bits 8 Parity None Stop Bits 1 The Miscellaneous menu reports to the Configure menu From here the wavelength display units um or cm can be selected as can the parame ters for the optional RS 232 and IEEE 488 interfaces sented that reminds you to save your current configuration which also saves your offset information If you fail to do this before switching from one wavelength unit to the other any configuration changes made since the last save including offsets will be lost see Save Recall menu Caution W When selecting to change between um and cm se
116. n t Touch Eyewear Required t Uu by W 8 A 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 Laser radiation is present Condition or action may present a hazard to personal safety Condition or action may present an electrical hazard to personal safety Condition or action may cause damage to equipment Action may cause electrostatic discharge and cause damage to equip ment Condition or action may cause poor performance or error Text describes exceptional circumstances or makes a special refer ence Do not touch Appropriate laser safety eyewear should be worn during this opera tion Refer to the 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 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
117. n the autocorrelator before it is measured This means the pulse out of the Tsunami or Opal may be actually shorter than that indicated by direct measurement Consequently GVD must also be compensated for when using an autocorrelator Since the sign of GVD in material is generally positive for the wavelengths produced by the Tsunami laser and the Opal introducing negative GVD into the beam path compensates for the broadening effect of the material Negative GVD can be introduced into a system with prism pairs grating pairs or a Gires Tournois Interferometer GTI The prism pair provides the easiest lowest loss means for compensating for the positive GVD of mate rials A prism pair is used for this reason in the Opal 1 3 um configuration For the 1 5 um configuration it is not necessary to use the prism pair because the LBO nonlinear crystal actually has negative GVD in this wave length range To compensate for pulse broadening from materials a simple setup using two high index SF 10 prisms is all that is necessary Figure B 4 shows the layout top and side views for an easily built pre compensation unit Prism 1 Input Beam Prism 2 Pick off Mirror To Autocorrelator High Experiment Reflector Side View Beam path shown for a particular frequency component of the pusle Prism 2 Higher Frequency Blue Lower Frequency Prism 1 Red Direction in which to translate Prism 1 to add more p
118. nlet connector allows clean dry nitrogen gas to be input into the Opal from the Model 3910 which is provided with the Tsunami laser Heater controller connector attaches to the HEATER connector on the Opal electronics rear panel This circuit provides power and temperature sensing for the crystal heater Servo connector 25 pin D sub attaches to the TO OPAL HEAD connec tor on the Opal electronics rear panel via a ribbon cable It provides signals and feedback for the PZT Mg mirror the motor driven M output coupler and the wavelength servo system Opto Mechanical Controls Most of the mirror controls have vertical and horizontal adjustments They are color coded for identification green for horizontal blue for vertical Pump beam waveplate rotates the polarization state of the Ti sapphire laser light and assists in the initial alignment of the Opal The waveplate is rotated by turning its edge It is manually slid in and out of the input pump beam using the small vertical lever Pump beam mirror P directs the input pump beam onto the center of pump beam mirror P Its vertical and horizontal adjustments are accessible from outside the Opal Pump beam mirror P directs the pump beam through iris and onto the center of pump beam mirror P It has vertical and horizontal adjust ments idler Output Servo Wavelength Monitor Assy m Signal Output
119. nm align the servo wavelength monitor at this time following the instructions in Appendix C When com plete repeat this step then continue Opal fs Synchronously Pumped Optical Parametric Oscillator 9 To optimize the pulse width of the signal use the Adjust Temp menu and make small temperature adjustments while monitoring the pulse width with an autocorrelator If the 1 3 um optic set is installed use the micrometer adjust on prism Pr to vary the amount of prism glass in the intracavity beam This adjusts the group velocity dispersion GVD of the Opal cavity Use an autocorrelator to measure the pulse width For information on GVD and how to compensate for it refer to Appendix B Resetting the Wavelength If the system has not been used for a long time or if alternate wavelength ranges are desired it might be necessary to do one or more of the follow ing 1 Find the Tsunami Opal cavity match point using the Scan Length func tion on the Setup menu Change the Tsunami pump wavelength 3 Change the temperature of the crystal to optimize the performance at a given wavelength using the Adjust Temp menu 4 Change optics sets to accommodate the desired Signal and Idler wave length ranges For this Pr and Pr might need to be moved in or out of the beam and the output coupler M might have to be adjusted to opti mize cavity length The latter is moved using the Manual Control menu If you are changing optic sets refer to
120. ns This may be different than the value returned by the source wlen query when the wavelength is not stable READ WNUM cR Read Wave Number Reads the operating wavelength in wave numbers This may be different than the value returned by the source wnum query when the wavelength is not stable E 3 Opal fs Synchronously Pumped Optical Parametric Oscillator SCANLENGTH cR Run Scan Length Same as pushing Scan Length button from the Laser Setup menu A suc cessful scan results in the LOOPON and WLSET bits being set in the status byte Note During the checking the calibration phase of the scan length opera tion the Opal system will not respond to commands queries RECALL x cR Recall Operating Configuration Used to recall operating configurations just like the Recall Configurations menu SAVE x cR Save Operating Configuration Used to save operating configurations just like the Save Configurations menu Additional Commands Required by the IEEE 488 2 Standard CLS cR Clear Status Command Clears the Event Status Register ESR ESE xxx cnR Standard Event Status Enable Command Sets the Event Status Enable ESE register This is a mask on the bits in the event status register ESR The logical AND of the ESE and ESR registers is reported in bit 5 of the Status Byte see STB This register is initial ized to zero ESE cR Standard Event Status Ena
121. ns can be performed in either increasing or decreasing wavelength increments However because decreasing the Signal wavelength corre sponds to increasing the temperature of the LBO crystal this scan direction is recommended As the system is scanning a symbol flashes until it reaches the next sta bilized wavelength Once stabilized the symbol disappears and the WAVE LENGTH STABILIZED signal on the electronics rear panel goes high to allow unattended data acquisition The selectable field variables are the from and to Signal wavelengths the corresponding Idler wavelengths are calculated from the Signal wavelengths the step size in um or cm the dwell time and the number of times the scan is to be performed times Step size reso lution is 1 nm minimum dwell time increments are 0 1 s with a maximum of 99 9 s and the maximum number of scans is 99 When scanning in wave numbers cm the smallest increment for the 1 5 um optics set is 4 cm for the 1 3 um optics set it is 5 cm Soft Keys Next Field moves the highlight box surrounding the Signal from field to one of the other five fields so that the variable can be changed using the up down push buttons Start Scan starts the scan process based on the parameters selected using Next Field When the scan starts the Scan Status menu is displayed to show the status of the scan Main Menu returns to the Main menu Operation Scan Status Menu SCAN
122. nstalling this line Set up a wavelength detection device a monochromator and tune the Tsu nami laser for the correct wavelength Refer to Table 6 1 to verify the Tsu nami pump wavelength is appropriate for your desired Opal wavelength Initiate a Scan Length from the Setup menu to allow the system to self cali brate at the selected wavelength Symptom Problems with pulse width Possible Causes Corrective Action Temp offsets are set incor rectly Opal is not properly purged Incorrect dispersion 1 3 um optics only Adjust the temperature offset from the Adjust Temp menu for optimum power pulse width pulse stability and or pulse shape Refer to Chapter 6 Operation Purging the Opal and for information on which wavelengths are greatly affected by oxygen and water vapor and on how to set the purge rate If your system is not set up for purging refer to Chapter 5 Installation and Alignment Attaching the Opal Purge Line for information on installing this line Adjust Pr for optimum pulse width 8 3 Opal fs Synchronously Pumped Optical Parametric Oscillator Symptom Opal Flashes but will not lock when Scan Length is initiated Possible Causes Corrective Action Misaligned servo grating wave Refer to Appendix C for information on calibrating the servo grating wave length assembly length assembly System has old software Check your software rev number in the Diagnostics About O
123. nters 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 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 Cygnes Building 2 19 Uchihirano Cho Chuo ku Osaka Telephone 81 6 6941 7331 Fax 81 6 6941 2700 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 splasers com sales 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 Opal fs Synchronously Pumped Optical Parametric Oscillator 9 4 Appendix A Setting the Line Voltage Switch The line voltage switch part of the power connector on the Opal electron ics module must match your local line voltage The Opal electronics mod ule is shipped from the factory with the line voltage selected for the location
124. o Clock pump laser the Opal and the Opal Doubler Also shown in the upper right corner is the Model 409 08 autocorrelator The Opal accessories kit includes a single plate birefringent filter and a special high transmission output coupler that are to be used in the Tsunami pump laser when it is used to pump the Opal Together they provide the necessary output power and pulse width to pump the Opal optimally Patents The Opal contains technology that is unique among synchronously pumped optical parametric oscillators This technology is covered by the following United States patents 5 017 806 5 365 366 5 377 043 5 847 861 1 2 Configurations Introduction The Opal is available in two configurations e Opal 1 3 um which provides a signal wavelength from 1 1 to 1 35 um e Opal 1 5 um which provides a signal wavelength from 1 35 to 1 60 um If you purchased any of the above configurations and require operation in another wavelength range the following wavelength conversion sets are available e Opal 1 3 to 1 5 which includes all the necessary optics to convert an Opal 1 3 to an Opal 1 5 e Opal 1 5 to 1 3 which includes all the necessary optics mounts prism assemblies etc to convert an Opal 1 5 to an Opal 1 3 In addition your Opal can be purchased with the Opal PPO an option that includes optics mounts and a Brewster window to allow access to the Tsu nami beam which is reflected off the Opal LBO nonlinear c
125. of equal intensity and an adjustable optical delay is imparted to one The two beams are then recom bined within a nonlinear crystal for second harmonic generation The effi ciency of the second harmonic generation resulting from the interaction of the two beams is proportional to the degree of pulse overlap within the crystal Monitoring the intensity of uv generation as a function of delay between the two pulses produces the autocorrelation function directly related to pulse width Two types of autocorrelation configurations are possible The first type known as interferometric and shown in Figure B 1 recombines the two beams in a collinear fashion This configuration results in an autocorrela tion signal on top of a constant dc background since the second harmonic generated by each beam independently is added to the autocorrelation sig nal Alternatively if the two beams are displaced from a common optical axis and then recombined in a noncollinear fashion Figure B 2 the back ground is eliminated because the uv from the individual beams is separated spatially from the autocorrelator signal This configuration is called back ground free autocorrelation B 1 Opal fs Synchronously Pumped Optical Parametric Oscillator Beam Splitter Photomultiplier Tube A uv Filter EI Non linear Crystal A lt lt Lens TEE ag llllll 4 Incoming Beam Adjustable Mirror i Delay A Y Mirror Figure B 1 In
126. of intended use If it is incorrect you must change it prior to applying power to the system The following directions are provided so you can make the change yourself 1 Remove the cover plate fuse block assembly to expose the voltage selector card Refer to Figure A 1 Use a small screwdriver to gently pry off the cover plate A slot is pro vided for screwdriver access Power Switch Power Cord Connector yn Voltage Selector oy PS Card iz NG N N Occ Holder Bracket Orc The four orientations of the voltage selector card Figure A 1 Power Switch Line Cord and Voltage Selector Module 2 Remove the voltage selector card The voltage selector card comprises a white plastic indicator pin and a small pc board about 2 cm 0 8 in square Refer to Figure A 1 Using needle nose pliers gently grasp the pc board and remove it from the module A side to side motion will assist in its removal A 1 Opal fs Synchronously Pumped Optical Parametric Oscillator 3 Select the voltage There are four voltage selections one written on each edge of the pc board with a small arrow pointing to it a Measure your facility outlet voltage then rotate the pc board until the edge with the measured voltage printed on it faces the inside of the module arrow points into the module b Move the white indicator pin in the pc board slot so
127. ons of adjusting P and P and repositioning the pump beam to accomplish this Observe the beam entering the crystal If you observe a bright spot on the surface of the crystal a high scattering site due to a surface flaw or burn translate the crystal slightly to an area that produces the least amount of reflectance Do not move the beam near the edge of the crystal a Loosen the setscrew that locks the translation stage in place just enough so that the stage can be translated If loosened too much the stage becomes loose on the dove tail and alignment will become difficult b Adjust the translation screw to move the crystal to a new position Take small steps and be extremely careful when translating the crystal so that the focused beam does not fall on the crystal temper ature sensor the heater cooler or their bonding agents c Tighten the setscrew Open iris all the way Slide the wave plate into the pump beam Rotate the wave plate until the reflected beam from the front surface of the crystal has minimum intensity This corresponds to a p polarization state of the Tsunami pump beam i e the polarization of the Tsunami output has been rotated 90 Place a white card midway between M and Mp You will see a reflected low intensity pump beam with some fre quency doubled blue light on the card Using the birefringent filter in the Tsunami adjust the output wave length of the Tsunami laser slightly to maximize the
128. ontacting the focused beam with the thermoepoxy on the bottom of the crystal as well as with the temperature sensor on the side of the crystal Contact with either of these will ablate material onto the crystal and will damage it Such dam age is not covered by your warranty Connect the crystal cable and turn on the Opal electronics Open the Opal shutter and use an ir viewer to verify the Tsunami beam is fully contained in the crystal Still using the ir viewer rotate the crystal until the reflected beam is at the same marked location noted in Step 1 of Before Removing the Crystal Adjust M until the distance from near edge of the crystal to M is the same as that measured in Step 4 of Before Removing the Crystal Readjust the spacing for M to M3 and M to P to match that measured in Step 6 of Before Removing the Crystal Slide the waveplate into the beam and rotate it until you see the Tsu nami beam on the input and output face of the crystal If necessary adjust the crystal position so that the crystal is centered in the beam Install the beam shield behind the crystal Installation and Alignment Adjusting the Crystal Temperature and Offset This process sets the crystal temperature to the factory setting By first adjusting the table offset to obtain the correct temperature at the tested wavelength a minimum amount of point offset can be retained 1 Verify the current wavelength is the same as the test
129. ontally to direct the blue beam to the center of the front face of M 4 To increase the intensity of the second harmonic beam remove the output coupler at M and replace it with the additional high reflector provided in your optics kit Less loss will aid in the initial alignment Remember to close the shutter while changing optics 5 Adjust M to center the blue beam through iris and onto the center of the front face of M 5 12 Installation and Alignment Close a little to verify the beam is centered Iterate between adjust ments of M and M to center the beam through I and onto M4 6 Adjust M vertically and horizontally to reflect the blue beam back through the center of iris lp then fully open Ip 7 Adjust M to direct the blue beam through iris and onto the center of Ms Close l a little to verify the beam is centered Once centered open it fully 8 Verify the blue beam path is clear of prism Pr If it is not use the micrometer to adjust prism Pr until it is out of the blue beam path 9 Adjust M to center the blue beam onto the center of Mg 10 Adjust Mg to center the blue beam onto the center of high reflector M 11 Adjust M to send the reflected beam back through the center of iris ls a Place a white card with a small hole about 2 mm in it midway between Mg and M and position it so that the blue light from Mg passes through the hole Holding the card in place adjust M so that the reflec
130. ositive GVD Top View Dispersion shown Figure B 4 Using two prisms to compensate for positive GVD B 5 Opal fs Synchronously Pumped Optical Parametric Oscillator The laser pulse travels through the first prism where different frequency components are spread in space Then the broadened pulse travels through the second prism strikes a high reflector and reflects back along its origi nal path with one exception The high reflector is slightly tilted in the plane perpendicular to the spectral spreading and causes the pulse to travel back through the prisms at a slightly different vertical height so that it can be picked off After the beam returns through the first prism it is reflected by another mirror to the autocorrelator and or the experiment This setup allows the higher frequencies blue to catch up with the lower frequencies red This is not intuitively obvious since it appears that the higher frequencies actually travel a longer path length than the lower fre quencies However it is the second derivative of the path with respect to wavelength d P d that determines the sign of the GVD Table B 2 and Table B 3 provide dispersion values at 800 nm for materials and grating prism pairs Dispersion D is expressed in units fs cm of path length Table B 2 Positive Dispersion Values 800 nm Material D fs cm Fused Silica 300 BK 7 450 Ti sapphire 580 SF 10 1590 Table B 3 Negative Dispersion Values
131. pal menu It should be rev 2 21 or newer If not call your Spectra Physics representative Incorrect software parameters Verify the proper parameters have been selected in the Setup menu for the have been selected optics set used Wrong optics set is installed for Verify the correct optics set is installed by checking the numbers against the wavelength you selected those found in the Replacement Parts list found at the end of this chapter Refer to Chapter 7 Maintenance Removing and Cleaning Opal Optics for directions on changing and identifying optics Noisy pump laser Adjust the Tsunami laser for optimum performance Working in a region of low gain Adjust the Opal wavelength a little closer to the degeneracy point see Figure 3 4 then use the Setup menu to perform a Scan Length Optimize output by adjusting M and M or M p then tune for the desired wavelength Opal not properly purged Refer to Chapter 6 Operation Purging the Opal and Table 6 1 for informa tion on which wavelengths are greatly affected by oxygen and water vapor and on how to set the purge rate If your system is not set up for purging refer to Chapter 5 Installation and Alignment Attaching the Opal Purge Line for information on installing this line Symptom Long term stability problems Possible Causes Corrective Action Feet are not secure on Opal Verify both the Opal and Tsunami are clamped securely to the table and that and or Ts
132. ptronics and Photonics Spectra buyer s guides Consult the ANSI and ACGIH standards listed at the end of this section for guidance Maintain a high ambient light level in the laser operation area This keeps the eye s pupil constricted thus reducing the possibility of eye damage Keep the protective cover on Opal and the lasers at all times Avoid looking at the output beam even diffuse reflections are hazard ous Avoid wearing jewelry or other objects that may reflect or scatter the beam while using Opal or the lasers Use an infrared detector or energy detector to verify the laser beam is off before working in front of the Opal or the pump lasers Operate the lasers at the lowest beam intensity possible given the requirements of the application Expand the beam whenever possible to reduce beam power density Avoid blocking the output beam or its reflection with any part of your body 2 1 Opal fs Synchronously Pumped Optical Parametric Oscillator Caution n e Establish a controlled access area for laser operation Limit access to those trained in the principles of laser safety e Post prominent warning signs near the laser operation area Figure 2 1 e Set up experiments so the laser beam is either above or below eye level e Provide enclosures for beam paths whenever possible e Set up shields to prevent specular reflections e Setup an energy absorbing target to capture the laser beam preventing unnec
133. r diagnostic purposes and for use during initial system alignment when access to the coarse motor control is required in order to move M The parameters displayed in this menu can be changed independently they are no longer linked together under soft ware control Therefore once changed the system may not operate cor rectly when you return to normal operation The Manual Control menu reports to the Diagnostics menu From here many system parameters can be modified to optimize the system and be monitored to determine the cause of any problems Bar graphs display out put power the relative position of the PZT and the servo error signal Err Output power level is also displayed numerically next to the Power bar 6 19 Opal fs Synchronously Pumped Optical Parametric Oscillator graph Parameter fields that can be changed using the Next Field soft key are e crystal temperature in percent of total range e wavelength or step count grating angle toggle e M position and e servo loop status on or off Temperature is expressed here as a percentage of total range 0 100 and not as an offset as it is in the Adjust Temp menu This way small changes in temperature can be made in order to fine tune wavelength and power output The steps um soft key toggles between displaying grating wavelength or stepper motor step count Setting the stepper motor to a certain step count sets the grating at an angle corresponding to a partic
134. r to release the pressure on the latches then pull the top portion of the latch from the notch in the cover c Using the slotted finger grips at each end of the cover remove the cover and set it aside 8 Adjust the Opal head height a Loosen the locking nuts on the feet They are tightened against the bottom of the base plate b Use a 32 Allen hex wrench to adjust the feet from the inside of the head Adjust the feet so the baseplate is parallel to the table top and the center of the Signal and Idler output windows are about 14 5 cm above the table 9 Open the pump laser shutter and increase its pump power so that the Tsunami output is just above threshold minimum Tsunami power 10 Align the Opal head to the Tsunami input pump beam a Close iris l4 b Raise the Opal interlock shutter lever to the override position Pull the red capped lever to the vertical position Danger Overriding the safety interlock shutter may expose the user to hazardous A X Laser Radiation laser radiation Be aware that invisible radiation is emitted from the out put of the Tsunami laser as well as from various optical components in the Opal when the Opal cover is removed and its shutter is open Always wear proper eye protection and follow the safety precautions in Chapter 2 Laser Safety c Position the Opal head so the pump beam passes unobstructed through the input window and strikes the center of pump mirror P refer to Figu
135. re 5 2 d If readjustment of the Opal feet are required do it now Verify the base plate is parallel to the table then tighten the locking nut on each foot 5 6 Installation and Alignment Input i pe E Residual Servo uy on idler Fi Pump Port Wavelength 4 Aperture Ss E Output Monitor Assy M Output Coupler Ms RPM Signal TOP Output __ Beam Splitter Motor controlled Mirror Crystal Assembly Figure 5 2 Opal Cavity Layout e Keep P centered on the beam and move the Opal output end hori zontally so that the head is roughly parallel to the beam Close the pump laser shutter g Secure the Opal head to the table with the three foot clamps pro vided The clamps slide over the lower portion of each foot This completes the installation of the Opal head Attaching the Opal Purge Line If you are going to operate the Opal in a region where there is significant absorption due to water vapor refer to Figure 5 3 you will need to purge the Opal The Tsunami laser comes with a Model 3910 for this purpose Refer to your Tsunami User s Manual for installation instructions Because the wavelength regions that are affected by water vapor or oxy gen absorption are different for the Tsunami and Opal only one system requires purging at a time For example when operating the Tsunami in a region
136. ribed in Chapter 5 Installation and Alignment Refer to the Tsunami User s Manual for information regarding the Ti sapphire wavelength regions affected by oxy gen and water vapor Due to the strength of the absorption lines shown in Figure 6 1 the mois ture level within the cavity must be below 1000 ppm to allow problem free output For these wavelengths we recommend using 99 999 pure dry oil free Electronic Grade 5 nitrogen Transmittance 1 100 1 200 1 300 1 400 1 500 1 600 Wavelength um Figure 6 1 Wavelengths most affected by vapor absorption 6 5 Opal fs Synchronously Pumped Optical Parametric Oscillator Purge Turn on 1 Verify the Opal cover is in place and clamped down sealing the cavity 2 Verify the nitrogen tank output regulator is set to minimum then turn on the nitrogen supply 3 Setthe bottle output regulator to limit pressure to less than 67 kPa 10 psi 4 Open the Opal purge bleed valve Figure 4 1 and leave it open for the first 2 hours of operation then close it 5 Usethe Model 3910 flow control to set the nitrogen flow rate For all wavelengths set the starting purge rate to 0 3 m hr 10 SCFH for at least 2 hours Then for operation below 1 18 um or operation between 1 33 and 1 48 um reduce the purge rate to 0 17 m hr 6 SCFH for the duration of the experiment for all other wavelengths set the purge to 0 014 m hr 0 5 SCFH This completes
137. rmance 1 3 um optics set only Signal or idler is too close to If operating the Opal at wavelengths other than those suggested you might degeneracy point need to change the pump wavelength in order to move the Signal or Idler wavelength further away from the degeneracy point Refer to Table 6 1 Symptom Wavelength not calibrated Possible Causes Corrective Action Servo grating wavelength Refer to Appendix C for information on calibrating the servo grating wave assembly is misaligned length assembly Beam is not centered on the Verify the Signal beam is centered on the output coupler and horizontally aperture to the servo wave centered on the aperture of the servo grating wavelength assembly If it is length grating assembly not use M and M to make the correction Ensure the beam is centered on the bi cell adjust the horizontal control of the beam splitter if necessary refer to Aligning the Beam to the Servo Wavelength Monitor in the 1 3 or 1 5 um alignment sections in Chapter 5 Once the beam is centered initiate a Scan Length from the Setup menu to allow the system to self calibrate 8 2 Service and Repair Symptom Low Power Possible Causes Corrective Action Tsunami pulse is too narrow Low pump power Temp offsets set incorrectly Wave plate is in the beam An iris is closed or there is an obstruction in the beam path externally or internally Optics prisms are dirty cw break
138. rmation on why and how to set the crystal offset temperature Noisy Tsunami laser Optimize the performance of the Tsunami laser Refer to its user s manual Noisy pump laser purge rate is If you are purging the pump laser with nitrogen or an external purge pump too high you might need to reduce the flow rate Refer to your pump laser user s man ual for information on proper flow rates Opal cavity is misaligned Optimize Opal output by adjusting M and M and if you have to check the cavity alignment Refer to Chapter 5 Installation and Alignment The Opal or Tsunami Brewster Inspect the Brewster windows on the Opal and clean them if necessary windows are dirty Refer to the Maintenance chapter in the appropriate manual for cleaning information Uncontrolled lab environment Check and correct for any conditions that might cause vibrations or perturba causes external vibrations per tions of the optical table e g air conditioning fans or noisy water lines Ver turbations ify there is little change in room temperature and or the pump laser cooling water 4 0 C and humidity 595 Also ensure there is not a direct flow of air from a register or air vent onto the table Dirty optics Clean the optics Refer to Chapter 7 Maintenance for information on how and when to clean Opal optics Refer to your Tsunami user s manual for information on how to clean its optics cw breakthrough Tsunami Use the prism dispersion
139. ropriate temperature for the crystal based on the known Tsunami pump wavelength and the Opal cavity length is automatically adjusted through the grating bi cell servo system The servo system provides a measurement of the signal wavelength and is calibrated automatically by the Opal electronics module each time Scan Length is performed from the Setup menu during start up The Opal oscillator is designed for easy operation from the Opal electron ics module Day to day operation requires the Opal electronics module to be left on continuously and when the system is not being used placed in the idle mode to minimize drift and warm up time and more importantly to keep the hygroscopic crystal hot and dry refer to warning below Due to the hygroscopic nature of the LBO crystal you must keep the crystal contained in a dry environment at all times and minimize the exposure time to the environment even during installation Install the crystal and turn on the Opal electronics immediately to bring the crystal temperature above ambient then leave the electronics on with the crys tal temperature set at idle even when the system is not used This will keep the crystal at an elevated temperature and will prevent recrystalli zation When the electronics must be turned off you must remove the crystal from the unit and store it in the dry environment of a desiccated chamber Crystal damage due to improper handling is not covered by your warranty
140. rs maintenance and service Included is a replacement parts list and a short troubleshooting guide Customer Service contains a general warranty statement and explains how to request service should you ever need it It includes a list of world wide Spectra Physics service centers you can call if you need help The Maintenance section contains information you need to keep your Opal clean and operational on a day to day basis whereas 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 This product has been tested and found to conform to Directive 89 336 EEC for Electromagnetic Compatibility Class A compliance was demon strated for EN 50081 2 1993 Emissions and EN 50082 1 1992 Immunity 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 compliance 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 EC Declaration of Conformity in Chapter 2 Laser Safety Opal fs Synchronously Pumped Optical Parametric Oscillator This equipment has been designed and teste
141. rystal The Opal PPO provides over 250 mW of Tsunami output that can be extremely useful for diagnostics purposes or for use in pump probe experiments The Opal is supported with a full range of accessories that includes the Opal Doubler for operation from 560 to 660 nm and from 690 to 790 nm and the Model 409 08 autocorrelator Please contact your local Spectra Physics sales representative for more details 1 3 Opal fs Synchronously Pumped Optical Parametric Oscillator 1 4 Chapter 2 Laser Safety Danger ur The Opal Tsunami and the Millennia pump laser are Class IV High Power Lasers that have output beams that are by definition safety and fire hazards Take precautions to prevent exposure to direct and reflected beams Even diffuse or specular reflections can cause severe skin or eye damage Danger Laser Radiation Because the Opal and the Tsunami laser emit cw and short pulsed invis ible infrared radiation they are extremely dangerous to the eye Infrared radiation passes easily through the cornea which focuses it on the ret ina where it can cause instantaneous permanent damage Precautions for the Safe Operation of Class IV High Power Lasers and Accessories 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 vendors are listed in the Laser Focus World Lasers and O
142. s ignored if the Opal is in wavenumber mode SOURCE WLEN lt cr gt Read Wavelength Reads the desired signal wavelength in microns also see read wlen SOURCE WNUM xxxx lt cR gt Set Wave Number Sets the desired signal wavelength in wave numbers cm and immedi ately moves the Opal toward the specified wavelength Progress can be monitored with the read wlen and STB commands This command is ignored if the Opal is in microns mode SOURCE WNUM cR Read Wave Number Reads the desired signal wavelength in wave numbers also see ead wnum SOURCE TOFF xx x cR Set Temperature Offset Sets the percentage temperature offset for the current operating point This is a single point offset The table shift cannot be changed via computer This command should only be given if the wavelength is stable see the WLSET bit in the status byte SOURCE TOFF cn Read Temperature Offset Reads the percentage temperature offset for the current operating point This is a single point offset The table shift cannot be queried via com puter READ POWER cn Read Output Power Reads the current output power 0 to 100 percent READ PZT cR Read PZT Position Reads the current PZT position 0 to 100 percent READ TEMP lt cr gt Read Crystal Temperature Reads the current crystal temperature 0 to 100 percent READ WLEN cR Read Wavelength Reads the operating wavelength in micro
143. sessess n 6 19 Scanning Coarse Length Menu DIAGNOSTICS 000 0 cece ae 6 21 Wavelength Calibration DIAGNOSTICS 00 0000 eee 6 21 Chapter 7 Maintenance wii cece ee eee eae NEE ANAN eee ee eee weeks 7 1 Notes on the Cleaning of Laser Optics 20 0000 cece 7 1 Equipment Required ra ae A E tee ees 7 2 Removing and Cleaning Opal Optics 0 00 0c cette 7 2 Standard Cleaning Procedures re 7 3 General Procedure for Cleaning all Optics Except the Crystal 00 aaa 7 4 General Procedure for Cleaning the Crystal 0 000 c eee tees 7 6 Chapter 8 Service and Repair 000 e cece eee eee eee eee 8 1 Troubleshooting Guide rhum Phe ee oderam me he AG Par ee neds ie p ce es 8 1 Replacement Pangi na a bn bees See i eee eee Guede ALIGN dele gle wed NG NARING ie 8 6 Chapter 9 Customer Service 9 1 Warrant a eth e at athe MG cA A AN hla eee hi Pa GT Eh kag At Oh at hein Ge AAD AE a 9 1 Return of the Instrument for Repair eh 9 2 SONICS Centers ios esr Siue Nep re qeu wel Ru RE eai P LES 9 3 Appendix A Setting the Line Voltage Switch 2 222 A 1 Appendix B GVD Compensation 2222 2 ees B 1 INIKOQUGTION M CCP pm B 1 The Autocorrelation Technique ccc e m n B 1 Measurement of Ultrashort Pulses 00 ce rn B 1 Signal Interpretation 000 ccc teas B 4 GVD Compensation in Measurement of Ul
144. sics will provide at its expense all parts and labor and one way return shipping of the defective part or instrument if required This warranty 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 Spectra Physics control 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 you order new ones Spectra Physics will only return instruments in Spectra Physics containers Warning Always drain the cooling water from the head before shipping Water Uu expands as it freezes and will damage the unit Even during warm spells or summer months freezing may occur at high altitudes or in the cargo hold of aircraft Such damage is excluded from your warranty coverage 9 2 Service Ce
145. t 1 3 1 6 810 nm pump assumed Check that Tsunami is at 810 nm Next Full Scan Field Align Length The Setup menu reports to the Main menu Through it the optics set is specified and the pump wavelength is selected 1 5 um 1 3 1 6 um optic set If this assumption is incorrect set this Caution n The system assumes 810 nm is selected for the pump wavelength for the field to the correct wavelength or Opal will not operate as expected The Optics set wavelength field is in um even if the general wavelength units are set to cm via the Miscellaneous menu The pump wavelength field is in nm and can be set in increments of 1 nm System comments are displayed below these fields Changeable variables are selected using the Next Field soft button then changed by pressing the up down push buttons The two choices are 1 3 1 6 when the 1 5 um optics set is used and 1 1 1 4 when the 1 3 um optics set is used The Full Align soft button brings up a series of help menus that step through a Tsunami and Opal mechanical alignment A complete alignment proce dure can be found in Chapter 5 Installation and Alignment Soft key push button either bring up the previous help screen the next screen or return control to the Setup menu The Scan Length soft button starts a scan and brings up the Scan Length menu where the scan search for the Tsunami Opal cavity match point can be monitored see the Scanning Coarse Length menu belo
146. t such as toluene or xylene to clean the crystal Do not allow the solvent to touch the mounting plate or it will destroy the glue holding the crystal to the mount Such damage is not covered under your warranty Warning u DO NOT CLEAN THE CRYSTAL UNLESS ABSOLUTELY NECESSARY It Do not remove the crystal for cleaning Clean it in place 1 Turn off power to the electronics module and wait about 5 minutes for the crystal to cool down 2 Use a squeeze bulb or dry nitrogen to clean away any dust or grit Pro ceed with cleaning the crystal with a spectrophotometric grade solvent only if cleaning with air was not effective or if the Opal output was not improved by translating the crystal to a new location 3 Usea tissue in a hemostat to clean the crystal a Fold a piece of tissue in half repeatedly until you have a pad about 1 cm square and clamp it in a plastic hemostat Figure 7 2 Don t While folding do not touch the surface of the tissue that will contact the Touch optic or you will contaminate the solvent b Saturate the tissue with toluene or xylene shake off the excess resaturate and shake again and dissolve the glue bonding the crystal to the mount The glue can Caution W Do not use excess solvent The excess might penetrate below the crystal then migrate to the crystal surface and permanently damage it c Wipe the surface in a single motion and wait for the solvent to evaporate Be sure tha
147. t the hemostat does not scratch the crystal surface This completes the general procedure for cleaning the crystal Chapter 8 Danger Laser Radiation Service and Repair This chapter contains a general troubleshooting guide 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 manual For information concerning repair by Spectra Physics see Chapter 9 Customer Service At the end of this chapter in Table 8 1 is a replacements parts list of all the components that can be replaced by you in the field It includes a complete list of optics that are available for the Opal Use this guide if Opal performance drops unexpectedly If you try the fol lowing suggestions and are unable to bring your Opal performance up to specification call your Spectra Physics service representative for help These procedures may require you to adjust or replace optics while using the laser system at high power For safety close the Millennia pump laser shutter every time you change an optic or interfere with the cavity in any way and only open it during alignment Protect yourself with appropriate eyewear at all times Troubleshooting Guide Symptom No flash when Scan Length is initiated Possible Causes Corrective Action Tsunami is not mode locked Verify Tsunami is mode locked Refer to the section
148. ted light from M passes back through the hole in the card b Remove the card Slightly close iris and observe the rear side of l4 Using small increments adjust M to center the reflected blue beam on the rear side of the iris Open the iris fully when completed 12 Place the white card in front of M so that the initial blue beam from M passes through the small hole Then adjust M to overlap the reflected blue beam from M on the hole in the card 13 Remove the white card 14 Slide the wave plate out of the pump beam 15 Set the Tsunami laser to 775 nm with 2 W of average power and ver ify it is still mode locked 16 From the Setup menu if 1 1 1 4 is not displayed for the 1 3 uum optics set select the optics set field then use the up down buttons to select 11 14 17 From the Setup menu if the pump input shown is not 775 select the pump beam field then use the up down buttons to select 775 18 From the Manual Control menu select the Temp field and set the crys tal temperature to 55 Please heed the caution warning in the Man ual Control Menu description Chapter 4 when using this menu 19 Scan M to obtain a flash a From the Manual Control menu select Motor on the same menu and press the down button to the right of the display to move M toward one end of its range Watch for a flash During translation a flash of visible red or orange light should appear within the cavity 5 13 Opal fs Syn
149. ter vapor in the Opal Signal wavelength range 5 8 Figure 5 4 M3 and My Spacing 0 0 tte eee ee 5 10 Figure 5 5 P4 and M4 Spacing 00 ccc hh rs 5 10 Figure 5 6 Figure 8 frequency doubled blue beam 0 00 ee eee 5 12 Figure 5 7 Positioning the Signal beam horizontally on the grating cee eee 5 17 Figure 5 8 Visible Light Filter Side View Attaches to Signal Window lusus 5 17 Figure 6 1 Wavelengths most affected by vapor absorption 0 0 0 eee eee eee 6 5 Figure 6 2 Flowchart of the Opal electronics module menu system 0c eee 6 8 Figure 7 1 Drop and Drag Method 0 0 0 cece eens 7 4 Figure 7 2 Tissue Folded for Cleaning 0 0 c eee eens 7 5 Figure A 1 Power Switch Line Cord and Voltage Selector Module 000 eee eee A 1 Figure B 1 Interferometric Collinear Autocorrelation liliis B 2 Figure B 2 Background free Non collinear Autocorrelation llle B 2 Figure B 3 The Model 409 08 Autocorrelator Optical Path The beam paths are displaced by HRR and HRRz in and out of the plane of the paper so the configuration corresponds to the background free method shown in Figure B 2 aa B 3 Figure B 4 Using two prisms to compensate for positive GVD esses eee B 5 Figure B 5 Broadening Curve sssssessseeeeseee ehh B 8 Figure D 1 Three examples of PCMCIA
150. terferometric Collinear Autocorrelation Photomultiplier Tube pana uv Filter Frequency doubled CE E Autocorrelation Non linear i Signal nan Crystal Retro Prism i i Beam Splitter a EBE SEA AE ASS Incoming Beam Adjustable 8 Delay Retro Prism Figure B 2 Background free Non collinear Autocorrelation B 2 GVD Compensation The Spectra Physics Model 409 08 scanning autocorrelator operates in a background free configuration according to the principles of noncollinear autocorrelation It allows the autocorrelator signal to be conveniently dis played on a high impedance oscilloscope which provides the user with instantaneous feedback of laser performance The optical path of the Model 409 08 is shown in Figure B 3 The Model 409 08 uses a rotating block of fused silica for varying the relative path lengths of both beam paths and the scanning time base is calibrated by moving a calibration etalon of known thickness in and out of one of the beam paths The Model 409 08 can be used over the wavelength range from 650 to 1600 nm and by changing the rotating blocks can be used to measure pulse widths from 25 ps to 80 fs c HRR Calibration z Etalon dove I Mo HRR2 Rotating zi Block Thin Block Shown i i Y Alignment 1 Beam Splitter A cDNA kate fo input M i Main Alignment Beam Iris 1 Splitter 1 cs Lens MT Fiter Xtal O H Cr M3 Alignment Target M Mirror H
151. the grating of the Servo Wavelength Monitor also affects wavelength cali bration In order to perform this calibration the Opal must be lasing but not locked i e the loop must be off This procedure can be performed with either the 1 3 or 1 5 um optic set installed as long as the system is set for the peak wavelength for that set i e 1 3 or 1 5 um respectively Refer to Table C 1 at the end of this chapter for nominal operating parameters This procedure requires adjustment or replacement of optics while using the laser system at high power For safety close the Millennia pump laser shutter every time you change an optic or interfere with the cavity in any way and only open it when you are aligning an optic Protect your self with appropriate eyewear at all times Stepper Calibration Procedure To implement the following procedure the Opal must be operational with output at 1 3 or 1 5 um depending on the optics set installed Verify the settings on the Setup menu in Chapter 6 are appropriate Refer to Table C 1 at the end of this chapter for nominal operating parameters for pump wavelength and optic set range a Go to the Setup menu and select 1 1 1 4 if the 1 3 um optics set is installed or 1 3 1 6 if the 1 5 um set is installed b From this same menu set the assumed pump wavelength to 775 for the 1 3 um optics set or 810 nm for the 1 5 um optics set 2 Verify the Tsunami is optimized with 2 0 W of
152. the RS 232 or IEEE 488 interface The parallel interface is much faster than the serial interface but at the con trol speeds required by the Opal system either is acceptable Note not all systems have these optional interfaces 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 on the rear panel of the Opal controller This appendix describes how to install set up and use these interfaces Chapter 6 The Menus Remote Menu contains information on how to select one of these interfaces for remote control and provides you a means to return control to the controller front panel The Configure Menu Misc allows you to set the address for the IEEE 488 interface and the baud rate for the RS 232 serial interface Two modes of control are available local or remote In local mode the dis play and keys on the Opal controller front panel are used to read and enter parameters initiate operations and monitor system status In remote mode a terminal or computer can be used to perform the same operations In addition to the terminal or computer an interface cable is required to con nect the command source to the Opal controller see Table E 1 and Table E 2 at the end of this chapter Command messages are strings of ASCII characters the computer or termi nal can send to the Opal controller where they are interpreted and imple
153. the command string For example a typical transmission might look like ead wlen r Ps sent to the Opal 1 500 lt LF gt returned by the Opal The following list of remote commands and queries provide full control of the Opal system through either the RS 232 serial or IEEE 488 parallel inter face The Reference List is followed by complete definitions Reference List source wlen x xxx Sets desired signal wavelength in microns source wlen Reads desired signal wavelength in microns source wnum xxxx Reads desired signal wavelength in wave numbers source wnum Reads desired signal wavelength in wave numbers source toff xx x Sets the temp offset for the current operating point source toff Reads 96 temp offset for current operating point read power Reads current output power 0 to 100 read pzt Reads current PZT position 0 to 100 percent read temp Reads current crystal temperature 0 to 100 percent read wlen Reads operating wavelength in microns read wnum Reads operating wavelength in wave numbers scanlength Same as pushing Scan Length button recall x Recalls operating configurations save x Saves operating configurations Using the Optional RS 232 IEEE 488 Interface SOURCE WLEN x xxx cR Set Wavelength Sets the desired signal wavelength in microns The Opal will immediately begin moving toward the specified wavelength Progress can be monitored with the read wlen and STB commands This command i
154. through is coming from the Tsunami laser Poor Tsunami pump mode Opal is not properly purged Pump wavelength is different than that stated in the Setup menu Calibration was run at a differ ent wavelength Broaden the Tsunami pulse to 100 fs about 9 10 nm FWHM of band width Allow the Millennia and Tsunami lasers to warm up about 10 15 min then adjust both lasers for a 2 W output from the Tsunami Adjust the temperature offset for higher power through the Adjust Temp menu Slide the wave plate out of the beam path Verify all three irises are open then verify there is nothing in the beam path such as an alignment card that all shutters are open and that nothing is blocking the pump beam For the 1 5 um optics or for the first half of the 1 3 um alignment ensure Pr is completely backed out of the intracavity beam path Refer to Chapter 7 Maintenance for information on cleaning optics Optimize the Tsunami laser Refer to its user s manual regarding cw break through Optimize the Tsunami laser for pump mode TEMy Small adjustments to the Tsunami M micrometer might be required Refer to Chapter 6 Operation Purging the Opal and for information on which wavelengths are greatly affected by oxygen and water vapor and on how to set the purge rate If your system is not set up for purging refer to Chapter 5 Installation and Alignment Attaching the Opal Purge Line for information on i
155. tics set used Wave plate is in the beam Slide the wave plate out of the beam path An iris is closed or there is an Verify all three irises are open then verify there is nothing in the beam path obstruction in the beam path such as an alignment card that all shutters are open and that nothing is externally or internally blocking the pump beam For the 1 5 um optics or for the first half of the 1 3 um alignment ensure Pr is completely backed out of the intracavity beam path Incorrect optics are installed Verify the correct optics set is installed for the wavelength you intend to use Refer to the Replacement Parts list table at the end of this chapter for a list ing of optics and part numbers Optics prisms are dirty Refer to Chapter 7 Maintenance for information on cleaning optics Symptom Poor performance at a specific wavelength Possible Causes Corrective Action Temperature offsets are incor Adjust the temperature offset from the Adjust Temp menu for optimum Opal rect performance Opal is not properly purged Refer to Chapter 6 Operation Purging the Opal for information on which wavelengths are greatly affected by oxygen and water vapor and on how to set the purge rate If your system is not set up for purging refer to Chapter 5 Installation and Alignment Attaching the Opal Purge Line for information on installing this line Prism Pr is not optimized Adjust Pr for optimum Opal perfo
156. tomer Service At Spectra Physics we take pride in the durability of our products We place considerable emphasis on controlled manufacturing methods and quality control throughout the manufacturing process nevertheless even the finest precision instruments will need occasional service We feel our instruments have excellent service records compared to competitive prod ucts and we hope to demonstrate in the long run that we provide above average service to our customers not only in providing the best equip ment for the money but in addition service facilities that get your instru ment 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 Un
157. transform limited 800 nm pulse going through 2 16 cm of fused silica and 0 25 cm of BK 7 Also assume the use of an SF 10 prism pair pre compensator where the beam passes through a total of 2 mm of prism tip per pass or 8 mm total The GVD for all parts of the sys tem and the length for everything but the prism spacing are known The length can be calculated by setting total GVD 0 GVD Compensation DationLator Paila Pala Paala DaajLaa 0 300 2 16 450 0 25 0 8 1590 L 80 2 20 Therefore L 25 3 cm Note the spacing L is the distance between the two tips of a prism in a dou ble pass configuration or the distance between the two tips in one leg of a four prism sequence The calculated L is shorter than recommended above but since the material dispersion value of SF 10 prisms is so high sliding just a bit more glass in will add a large amount of positive GVD thereby balancing out the prism spacing B 9 Opal fs Synchronously Pumped Optical Parametric Oscillator B 10 Appendix C Caution W Danger Laser Radiation Servo Wavelength Monitor Calibration Complete this calibration only when the actual wavelength differs from the displayed wavelength by more than 3 0 nm after running Scan Length from the Setup menu The latter is a day to day self calibration routine and we recommend you perform this routine each time you start up the Opal system Note the propagation of the output beam to
158. trashort Pulses 0 a B 4 Calculating Pulse Broadening 2 0 00 ccc e B 7 Appendix C Servo Wavelength Calibration Procedure C 1 Stepper Calibration Procedure 00 c ect rre C 1 Appendix D Replacing the PCMCIA Card Battery ll D 1 Card Description Replacement Battery List 0000 res D 1 Procedure 4 Sg seagate eene vised und ic edet eer putem PAANAN BUS EN e IR QR te Enos GNG D 2 Appendix E Using the Optional RS 232 IEEE 488 Interface E 1 SCODE uou Bawa aloe sete eee d Sousa dose dale nity NN aed oad Lia aeu a iura do ef eat uas E 1 OVGrVIOW ue nox ma ch etsi MEE RE na DEC RR Mare ANA SG RT MS DR sae tab LA veda E 1 Format and Syntax Rules 2 2 2 0 eene na eaa ehh E 2 Gomrtiands uictus rat nG ara hada Ap bh FA Maala maan Heb cele ania sas ER Rex E 2 Additional Commands Required by the IEEE 488 2 Standard lilii eiiis E 4 CONNECHONS 2 code icr hue Dewbercbg VEINS WM EN xat a uterus E 6 Opal fs Synchronously Pumped Optical Parametric Oscillator List of Figures Figure 1 1 The Opal shown as part of a complete system Included are a BeamLok 2080 pump laser a Tsunami Lok to Clock pump laser the Opal and the Opal Doubler Also shown is the Model 409 08 autocorrelator 00 0 cet 1 2 Figure 2 1 These CE and CDRH standard safety warning labels would be appropriate for use as entry warning signs EN 60825 1 ANSI
159. ts of two focusing mirrors M and M and a series of flat mirrors M M5 M and Mg plus M or Mgp and M p to extend the cavity to a length of about 1 87 m for a 80 MHz repetition rate The mirrors are highly reflective for the signal wavelengths and highly transmissive for both the pump and idler wavelengths The output coupler M is mounted on a motorized micrometer stage to allow adjustment of the coarse cavity length One intracavity mirror Mj is mounted on a piezo electric trans ducer PZT for fine cavity length control Both mirror positions are con trolled by a microprocessor in the Opal electronics module The idler and the residual pump light that passes through M is collimated by mirror Idler and directed through the idler output port via ldler Pump light that is reflected off the Brewster surface of the LBO crystal is directed through an optional residual pump output port by a flat high reflec tor and collimating lens This option may not be available on your Opal contact your Spectra Physics sales representative if you require this option GVD compensation is accomplished using two Brewster prisms Pr and Pr When Pr is inserted into the intracavity beam path the beam is steered to Mee and Pr and finally M p A servo system actively stabilizes the cavity length of the Opal and thus keeps the output wavelength fixed The output wavelength of an SPPO can drift as a result of cavity length changes in either the pu
160. ttings a notice is pre Soft Keys Next Field moves the highlight box between the various fields so the field variable can be changed using the up down push buttons Main Menu returns to the Main menu Operation Diagnostics Menu DIAGNOSTICS DIAGNOSTICS Temperature 57 5 Servo Setpoint 1 500 8 2168cts Motor Position 50 296 Loop is ON Manual Cal About Ctrl Wavelen Opal The Diagnostics menu reports to the Configure menu It displays critical operating parameters and the system status Through the Manual Control menu the operator can set the temperature of the crystal set the wave length grating angle or step setting set the M position and turn the servo loop on and off The About Opal sub menu provides some system parame ters and shows the system program revision level Soft Keys Manual Ctrl brings up the Manual Control menu Cal Wavelen brings up the Wavelength Calibration menu About Opal brings up a screen that shows the system program revision level that can be used for system tracking and troubleshooting purposes Other system parameters are displayed as well Main Menu returns to the Main menu Manual Control Menu DIAGNOSTICS Caution W Temp 57 5 gtng 1 500um 88 2 Motor 50 296 Power PZT Err Loop is ON Next steps Loop Scan Back Field um On Off Length The Manual Control menu is not intended for use in day to day opera tion It is only intended fo
161. ttle that must be done day to day to maintain the system To create a dust free environment allow purging and eliminate time consuming maintenance the Opal head is sealed All controls required for day to day operation are accessible from the outside The Model 3910 purge regulator filter is provided as part of the Tsunami system to facilitate cavity purging clean dry nitrogen gas keeps dust and moisture out of the Opal head Therefore the head cover should only be removed when absolutely necessary e g when changing optic sets It will be necessary to change the filters in the Model 3910 purge unit from time to time Refer to your Tsunami User s Manual When you finally do need to clean the optics follow the procedures below Notes on the Cleaning of Laser Optics Laser optics are made by vacuum depositing microthin layers of materials of varying indices of refraction onto glass or quartz substrates If the sur face is scratched to a depth as shallow as 0 01 mm 0 0004 in the operat ing efficiency of the optical coating can be reduced significantly and the coating can degrade OPOs are oscillators that operate with gain margins of a few percent Losses due to unclean optics which might be negligible in ordinary optical systems can disable the system Dust on optical surfaces can cause loss of output power damage to the optics or total failure Cleanliness is essential and you must apply laser optics maintenance techniques wit
162. ular wavelength Set ting the wavelength results in a system calculated grating angle When combined with the servo loop on off control off the position of M can be modified to investigate the movement of the PZT or changes in the servo error signal As from the Setup menu an alignment scan can be initiated using the Scan Length soft key However from this menu the crystal temperature is not automatically set to a value calculated for the selected wavelength Instead the values in the user set fields are used Soft Keys Next Field moves the highlight box between the various fields so the field variable can be changed using the up down push buttons steps um toggles the second field from grating wavelength display default to stepper motor step count Use the up down buttons to change the contents Wavelength changes in steps of 0 001 um the stepper count changes in increments of 1 if the up down buttons are pressed momentarily or by 10 if held down this is useful for large step changes Loop On Off toggles the servo loop on default and off Scan Length brings up the Scanning Coarse Length menu once the scan has begun It is displayed so its progress can be monitored Back returns control to the Diagnostics menu If the loop is ON there is output power the grating is set to a position appropriate for the installed optic set and the temperature that is set in the Manual Control menu will be interpreted as
163. unami the height adjust locking nuts on all the feet are tight Routing mirrors drift Verify the mirrors are properly seated inside the routing mirror assemblies and that the assemblies are securely fastened to the table The Tsunami wavelength is This can be caused by a combination of the two previous conditions Also drifting check that the single plate birefringent filter has been installed in the Tsu nami Temperature offset is close to a Reduce the temperature offset 1 or 2 region of instability Opal Opal cavity is misaligned Optimize Opal output by adjusting M and M and if you have to check the cavity alignment Refer to Chapter 5 Installation and Alignment Uncontrolled lab environment Check and correct for any conditions that might cause vibrations or perturba causes external vibrations per tions of the optical table e g air conditioning fans or noisy water lines Ver turbations ify there is little change in room temperature and humidity lt 5 Also ensure there is not a direct flow of air from a register or air vent onto the table Unstable pump power Optimize Tsunami output for a TEM mode and stable output power Refer to your Tsunami user s manual 8 4 Service and Repair Symptom Noisy Opal output Possible Causes Corrective Action Incorrect temperature offset Set the temperature offset for optimum Opal performance Refer to Chapter 6 Operation Adjust Temp Menu for info
164. ure outlined in Opal Alignment 1 3 um Optic Set Aligning the Opal Cavity earlier in this chapter However do not perform the final step to adjust the focus of P This completes the conversion to the 1 3 um optics set 5 28 Chapter 6 Warning m General Operation Operation The PCMCIA memory card in the Opal controller uses a 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 f the battery dies the data is lost and a full sys tem recalibration is required Appendix D explains how to change the battery Please read The Menus section starting on page 6 8 and familiarize your self with the functions and controls of each menu The menu descriptions are presented in a logical sequence according to the flow chart in Figure 6 2 Familiarize yourself with the system menu structure and its controls and parameters before attempting to run the Opal for the first time Only then if you wish to operate the Opal remotely via the optional serial RS 232 or parallel IEEE 488 interface familiarize yourself with the corresponding commands and queries listed in Appendix E as well as the syntax structure that is used to send and receive these commands and queries To avoid duplication this section refers only to the front panel controls Operating the system remotely is very similar On a
165. w Note When changing optics all operating parameters temperature scan wavelength etc which were being used are automatically stored and the operating parameters which were last used for the new optics set are automatically recalled Soft Keys Next Field moves the highlight box between the various fields so the field variable can be changed using the up down push buttons Full Align brings up a series of help menus that step through an Opal mechanical alignment then initiates a scan Scan Length brings up a menu that displays the status of the scan Main Menu returns to the Main menu Opal fs Synchronously Pumped Optical Parametric Oscillator Scan Length Menu SETUP Preparing to scan length Desired xtal temp is 63 6 Actual temp is 13 996 The Scan Length menu reports to the Setup menu When it appears it dis plays a notice that the length scan is about to begin and also shows the desired temperature and actual temperature of the crystal in percent of total range Based on the Opal wavelength chosen in the Setup menu the con troller determines the proper temperature for the crystal The Actual temp displayed changes until it reaches the desired temperature then the system begins the cavity length scan If the two temperatures already match or are very close it may appear that this menu is skipped and the Scanning Coarse Length menu is immediately brought up At this point the scan begins an
166. wavelength noted on the crystal test summary If it is not the same operate the Opal at the specified wavelength of the other set 2 Go to the Setup menu and verify the installed optic set and the pump wavelength are correct 3 Press the button under Scan Length and note the Desired X tal Temp then abort immediately Set the temperature of the crystal to that noted in the previous step 5 If the crystal is tested at 1 50 um and you are operating at 1 30 um subtract 10 from the temperature value at 1 50 um If the crystal is tested at 1 30 um and you are operating at 1 50 um add 10 a Go to the Adjust Temp menu and select the Temp Table Shift then use the Next Field button to select the Shift field b Adjust the offset to change the temperature to the correct Temper ature required The percentage difference can be calculated from the temperature noted in Step 3 6 Follow the standard Opal alignment procedure Aligning the Opal Head 1 Turn on the Millennia pump laser At the same time turn on the Tsu nami and the Opal electronics modules and allow them to warm up and stabilize for at least 15 minutes 2 Danger The Millennia and Tsunami pump lasers are Class IV High Power Laser Radiation Lasers Always wear proper eye protection and follow the safety precau tions in Chapter 2 Laser Safety 2 Verify the output of the Millennia pump laser meets specifications
167. wavelength of 775 nm is used for the 1 18 to 1 34 um signal wavelength range while 750 nm is employed for shorter wave lengths For the 1 3 um optics set it is necessary to employ the intracavity prism pair to achieve a net negative intracavity GVD to produce short near transform limited output pulses Signal 400 r M NS 350 Power mW 0 1 00 1 25 1 50 1 75 2 00 2 25 2 50 Wavelength um Figure 3 5 The Opal Tuning Curves Control Electronics Idler Output js Waveplate Pi Pump Input Servo ut Wavelength r ZM NG Wa Monitor fers Idler oe H NEE Splitter pet Signal Output PEE gt Residual Pump Output M Motor controlled Output Coupler Figure 3 6 Opal Cavity Beam Path 3 4 LLL Description Configuration For the 1 35 to 1 60 um signal wavelength region 810 nm is used for the pump wavelength Since the LBO crystal exhibits negative GVD in the sig nal wavelength range it is not necessary to use prisms for the 1 5 um optics set The Opal cavity configuration is shown in Figure 3 6 The vertically polar ized Ti sapphire input pump beam first passes through a half waveplate which can be used to rotate its plane of polarization Several flat mirrors P P and P3 then direct it to a focusing mirror P4 where the pump beam is focused to about a 50 um spot size in the Brewster cut LBO crystal The latter is mounted on a thermo electric heater The cavity consis
168. which the system can be easily controlled The buttons are used to select and change system parameters fields that are displayed in the menu Up down push buttons located to the right of the screen increase or decrease the value of the selected field The system parameters and functions displayed depend on which menu is selected at the time Screens include menus for e System set up save and recall e Automated scan modes e Manual operation e Diagnostics Typical items displayed are settings for e Optics set Pump wavelength e Signal output wavelength e Idler output wavelength e Relative output power e M motor relative position e PZT relative position e Scan parameters e Crystal temperature e Grating position e Servo status e System offsets e RS 232 and IEEE 488 parameters Purging the Cavity The Opal is sealed so that it can be purged with nitrogen gas Purging the cavity not only eliminates the typical problems associated with dust and airborne contamination but also prevents tuning discontinuities caused by oxygen and water vapor Purging of the latter is imperative for operation between 1 33 and 1 48 um and when operating below 1 18 um see Figure 3 7 The Model 3910 regulator filter purge unit provided with the Tsunami laser can also be used to dry and filter bottled nitrogen gas for use in the Opal D escription Transmittance 1 100 1 200 1 300 1 400 1 500 Wavelen
169. y to re calibrate the wavelength monitor grating or use it in conjunction with the directions given in Appendix C to perform a complete calibration This procedure requires the use of an external mono chromator to measure the output signal wavelength To perform the recom mended day to day calibration simply run Scan Length from the Setup menu This automatically re calibrates the system for day to day use Next Field moves the highlight box between the Set actual wavelength field and the Zeroth Order at field Once selected use the up down push buttons to change the values Set Cal uses the values entered in this menu to calibrate the grating posi tion The new calibration is permanently stored in the system until changed by pressing this button again Main Menu returns to the Main menu 6 21 Opal fs Synchronously Pumped Optical Parametric Oscillator 6 22 Chapter 7 Maintenance The condition of the laboratory environment and the amount of time the Opal is operated affects its periodic maintenance schedule The coated surfaces of the elements forming the cavity the output coupler high reflector prisms fold and focus mirrors and crystal surfaces are easily contaminated Do not allow smoking in the laboratory the optics stay clean longer Con densation due to excessive humidity can also contaminate optical surfaces This is particularly true for the LBO crystal If the head cover is left in place there is li

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