下载手册
Contents
1. AK 4 5a 2 E 4 5b 8 SEK 4 5c a b c FIG 4 5 DIAPHRAGM POSITIONS A RIGHT B CENTRAL C LEFT OKRE 7 Jd 4 10 OPERATION During transportation or when system is not used correct position of diaphragm is left extreme position In this position optics is safe from getting dirty covering with dust and accidental damage during transportation Basic rules of an optical path adjustment When the position of the laser beam is being corrected the spot position on2. SN Harris Interval LINEAR MEASUREMENTS Beam Strength Hour Minus Second F sb sf s Change Stop No Time vae E pee eoe ome mra e 1 183114 0 001884 44 9897 2236 2185 2183 2173 Environmental 2 193125 0 001936 44 9897 2234 2183 2181 2171 3 183135 0002012 44 9835 2230 2181 2189 2169 Re iv Humidity 4 193145 00020808 44 9897 2227 2179 2187 21 67 position 0 000000 lt 5 19 31 55 0 002208 44 9897 2224 2178 2185 21 66 6 183205 0 002246 44 9837 2222 2175 2184 21 64 4 v Pressure 989 7 193215 0 002265 44 9897 2219 21 74 21 82 21 62 v Air Temp 22 M um C Save to file End Recording v 21 Average temp wil We T3 272 ECES AE PASO Record 0 100 Resolution 10 nm 80 60 40 20 0 20 40 60 80 100 Reset Position Main Menu FIG 5 9 RECORDING DATA MODE FIRIN Pressing End Recording finishes the data recording The results can be saved with the choice of Save to file In presented fig 5 9 the example of
3. 1k 11 7hm 2 9 PRINCIPLES OF OPERATION Edien lpp
4. 90 CO 4 0 45 90 90 Reference reflector Two perpendicular linear polarizations Moving reflector Two mode laser Polarizing splitter gt fp frequency resulting from the Doppler effect baig B vertical polarization horizontal polarization sin os Photodetectors D gt polarization 45 B polarization 45 Pulse counter FIG 2 2 THE BLOCK DIAGRAM OF AN INTERFEROMETER WORKING ACCORDING TO THE HOMODYNE METHOD EYEAOG E 3E CES ESL D Perpendicular linear polarizations Polarizer 0 C C Polarizer 45 PRINCIPLES OF OPERATION Polarizer In the heterodyne method shown on figure 2 3 two different laser frequencies are used Theref
5. Linear positioning measurement The linear positioning measurement is the most advanced option of linear measurements It is most common form of measurement performed on the machines The system measure linear positioning accuracy repeatability and backlash by comparing the position displayed on a machine s readout with the true position measured by the interferometer In order to start measurements option Main Menu should be activated and Positioning should be chosen On the screen will appear a window linear positioning as presented on fig 5 6 5 6 5 8 LINEAR MEASUREMENTS Laser Position mm Beam Strength Target Position mm Positioning 02 11 05 Point Xa Xr Point number Mai
6. JJ aj RE f FR 2 4 L1 L1 L2 L2 L1 2 11 PRINCIPLES OF OPERATION Interferometer Base point Reflector Null point 8 mN i Laser head NNN S Li Lo Interferometer Base point Null point l pony Reflector Laser head fASNAAAASAASSASA L Lo The correct deployment of the optical components for reducing a dead path error FIG 2 4 AN ILLUSTRATION OF A DEAD PATH ERROR 466 R
7. 5 10 LINEAR MEASUREMENTS Option View serves to switching on or off a panel Target Position Error Table and to switching on drawing on the graph of measuring points from all cycles active cycle is drawn using solid line but remaining cycles are illustrated using only points If system is ready to work then on the screen appear two digital displays and gauge of measuring signal level On the upper display measured value is shown on the bottom display value of target position whic
8. gt 7 4 7 1 gt gt gt SD 74 FLATNESS MEASUREMENTS ma File Edit Measurement Hell Automatic mnm RARE IIS 0 2 sekl Flatness Axis 2 2888 eseee e BEEBBe Be888 BERRSSESSRRER ERE ERS SHER Srogtness Emorum BS ESE SERES e Li 0 22 18 2 2 E 5 25 3 32 E 3 4 s eine Ds 0 08 um Czas oczekiwania 3 5 s BENE i Flatness Plot End Point Fit Method FIG 7 4 CHANGING AXIS IN FLATNESS MEASUREMENT Optical path adjustment in the axis 1 A 1 The straightness measurement in the axis 1 is done with the optical components and in the way described in Chapter 6 Straightness measurements 1 6 xx ARR eT FIR ET Fo Optical path adjustment in the axes 3 6 8 HI 3 6 8 During flatness measurements in the axes 3 6 and 8 an additional beam directi
9. Examination of linear positioning of machine consists of at least 2 measuring cycles In every cycle the measured machine will move the retro reflector for programmed distance fore Avers and back Revers After each shift the machine should stop for a time at least one second The measured distance by the laser system 1s saved in the table of results After at least two series of measuring cycles statistical calculations can be executed and execute report from examination is prepared In order to get the final report press a button Report Using buttons Remove and Add it is possible to change the measuring cycle in which accidental error is suspected The screen of the computer after pressing the button Report is presented on fig 5 7 LINEAR MEASUREMENTS 2
10. 5 8 LINEAR MEASUREMENTS POSITIONING RAPPORT Machine BFK130 Serial No AxisX File Name BFK130X1 dt2 Acquisition date 01 11 08 15 41 14 Current date 02 11 06 15 08 15 Measurement System LSP 30 Compact LASERTEX Results Measurement Conditions Norm NMTBA Accuracy Air Temperature E 23 3 C Forward Reverse n r o Bidirectional Material Temperature 19 4 C Repeatability Humidity 36 Forward Reverse Bidirectional Pressure 980 hPa Backlash Mean Max 8 9 10 18 19 20 21 2 23 24 Forward Mean 1 3 Sigma Reverse Moan Reverse Mean 3 Sigma Bidirectional Mean 3 Sigma X Reverse Data Points Forward Data Points Signature FIG 5 8 LINEAR POSITIONING REPORT LINEAR MEASUREMENTS Recording mode The long term changes of the length of machine axes under changes of temperature condition may give the information about thermal properties of the machine This kind of measurements called Recording mode may be chosen by pressing RECORD button on the Display screen This switches the system into the mode of the data recorder The time interval of the records could be programmed from the computer by setting a required value
11. I Warnings Rep Ls Although the laser measurement system LP30 3D was design to be used in harsh environments the following conditions must be met e The laser head must not be put near strong magnetic fields e The head should not be unscrewed from its base and if it is it may not be put on a heat sink e g thick metal plate e The head must not be thrown or dropped e Keep the optical components clean and avoid scratching them e When the optics is dusted clean it with pure alcohol e Do not use the system outside its work conditions LP30 WFE WEEER o 1 2 INTRODUCTION BOCK TU ETE PRINCIPLES OF OPERATION 2 PRINCIPLES OF OPERATION Basics of laser displacement measurements Dis
12. Laser beam Reflectors Laser head NN Machine s movement axis FIG 2 5 THE BEAM UNADJUSTMENT AS A CAUSE OF A COSINE ERROR R 1k Hg f ID DEOR WHE The only method of eliminating the cosine error is a proper laser beam adjustment procedure performed before the measurement 2 13 PRINCIPLES OF OPERATION Abbe error An Abbe error occurs when during measurements the measured part does not move perfectly parallel with the axis of the measuring system The sloping of the reflector is the greater the longer is the distance between the axis of the measurement and the axis of movement This distance is called An Abbe offset Only the movements in the axis of the measurement are important see fig 2 6 An Abbe error may be avoided only when there are no angular movements of the retro reflector in the axis of the measurements 2 6 Axis of Reflec
13. 5 7 Laser Mea surement System Linear Positioning BFK130X dt2 Plot FIG 5 7 LINEAR POSITIONING RESULTS The positioning parameters are presented on the graph In the right side panel Results is found on which results of statistical calculations and a norm according to which calculations were executed are presented The norm can be chosen from a list After choosing a new norm the results are recalculated 5 14 LINEAR MEASUREMENTS Under the graph buttons used for the change of the axis scale Axis Scale automatic scaling or assignment minimum and maximum values choosing of parameters shown on the graph Parameters report printout Print and return to looking through the measuring cycles Previous Menu are found Example of linear positioning report of CNC machine in axis is presented on fig 5 8
14. RLI ILI II X 47 FIG 4 7 START POSITION OF ADJUSTMENT 4 14 OPERATION 6 Move the moving element of the machine together with the attached optical element in opposite extreme position Diaphragms on IL1 and RL1 and of laser head place in position Adjustment 6 IL1 RLI EJ 2 a 2 d FIG 4 8 ADJUSTMENT POSITION A AND WORK POSITION B HEMA Ca B 7 Regulate the tripod height and level of the laser head by means of a sphere joint The laser beam has to fall on upper hole in interferometer diaphragm and after passage by the hole must be found within diaphragm area of the retro reflector The laser head should be placed horizontally for horizontal axes control it on the level indicator 7 8 Using regulating elements of the laser head find
15. Measurement can be driven in an Automatic option or in a Manual Capture option In automatic version the system oneself recognizes the moment of stop the value of target point the direction of movement and the number of series For correct work of automatic option below rules should be used 1 Time of stop duration in measuring point at least 1 second 2 Vibrations of machine not too large 5 12 LINEAR MEASUREMENTS D 1 2 If vibrations are too large System does not capture points then the option Manual Capture should be switched on in the menu Measurement After choosing the Manual Capture option on the bottom of the screen appears an additional button Manual Capture Capture of the measuring point takes place by pressing this button or pressing the button on the impulse switch
16. 6 4 0 3 AANGULAR MEASUREMENTS lp dLaser Measurement System Display Beam Strength Unit lem Environmental Measurement Parameters id 0 000 e Humidity 90 Start position joe E Sga Pressute Material Air Temp 200 D Al h 22 6 lum C Average temp 20 0 Rozdzielczo 10 nm Environmental r Record Reset Position Main Menu FIG 6 4 ANGLE DEVIATIONS MEASUREMENT SETUP Cffa If 2 5 00 c t After display reset the system is ready to measurements If the retro reflector is moved to a new point the display shows the value of the angle deviation in relation to the first point It is also possible to measure change of the angle deviation in the same point if the inclination of retro reflector changes WNBA a WARS AME T o WAR CH ae 2 1 1 BOE S SEAN BF Me ANAT Yo A E 8 BE fi FEAL o t T PA S e e ex UU t FE d Straightness measurements The straightness measurements are performed moving the retro reflector base t along a straight line In order to get the correct measurement the straight
17. Attention Remember that the position when the interferometer touches the retro reflector can serve only to adjust Be sure that during measurements in extreme nearest measuring position the retro reflector does not touch the interferometer because it can be a source of measuring errors lu TEE dB TP MAA BON a AE A AFE RE MEP d 4 17 LINEAR MEASUREMENTS 9 LINEAR MEASUREMENTS Measurement set Linear measurements are the most often used measuring option Using this option it is possible to measure Linear displacement Velocity of moving element Linear positioning Vibrations see Chapter 8 Measurements may be executed in three mutually perpendicular measuring axes X Y Z Change of a measured axis will demand displacements of optics X Y 2 5 1 LINEAR MEASUREMENTS Required measuring set a computer a las
18. 5 6 7 8 9 10 100 11 6 7 10 FLATNESS MEASUREMENTS Optical path adjustment in the axes 2 and 4 2 4 Similar to previously described during flatness measurements in the axes 2 and 4 two beam directing mirrors ZK1 are used The difference is that the angle of the second mirror usually differs from 45 The way of using them is shown on Figure 7 7 272
19. 0 02 ppm Other errors In some conditions a noticeable error may be caused by the electronic part of the interferometer As the electronics is used mainly for counting the errors may be associated either with miscounting some pulses are not counted or with miscalculating the calculations are made with finite precision PRINCIPLES OF OPERATION Summary of laser measurement system errors In order to show which of the errors influence the accuracy of a laser measurement system the most an exemplary calculation of errors on a lm long steel machine is shown on figures 2 7 and 2 8 Different scales of the charts should be taken into account 2 7 2 8 Im GLaser Environment O Cosine O Dead path W Electronics EI Unlinearities I Thermal drift 0 1 2 3 4 5 6 7 8 9 10 Positioning
20. 100 If from some reasons will not be possible to move the retro reflector base before the capture moment the measurement should be repeated from the beginning point and possibly the measuring interval should be enlarged 0 7 AANGULAR MEASUREMENTS lp dLaser Measurement System Straightness Lawal dt4 zy xe File Edit Measurement Help Cin ane asf MS Straightness Error um CDU ee 20 25 35 3s 40 4s E 5 60 30 ss 9o 35 400 ate is Ds 110 81 um Czas oczekiwania 3 5 s BENE Main Menu Angular Method Base Length 100 mm FIG 6 6 RESULT OF STRAIGHTNESS MEASUREMENT int Fit Method m To perform the measurement manually the option Measurement automatic in option Measurement should be switched off The measurement is started by pressing Start The Capture of the measuring points can be done from the computer keyboard or by pressing the remote Strobe button Ea
21. n P T H WY STE nr py Edien 1 10 P 0 613 0 00997 T An Nr py 1 2 8775 107 P di 14 0 003661 T 4 An 3 033 10 H e0057627 7 5 From the above equations one may obtain the refraction coefficient dependences on T P and H in usual conditions T2293K P 1000hPa H 50 T P ME T 293K P 1000hPa H 50 en 0 93 10 oT K at 0 27 t oP hPa on 0 96 DPA aH It is worth to notice that the most critical parameter is the temperature because its change influences the coefficient n more than changes in the pressure and much more than changes in the humidity n n PRINCIPLES OF OPERATION The accuracy of laser interferometers Errors caused by the environment The most impotent source of errors in machine geometry measurements is the temperature or
22. Measurement Range ju Resolution Accuracy Distance 0 30m 0 01 um 0 001 um 0 41 um m Velocity 0 0 3 m s 0 1 m s 0 25 um s 0 1 Angular 0 3600 arcsec AP 0 04 arcsec 0 2 96 Straightness measurement 0 12m 0 02 hm for 100 mm 1 with angular optics base 100 0 12m 0 02 um for 100 mm 0 5 Flatness Vertical range 2 mm base 2 100 Straightness measurement 0 3m 0 5 um with Wollaston prism 1 0 5 0 15L HARRE Wollaston Bi ai Wi Straightness measurement 3D 0 10 m 0 1 um 342 x L um L in meter 1000 arcsec JF 0 4arcsec JF 1 1 5 arcsec Squareness Rotary measurements t5 0 04 arcsec WH 0 2 L axis length in meters For resolution 1 nm Inm 7 1 TECHNICAL DATA Laser head Zeeman HeNe laser with frequency Laser type e stabilization 2 amp A fe OG ga Heating time Approx 20 min 20 Wavelength vacuum XK CAF Short time stability Distance between out and ingoing beam 12 7 mm Laser head dimensions 60x60x245 mm Net weight 1500 g Class 2 La
23. 8 9 10 zs 1002577 11 6 In the case of the measurements in the axis 2 the path adjustment procedure is the same as described above The only difference is that the first mirror as not needed is not used 2 7 13 STRAIGHTNESS MEASUREMENTS 3D STRAIGHTNESS MEASUREMENTS 3D Straightness squareness measurement highlights any bending component or overall misalignment in the guideways of a machine This could be a result of a wear in guideways a collision or poor machine foundations The straightness squareness errors will have a direc
24. 7 3 Optical path adjustment in the axis 1 Fi 1 HW 7 5 Optical path adjustment in the axes 3 6 8 3 6 8 a 7 5 Optical path adjustment in the axes 5 and 7 5l 5 7 HELE WIFE sess 7 8 OPTICAL PATH ADJUSTMENT IN THE AXES 2 AND 4 2 4 7 11 STRAIGHTNESS MEASUREMENTS 3D see 7 1 VIBRATION MEASUREMENTS 050000050555 7 1 MEASUREMENTS Jlll ed nn dn en ed de ed 7 3 TECHNICAL DA TA 000000 7 1 SYSTEM SPECIFICATIONS 0 7 1 LASER HEAD MO ne eek ie ee sO a ede A We ea deas s 7 2 SYSTEM WORK CONDITIONS R LEA ae eee nne 7 2 POWER SUPPLY Ee AERE AE A T ER AE A AR 7 2 POINTEREAGEE DI dn EEA EE E EEE EEE 7 3 ENVIRONMENT COMPENSATION 7 3 INTRODUCTION 1 INTRODUCTION Laser measurement System LP30 3D is a two frequency interferometer for inspection of machine tools and calibration of coordinate measuring machines CMM Its small size and low weight simplify transportation and make the instrument especially useful for service applications Software version for Windows 9x NT 2000 XP and automation of measurement process make the interferometer easy to use Software and reports are compliant to ISO DIS 230 and PN 93 M55580 standards Following standards are included ISO 230 2 European VDI DGQ 3441 German NMTBA USA BSI BS 4656 Part 16 British and PN
25. ZK1 2 45 7 7 FIG 7 7 SET OF THE OPTICAL COMPONENTS USED IN STRAIGHTNESS MEASUREMENTS IN THE AXES 2 AND 4 2 4 7 11 FLATNESS MEASUREMENTS The diaphragm on the laser head set to the Adjustment position The first beam directing mirror ZK1 set 45 to the laser beam coming out from the head The position of the laser head should be regulated in a way that the beam reflected from the first mirror runs parallel to the axis 3 and falls on the second beam directing mirror The second mirror is set 45 to the first one Changing the position and the angle of the second mirror directs the reflected beam along the axis 4 in a way the beam is parallel to the axis Place the angle interferometer in magnetic holder of the second mirror and set it in the optical path Set the diaphragm on the angle interferometer to the Adjustment position Change the position of the head so that the beam falls in the middle of upper interferometer s diaphragm Set the diaphragm on the angle retro reflector to the Adjustment position Moving the retro reflector along the axis change the position of the head so that the beam passing through the interferometer falls also in the m
26. 11 For precision adjustment when the straightness measurement will be carried on use electronic adjustments Switch screen of the display to Adjustment mode Using adjustment screw set two crosses blue and green to the centre of the screen Blue cross corresponds to reference beam while the green one to measuring beam see Fig 4 9 11 Display 4 9 4 16 OPERATION ri ZI mad Beam Strength TTT change Environmental Measurement Parameters F A n Humidity 30 Distance Axis X Start position 0 000000 lt e ete 994 hPa v Adjustment Sign 4 10 TE Material Air Temp 20 0 sl p Ts s Mie Steel s um C 40 4 3 t t df 1 t t 4 A Average temp 20 0 7 Resolution 100 nm 100 T T T T 100 80 60 40 20 0 20 40 60 60 100 Record Main Menu Reset Position FIG 4 9 CORRECT ADJUSTMENT OF OPTICAL PATH 12 Reset displayed position using Reset button on the display System is ready to work 12
27. 1 2 LP30 4 2 Display 4 4 4 3 OPERATION p gLaser Measurement System Main Menu S lg x Display Positioning Velocity Angular Pos Straightness Flatness FIG 4 2 MAIN MENU If the program is started before the Power Supply is turned on or the Power Supply is not connected properly to the computer on the monitor an error window with No connection or Power Supply Off line will appear fig 4 3 In this case close the program check the connection and or the supply of the Interferometer POWER diode on and restart the program 4 3 OPERATION Q Mo connection or Power Supply OFF Could not open Com port Check COM port settings FIG 4 3 ERRORS THAT MAY OCCUR DURING SOFTWARE LOADING If the Interferometer is connected to the wrong COM in case serial port is used instead of USB then an error window with Could not open COM port Check COM port settings
28. 0 3 The influence of the outside conditions on the measurement accuracy According to equation 1 an interferometer s unit of measure in length measurement is laser s wavelength From definition nec D f 2 a wavelength depends on laser s frequency f and the speed of light v in the measuring path If the measurement is done in vacuum then v c 3 10 m s The speed of light in a medium other than vacuum e g air water is lower and is described as 1 4 f v BUR DU Bae FEL v c 3 108 m s Where n a refraction coefficient 2 7 PRINCIPLES OF OPERATION Normally the refraction coefficient n is a complex variable or even a tensor but for less accurate calculations it is simplified to a constant The air coefficient depends mostly on the pressure P temperature T and humidity H The dependence nrp for the air was empirically determined by Edien and is described as
29. 100 Environmental ECU EU When measurements are executed with automatic compensation of the atmosphere parameters and compensation of the basis temperatures Environmental Compensation Unit ECU switched on one should Place the Environmental Compensation Unit ECU on the machine in the vicinity of the laser beam Place the sensors of the basis temperature along the measured axis on the machine basis Measurements executed without automatic compensation are referred to normal conditions temperature 20 C pressure 1016 hPa humidity 50 4 8 OPERATION RD CECUO 20C 1016 hPa 50 Adjustment of the optical path An adjustment of the optical set up should be conducted in option Display It c
30. Temperature sensor Time constant Net weight Temperature of material entered from keyboard With the use of 1 to 3 temperature sensors 1 3 Pt 1000 in oil resistant casing Win SCH Pt 1000 5s 50 g Our products are subject to continuous further development and improvement Subject to technical changes without prior notice 7 4 ea
31. 5 7 During flatness measurements in the axes 5 and 7 two beam directing mirrors ZK1 are used The way of using them is shown on Figure 7 6 5 7 ZK1 7 6 Biz o FIG 7 6 SET OF THE OPTICAL COMPONENTS USED IN STRAIGHTNESS MEASUREMENTS IN THE AXES 5 AND 7 5 7 7 8 7 9 FLATNESS MEASUREMENTS The diaphragm on the laser head set to the Adjustment position The first beam directing mirror ZK1 set 45 to the laser beam coming out from the head The position of the laser head should be regulated in a way that the beam reflected from the first mirror runs parallel to the axis 3 and falls on the second beam directing mirror The second mirror is set 45 to the first one Changing the position and the angle of the second mirror direct the reflected beam along the axes 5 or 7 in a way the beam is parallel to the axis Place the angle interferometer in magnetic holder of the second mirror and set it in the optical path Set the diaphragm on the angle interferometer to the Adjustment position Change the position of the head so that the beam falls in the middle of upper interferometer s diaphragm Set the diaphrag
32. z2 2 1 PRINCIPLES OF OPERATION LAE TRU aNLHEVI E BOER LR Fe CLA 2 1 4 2 d Where CHE N number of pulses CK PASO light wavelength Leg Reference reflector Moving reflector Coherent light source ofY fb frequency resulting from the Doppler effect FIG 2 1 THE MICHELSON INTERFEROMETER EE EM T Ef Reference reflector Coherent light source Moving reflector Detector Doppler effect PRINCIPLES OF OPERATION The construction of real interferometers The main disadvantage of Michelson interferometer results from the fact that the detector cannot determine whether fp is negative or positive thus from the measurements the displacement of the moving reflector without the sign is obtained Currently there are widely used two methods that allow getting also the direction of the movement Depending on the number of light frequencies wavelengths used in the interferometer the first is called homodyne one frequency and the second heterodyne two frequencies method In the homodyne meth
33. line will appear To change the number of used COM port choose option Config fig 4 4 COM C47 sig HIE USB EA COM COM COM Config CIEL 4 4 Getting basic Information from the System Atfter proper software loading choose option Display The laser System will be preheated The beam intensity the green indicator on the screen will appear and disappear The speed of changes will become smaller due to the increase in the temperature of the laser system cover The measuring system is ready for an adjustment of the optical arrangement of the laser path Display RE E G 4 5 OPERATION vm Measurement System Display E of x Beam Strength OTT Change Environmental 4 __ Measurement Parameters F Humidity 32 Distance AxisX start position 0 000000 Iv Pressure 1003 9 hPa Adjustment Sigm 4 Material Resolutio
34. 298898292538 20 40 6 80 100 120 140 160 160 200 220 240 260 20 300 320 340 360 30 400 420 440 460 480 500 Frequency Hz Measurement Main Menu FIG 8 4 EXAMPLE OF VIBRATION MEASUREMENT RESULTS What may be confusing in obtained results are different amplitudes of frequencies on the frequency diagram after changing from Distance to Velocity and to Acceleration fig 8 5 It happens so according to the theory from which results 8 5 Ean dd fa Evn Ep fa T Ean Where Ep amplitude of n th frequency when Distance is selected n 7 5 VIBRATION MEASUREMENTS Ey amplitude of n th frequency when Velocity is selected 1 n Ean amplitude of n th frequency when Acceleration is selected nm f n th frequency n FIG 8 5 DIFFERENT FREQUENCIES AMPLITUDES IN DEPENDANCE ON 7 0 10 TECHNICAL DATA TECHNICAL DATA System specifications
35. VIBRATION MEASUREMENTS The laser measurement system LP30 3D is capable of detecting machine vibrations in the frequency range from 0 to 500 Hz For these measurements an element set for linear measurements is used i e a PC computer a laser head with a power supply a stand Tripod magnetic holders one UM1 and one UM2 a linear interferometer IL1 and a linear retro reflector RL1 The Environmental Compensation Unit ECU and the temperature sensors do not have to be used The optical path should be adjusted as shown in Chapter 4 LP30 3D 0 500 AAA Hla oo PC C1 UML UM2 ILL RLI ECU 4 To obtain correct results it is necessary to select carefully the point where the retro reflector will be connected to the body of the measured machine If the point is chosen improperly then a multiple frequencies n f will be shown where n 1 2 on the FFT chart instead of a sought frequency f For that reason the retro reflector must not be in theses measurements used on the magnetic holder UMI It must be also remembered that the system measures vibratio
36. Parameters contains a few options Option Sign allows choosing whether enlarging distances between the retro reflector and the interferometer gives positive default or negative result on the display In the option Material one can choose the material from which a basis of a machine is made of the value of the thermal expandability coefficient of the basis is accepted for calculations of 4 7 OPERATION compensation Option User make it possible to enter any value of the thermal expandability coefficient In the panel Resolution one can change between high 10nm and low 100nm system resolution In higher resolution accepted movement velocity is strictly limited see Technical data chapter for details With the option Environmental the Environmental Compensation Unit ECU may be switched on or off From console of the computer one can switch off the external Environmental Compensation Unit ECU and enter the parameters of atmosphere by hand Sign T ae RU TP CBS B S Material User 10
37. error um m FIG 2 7 A CALCULATION OF ERRORS FOR A LASER MEASUREMENT SYSTEM WITHOUT THE COMPENSATION OF THE ENVIRONMENT 2 10 PRINCIPLES OF OPERATION GLaser Bl Environment O Cosine O Dead path W Electronics El Unlinearities Bl Thermal drift 0 05 0 1 0 15 0 2 0 25 0 3 Positioning error um m o FIG 2 8 A CALCULATION OF ERRORS FOR A LASER MEASUREMENT SYSTEM WITH THE COMPENSATION OF THE ENVIRONMENT 2 17 PREPARATIONS 3 PREPARATION To start the measurements using the Laser Interferometer LP30 3D software LP 30 3D should be installed on HDD of a PC computer The hardware requirements are Windows 9x NT 2k XP operating system CR ROM Pentium processor 90 MHz or better SVGA graphic card with minimum resolution 800x600 LP30 3D LP30 3D PC Windows 9x NT 2k XP 90 MHz SVGA 800 600 Software installation BUT BL To install the LP program on the PC computer put the CD disc LP30 3D into the CD ROM The program will be installed automatically LP30 ne LP
38. more exactly the change of the temperature of the measured machine For example if the machine s base is made of steel then the base s length increases 11 7hm when its temperature changes 1K It shows how important it is for very precise measurements to measure the temperature of the controlled part of the machine and to use it in readout corrections This is not a simple task for a few reasons but the most important one is that than when the machine operates there are temperature gradients on it That means that more than one temperature sensor is needed and that the more sensors are used the better accuracy can be achieved Moreover the shape of the measured part of the machine may absorb a part of the expansion of the material or the part may be built of materials of different expandability As was mentioned in the previous chapter the temperature influences the accuracy also as it changes the refraction coefficient of the medium the measurements are made in usually it is air but may be e g water An Edien equation was presented showing how the refraction coefficient of the air changes with the change of the air temperature pressure and humidity The errors caused by the change of the wavelength are less important than the mentioned above but they cannot be abandoned Roughly a lppm error i e lum m is caused by the air temperature change of o 1K the air pressure change of 4hPa and the air humidity change of 30
39. mouse leftward we cancel increasing The graph can be printed or saved to file when we choose from upper menu File and then suitable option i e Save Save as Print CER ZARA BOG SK NAA EI E BH IBI EMA ESE FP PEE LINEAR MEASUREMENTS EI Laser Measurement System Velocity FIG 5 4 VELOCITY GRAPH WINDOW An example graph of changes of the linear displacement velocity of a machine table in one axis is presented on fig 5 5 5 5 5 6 LINEAR MEASUREMENTS Wykres Predkosci Ayah SS Pr dko mms Czas s FIG 5 5 EXAMPLE GRAPH OF CHANGES OF LINEAR DISPLACEMENT VELOCITY Program
40. ruler against which the retro reflector base is pushed should be fastened or fixed on the measured axis or surface The measurement lateral surface of the retro reflector base must always be tangent to the ruler see fig 6 5 6 4 ANGULAR MEASUREMENTS 6 5 FIG 6 5 AN EXAMPLE OF OPTICAL COMPONENTS SETUP IN STRAIGHTNESS MEASUREMENT Required measuring set a PC computer a laser head with a laser interferometer power supply a stand Tripod two magnetic holders UM1 or UM2 a Environmental Compensation Unit ECU SM1 sensors of basis temperature T1 T2 T3 an angular interferometer IK1 an angular retro reflector RK1 on a support base P100 mm a remote control Strobe UMI UM2 ECU SM1 Tl T2 T3 1 IK1 P100 RKL EAER o 6 5 AANGULAR MEASUREMENTS The
41. straightness measurement is performed keeping the angular retro reflector against the ruler and moving at intervals of about 100 mm and measuring its angle deviation Before performing the measurements you should mark reference positions at intervals of 100 mm on the leading ruler or on the examined surface The use of a ruler with a scale is recommended The straightness measurement is performed in the option Straightness chosen from Menu Main fig 6 6 100 KAARE M 100 6 6 lp dLaser Measurement ot Straightness E inl Eile Edit Measurement Hel ae ET Move Retrare Je ektor 14 15 16 17 18 Distance cm Czas oczekiwania 3 5 s Is rd B Main Menu FIG 6 6 STRAIGHTNESS MEASUREMENT WINDOW CH Ae REM E ff A 6 6 ANGULAR MEASUREMENTS The measurement can be done in an automatic mode standard arrangement or in a manual mode with manual triggering of measuring points In the automatic mode capturing of the measuring points takes place after a selectable time delay The time between capturing the measuring points is used t
42. 1 basis Environmental Compensation Unit ECU sensors T1 T2 T3 an angle interferometer IK1 an angle retro reflector RK1 on a P100 base and two beam directing mirrors ZK1 The element set for the flatness measurements is shown on fig 7 2 FIG 7 2 FLATNESS MEASUREMENT KIT IK1 RK1 ON P100 BASE AND ZK1 7 2 FLATNESS MEASUREMENTS Adjustment of optics for the flatness measurements The measurement of flatness consists of the measurements of deviations from straightness made along 8 axes The measurement axes are set on a measured surface as shown on figure 7 3 On this figure are shown also directions of measurements in the axes and margins that must be kept during measurements 8 7 3 7 3 Set Measurement Axis q x Checked Axis geeeeeesessesen C Axis2 C Axis3 C Axis 4 C Axis 5 C Axis 6 C Axis 7 C Axis 8 o X Cancel Help FIG 7 3 THE MEASUREMENT AXES The measurements of deviations from straightness are made with angular optics as described in Chapter 6 Straightness measurements Depending on the measurement axis a different set of optical components is used and the adjustment of the optical pa
43. 30 CD CD ROM el 3 1 PREPARATIONS Components of the Laser Interferometer The number of required components depends on the type of measurement to be performed Standard set for linear measurements includes 1 1 x Laser head Laser Interferometer 1 x Power supply Laser Interferometer Power Supply 1 x Tripod stand 1 x Environmental Compensation Unit ECU SM1 1 x Laser head to power supply cable 2 x Magnetic holder UM1 x Linear interferometer IL1 x Linear retro reflector RL1 ee o gv OWE gae de ger 3 x Basis temperature sensor T1 T2 T3 1 x RS232C cable gt 11 1x Manual Strobe cable to trigger measurements remotely See fig 3 1 on the next page for pictures of the elements of the standard set 1 1 2 1 3 1 4 1 ECU SMI 5 1 6 2 UMI 7 1 IL1 8 1 RLI 3 2 PREPARATIONS 9 3 T1 T2 T3 10 1 RS232C 11 1 3 1 Add
44. 93 M55580 Polish Extremely high technical parameters of the interferometer allow using it as an absolute length reference in scientific and calibration laboratories for precision positioning systems for upgrade of length measurement systems etc LP30 3D Windows 9x NT 2k XP ISO DIS 230 PN 93 M55580 1S0230 2 KRY VDI DGQ 3441 NMTBA BSI BS 4656 16 PN 93M55580 1 1 INTRODUCTION Safety considerations The Laser Interferometer LP30 3D is a Safety Class I product designed and tested in accordance with international safety standards It is also a Class II Laser product conforming to international laser safety regulations The instrument and the manual should be inspected and reviewed for safety markings and instructions before operation LP30 3D
45. Data Record is 5 9 T o 5 18 ANGULAR MEASUREMENTS 6 ANGULAR MEASUREMENTS Measuring set for angular measurements The angular measurements performed by the laser interferometer system are used for straightness surface flatness and angular positioning of rotary tables Straightness measurements can be done in three mutually perpendicular axes X Y Z X Y 2 FIG 6 1 SETUP FOR ANGULAR MEASUREMENTS IN X AXIS CX 6 1 AANGULAR MEASUREMENTS Change of measuring axis will demand displacements of angular optics figures 6 1 6 2 and 6 3 FIG 6 2 SETUP FOR ANGULAR MEASUREMENTS IN Y AXIS ae FIG 6 3 SETUP FOR ANGULAR MEASUREMENTS IN Z AXIS 6 2 ANGULAR MEASUREMENTS Required measuring set a computer a laser head with an interferometer power supply a stand Tripod two magnetic holders UM1 or UM2 a Environmental Compensation Unit ECU SM1 sensors of basis temperature T1 T2 T3 an angular interferometer IK1 angular retro reflector RK1 mounted on P100 mm base remote control Str
46. EAM w Hn Cosine error If the laser beam is not parallel to a measured axis of a machine i e the optical path is not properly adjusted then a difference between the real distance and the measured distance occurs This error of misalignment is known as a cosine error because its magnitude depends on the angle between the laser beam and the axis of the machine fig 2 5 If as a reflector a flat mirror is used then the beam must be perpendicular to it If the machine changes its position form point A to point B then the beam stays perpendicular to the mirror but moves on its surface The distance measured by the laser interferometer Lims will be smaller than the real distance Ly according to 2 12 PRINCIPLES OF OPERATION AEM KAD RR FS GR A HL as AHN fA BE CA 25 A B Lums Ly Lims Lu cos 6 The above equation is valid also when as a reflector a corner cube is used
47. Laser Interferometer LP30 3D User manual Laser Interferometer LP30 3D LP30 3D Z ROE FAX User manual FLA F At CONTENTS AELOD OLOA M LONE ic E EE E E E EE 1 1 SAFETY CONSIDERATIONS 0 1 2 WARNINGS 225 E E E T S S 1 2 PRINCIPLES OF OPERATION sssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss 2 1 THE RULES OF LASER DISPLACEMENT MEASUREMENTS RN 2 1 THE CONSTRUCTION OF REAL INTERFEROMETERS 2 3 THE INFLUENCE OF THE OUTSIDE CONDITIONS ON THE MEASUREMENT ACCURACY HS de A E E E EAE EE ENE A E EA 2 7 THE ACCURACY OF LASER INTERFEROMETERS 05 2 9 Errors caused by the environment Jf AE EIU PE oscccscececscsvesessssssesssesvevesssesvenesssessesesesesesneasseseesens 2 9 2 10 A cosine error OGG CREE vvccccvscecscevscesscesscescescesscescesscesscesscesscesscescesseesseesscessessscesseesseessessasesseesseesecs 2 12 An Abbe error PI WE 2 14 A laser stability error RO TS EES ia Rin nie oe ARIA aa Gi o 2 15 Other errors FLA TEE RR 2 15 A summary of laser measurement system errors BEWARRE sss eee 2 16 PREPARATIONS 000005555 3 1 SOFTWARE INSTALLATION oes ceccecceccesccesceccescesccescescesccaccsscescesecsecsscscesecsecseesceaecsscsceaceasereseess 3 1 THE LASER INTERFEROMETER SYSTEM ELEMENTS HOE FNN PRESE 3 2 OPERATI
48. MENTS Adjustment process 4 12 OPERATION 1 In the option Display in the PC program choose type of measurement which will be done and axis along of which measurements will be carried On the screen will appear a drawing showing recommended arrangement of measuring elements at the chosen type of measurement 2 Linear interferometer IL1 and linear retro reflector RL1 should be mounted on magnetic holders UM1 UM2 Regulating elements of the laser head should be placed in central positions to assure maximum range of regulation 3 Choose which from the optical elements will be moved retro reflector RLI or interferometer IL1 and attach both with magnetic holders one to a moving element of the machine second to an element in relation to which displacement will be measured for example the retro reflector may be fasten to a moving element and the interferometer to a motionless table Remember that relative linear displacement between the retro reflector and the interferometer is measured Attention It is inadmissible to place one of optical elements i e RL1 or IL1 outside the machine on an additional stand the system measures then also displacements of the machine in relation to the stand 4 The moving element of investigated axis should be moved in closest position to the laser head position 5 Place the interferometer optics IL1 and the retro reflector RL1 on the axis of mo
49. ON PAE ERE LEE 4 1 PREPARING THE INTERFEROMETER TO WORK RN 4 TURNING THE SYSTEM ON 4 3 GETTING BASIC INFORMATION FROM THE SYSTEM M 7 amp SE 3k Ey EZ fei sh isses 4 5 ADJUSTMENT OF THE OPTICAL PATH laaasasasesisssssnssororororoiririnininininintororaarinininisininrnrarororonenes 4 9 BASIC RULES OF AN OPTICAL PATH ADJUSTMENT sues 4 11 ADJUSTMENT PROCESS RR 4 12 LINEAR MEASUREMENTS 5550500050 5 1 MEASUREMENT SET 0 5 1 LINEAR DISPLACEMENT MEASUREMENT 4 5 4 LINEAR DISPLACEMENT VELOCITY MEASUREMENT pp 5 4 CONTENTS Velocity graph dz NM NETT 5 5 LINEAR POSITIONING MEASUREMENT 5 8 RECORDING MODE 0 5 17 ANGULAR MEASUREMENTS 48 BE E amp ss ss sse see see ssesssssssssssssssssssssssssssssssssssssssssssssssssssssss 6 1 MEASURING SET FOR ANGULAR MEASUREMENTS 6 1 MEASUREMENT OF ANGLE DEVIATIONS pe 6 3 STRAIGHTNESS MEASUREMENTS 0 6 4 FLATNESS MEASUREMENTS JF rii BE BU EE cccccscsccsssscsssscssscscsssscessssessscsssssssessssessscessssssssssersses 7 1 PREPARA PIONS S arta LasetertietaLasa pen rtequ ER edat et EE a grise bir P ond Rt 7 1 ADJUSTMENT OF OPTICS FOR THE FLATNESS MEASUREMENTS
50. a position in which laser beam passes through both upper apertures in the diaphragms placed on the interferometer and the retro reflector 4 15 OPERATION 8 9 Switch the diaphragms on ILI and RLI in a position of work 9 1 M RLI 10 Using the regulating elements of the laser head adjust the position of laser beams on the diaphragm of laser head Two return beams should exactly cover each other an entrance hole on the front panel of the laser head If this is necessary gently correct the position of the IL1 Shift the diaphragm on the laser head to the position Work The level of the measuring signal the green indicator on the screen of the computer should have value not less than 80 during translocation of the moving element along the whole path 10 ILl 80
51. also counts an average velocity from a visible range on the graph Possible 1s also presetting of minimum and maximum values for measured axis Clicking left mouse button on selected axis or clicking right mouse button within the area of the graph appears a menu from which we choose proper axis On the screen appears a window of scaling of axes Velocity scale and Time scale We can place scaling automatic or set maximum or minimum values Program makes possible also saving the velocity graph and then loading it for example to Word editor To save graph to file we should click with right mouse key within the area of the graph Popup menu will appear menu from which we should choose Copy to clipboard instruction The choice of the speed unit 1s also possible from menu Edit we should choose option Config where we can set the velocity unit 5 7 LINEAR MEASUREMENTS DRE MA BeAr PE 4 A AE a Ee NSE PY E A C EG PP Word
52. an be done during laser head heating Final check should be made when the system is ready to work The Laser Head should be firmly attached to the tripod The tripod should not touch a machine as it may cause vibration of the laser head and the optical path Turn special attention not to move the legs of the tripod during the measurements because it will cause shift of elements of the optical path and the necessity of repetition of the adjustment process The arrangement of the tripod helps to adjust the optical path Inspection of the level of arrangement can be made using level fastened on the tripod and on the laser head The diaphragm of the laser beam is found on the front panel of the laser head The diaphragm can be placed in three positions Right extreme position fig 4 5a Adjustment the laser beam goes out through opening in the diaphragm about 2 mm diameter Central fig 4 5b Measurement from the laser head goes out beam about 8 mm diameter Left fig 4 5c extreme position in which the exit of the beam from the laser head is completely closed 4 9 OPERATION Display
53. ch time after the movement of the retro reflector base of about 100 mm measuring point should be captured After capturing the last point press Stop The results of the measurements may be saved to a file or printed according to the setup in File menu 100 0 8 FLATNESS MEASUREMENTS 7 FLATNESS MEASUREMENTS Preparation The flatness measurement is performed on the basis of straightness measurements of eight axes After measurement values have been collected a flatness 3D map is drawn fig 7 1 8 3D 7 1 FIG 7 1 AN EXEMPLARY SURFACE FLATNESS MAP 7 1 FLATNESS MEASUREMENTS Required measuring set consists of a PC computer a laser head with a power supply a Tripod stand two magnetic bases UM1 and or UM2 a Environmental Compensation Unit ECU SMI
54. crometers are displayed 3D a 7 2 STRAIGHTNESS MEASUREMENTS 3D 8 1 Straightness Measurements Horizontal Axis lt gt int 3
55. d FIG 8 2 RESULTS OF STRAIGHTNESS MEASUREMENTS ARRIER The accuracy of the straightness measurements depends on the precision of the adjustment of the measured axis It is recommended that the position of the crosses during adjustment as seen on the Display screen procedure to be set to the center of the screen zero position Vibrations of the base where the tripod is placed and air density fluctuations are the causes which will affect the accuracy of the measurement When the required accuracy of straightness measurement for the tested machine is not satisfactory it is necessary to perform measurements with the use of angular optics or with the Wollaston 7 4 STRAIGHTNESS MEASUREMENTS 3D prism which gives more accurate results but needs more time for setup and optical path adjustment 7 5 VIBRATION MEASUREMENTS 9
56. er head with a power supply a stand Tripod two magnetic holders UM1 or two UM2 a Environmental Compensation Unit ECU SM1 sensors of basis temperature T1 T2 T3 a linear interferometer IL1 a linear retro reflector RL1 remote control Strobe option UML UM2 ECU SM1 Tl T2 T3 IL1 RL1 REPS ALT OTE FIG 5 1 SET UP FOR LINEAR MEASUREMENTS IN X AXIS X LINEAR MEASUREMENTS FIG 5 2 SET UP FOR LINEAR MEASUREMENTS IN Y AXIS Y FIG 5 3 SET UP FOR LINEAR MEASUREMENTS IN Z AXIS Z 5 3 LINEAR MEASUREMENTS Linear displacement measurement When one want to prepare the measurement System for the measurement of a linear displacement electric connections and adjustment of the optical path see chapter 4 must be carried out When the laser system is ready to work green LED light on the forehead of the laser head Next it is necessary to check optical path i e whether the measuring signal reached at least 80 on the entire axis The measurements now can start A measuring unit mm um a number of Co 66 significant positions on a display a meas
57. f the atmosphere and temperatures measured by three base temperature sensors Average temperature of the base measured by three sensors is also presented CECU A The Measurement windows shows basic information about the performed measurement With the left button the type of measurement can be changed The right is used for choosing measuring axis At every changing of measuring option i e distance speed angle straightness and changing of measuring axis i e X Y Z a picture shows how to setup the optical elements Click with the left mouse key on the picture to get detailed information on how to setup the optical elements help online x Y Z Panel
58. h is read from data points table or appointed automatically Under the displays from the left side there is presented a graph on which the results of measurements are shown From the right side Error Table is found Under the graph button Start beginning measurement and button Main Menu allowing to enter to Main menu are placed In the bottom parts of the window a status bar can be found on which there is presented a configuration of the positioning measurements In the first field 5 11 LINEAR MEASUREMENTS information about method of measuring points capture is found manual automatic In second field information whether measuring points originate from list or are marked automatically is shown The next field informs about number of cycles in series number of cycles executed one after one if not active is option Stop after every cycle In the last field information about activity of opti
59. he measurement manually or automatically LP30 3D USB PC 4 1 OPERATION USB ECU TPH 6 T1 T2 T3 4 6 5m E Strob T1 T2 T3 ECU RS232C Laser Head FIG 4 1 ELECTRIC CONNECTIONS OF THE LP30 3D LP30 ESD 4 2 OPERATION Turning the system on Switch on the device according to the following instructions 1 Switch on the power switch on the Laser Interferometer Power Supply 2 Start LP30 program on a computer When the main menu appears at the computer monitor fig 4 2 choose option Display fig 4 4
60. iddle of the retro reflector s diaphragm After changing the positions of the diaphragms on the interferometer and on the retro reflector to Working positions check if the return beam falls in the middle if measuring opening in the head Do the check moving the retro reflector along the axis Corrections if needed can be made both changing the head or the interferometer position 10 Set the diaphragm on the laser head to Working position and check if the level indicator on the display shows around 100 1 1 Now the straightness measurements as described in Chapter 6 can be made FLATNESS MEASUREMENTS 1 2 ZK1 45 3 45 3 4 BP 4 5 6 7
61. itional elements for angular measurements are 1 1 x Angular interferometer IK1 2 1 x Angular retro reflector RK1 3 2 x Beam directing mirror ZK1 4 1 x Rotary table SO1 1 1 IK1 2 1 RKI 3 2 ZK1 4 1 SO1 3 3 PREPARATIONS Fig 3 1 The elements of the standard set OPERATION 4 OPERATION Preparing the interferometer to work The Laser Interferometer LP30 3D is supplied from autonomous power supply Laser Interferometer Power Supply connected via USB to the PC Before starting the measurements place the laser head Laser Interferometer on the Tripod stand and connect it with the LP power supply Connect cable from laser head to socket on the front panel of the Laser Interferometer Power Supply Connect the USB cable to the front panel of the Power Supply and to the PC Notebook Connect the Environmental Compensation Unit ECU TPH to 6 pin marked METEO socket on front panel of the Power Supply Temperature sensors T1 T2 T3 connect to 4 pin sockets placed on the front panel To 6 pin socket marked STROBE should be connected a source of strobe signal Strobe signal may be produced by a pulse switcher 5 m cable with a pulse switcher is in standard set or by any other devices Strobe input is used to trigger t
62. l Reference reflector Two perpendicular linear polarizations Moving reflector Nonpolarizing f2 splitter Zeeman laser Two circular f polarizations f Polarizing splitter lt fb frequency resulting from the Doppler effect fa fi f fi F fp fp 21 C B vertical polarization ae horizontal polarization E path Counter uu Me Measurement path Sesame FIG 2 3 THE BLOCK DIAGRAM OF AN INTERFEROMETER WORKING ACCORDING TO THE HETERODYNE METHOD Subtractor Photodetector The heterodyne method gives correct results only when fp does not exceed the difference between the laser frequencies i e f f In reality that difference resulting from the Zeeman effect is about IMHz This fact limits the maximum available velocity of the measuring arm in one direction to 0 3 m s The next disadvantage of the heterodyne method is that two frequencies must be used for measurements while in the homodyne method the second may be used for measuring e g a second axis 2 6 PRINCIPLES OF OPERATION F2 F1 1MHz
63. m lym m IK 4hPa 30 Dead path error A dead path error is an error associated with the change in environmental parameters during a measurement This error occurs when some part of the light path a dead path is not included in the temperature both air and base pressure and humidity compensation The dead path of the light path is a distance between the optical interferometer and the base or the null point of the measuring position L on figure 2 4 Let the position of the interferometer and the retro reflector do not change When there is a change in the air temperature pressure or humidity then the wavelength changes on the whole path length Li L2 The path length changes also when the temperature of the base changes But the correction system will use the correct wavelength only on the length L2 and will correct only this length The correction will not be made on a dead path L4 In this way the laser system will move the base point 2 10 PRINCIPLES OF OPERATION The higher is the distance between the interferometer and the base point the higher is the dead path error This error is especially important in laser interferometers where the interferometer is build up in a common casing with a laser head because it is then very difficult to reduce it
64. m on the angle retro reflector to the Adjustment position Moving the retro reflector along the axis change the position of the head so that the beam passing through the interferometer falls also in the middle of the retro reflector s diaphragm After changing the positions of the diaphragms on the interferometer and on the retro reflector to Working positions check if the return beam falls in the middle if measuring opening in the head Do the check moving the retro reflector along the axis Corrections if needed can be made both changing the head or the interferometer position 10 Set the diaphragm on the laser head to Working position and check if the level indicator on the display shows around 100 11 Now the straightness measurements as described in Chapter 6 can be made FLATNESS MEASUREMENTS 1 2 ZK1 45 3 45 3 5 7 4
65. made both changing the head or the interferometer position 9 Set the diaphragm on the laser head to Working position and check if the level indicator on the display shows around 100 10 Now the straightness measurements as described in Chapter 6 can be made L 2 45 3 IK1 4 5 6 7 8 9 TER 100 10 6 FLATNESS MEASUREMENTS Optical path adjustment in the axes 5 and 7
66. measurement starts after pressing the Measurement button Then appears the Measurement Window see fig 8 3 that shows two progress bars the upper blue one shows the progress in measurement the lower green one shows progress in sending data to the computer The measurement is in progress when the upper bar is in the range of 0 100 it lasts approx 12s FFT 8 3 gt 8 3 EMA ORO 7 3 VIBRATION MEASUREMENTS 0 100 12 ly Laser Measuremen t System Analiza czestotliwosciowa dd d lolx Frequency Hz FIG 8 3 VIBRATION MEASUREMENT WINDOW When both the measurement and the transmission are done the measurement results are presented on the time diagram and its FFT analysis on the frequency diagram fig 8 4 The results can be saved printed or exported men
67. n 100 nm Air Temp 22 38 C Q iv Average temp anil TZ T3 Record FIG 4 4 OPTION DISPLAY On the Display screen there are four panels Panel containing the digital result of the measurement the measuring signal level indicator and the buttons for changing the number of displayed Digits and for changing Units Quantity of significant digits on display may be changed with the use of buttons T 4 pressing button with an inscription Change changes measurement unit on the display In the upper left corner there is an icon making link to Microsoft Excel if installed Running this link allows to register measurement in Excel cells by each STROBE button press Change 4 6 OPERATION Microsoft Excel Excel Panel Environmental where measuring data obtained from the Environmental Compensation Unit ECU are shown On the screen there are shown temperature pressure and humidity o
68. n Menu FIG 5 6 LINEAR POSITIONING WINDOW In this window appears upper menu which consists of options File Edit Measurement View Help In option File are found instructions making possible reading measuring data from disc saving data on disc and printout of measurements results Option Edit allows to enter measured machine parameters preview of measurement results in every cycle of positioning and an edition of positioning points when option Target Points from List from menu Measurement is active FERS ff ALES ER Option Measurement includes the options connected with the process of measurement Start beginning of measurements Stop break of measurements 5 9 LINEAR MEASUREMENTS Dynamic choosing this option activates dynamic mode of linear positioning measurement Manual Capture choosing this option causes that for measuring points we can get measured value of displacement by pressing a button Manual Capture or by pressing pulse switcher of Strobe If this option is not active point
69. n only in the axis of the optical path Any vibrations in perpendicular axes do not influence the measurement see fig8 1 An example of a properly attached retro reflector is shown on fig 8 2 7 1 VIBRATION MEASUREMENTS asyf f FFT n 1 2 UMI 8 1 8 2 Interferometer IL1 Vibrations Vibrations not important important FAN W Retroreflector RL1 ut FIG 8 1 VIBRATION MEASUREMENT IN DIFFERENT AXES 7 2 VIBRATION MEASUREMENTS FIG 8 2 EXAMPLE OF PROPERLY ATTACHED RETRO REFLECTOR CET H Til x Be NaN BID Measurements After adjusting the optical path and choosing FFT option from Main Menu a window as shown on fig 8 3 appears The most important parts of this window are time diagram frequency diagram and radio buttons on the right side Before measurements a machine data may be set Edit gt Machine Data The
70. ng mirror ZK1 is used The way of using it is shown on Figure 7 5 FEW 3 6 8 ZK1 75 7 5 FLATNESS MEASUREMENTS FIG 7 5 THE SET OF THE OPTICAL COMPONENTS USED IN STRAIGHTNESS MEASUREMENTS IN THE AXES 3 6 AND 8 3 6 8 1 The diaphragm on the laser head set to the Adjustment position 2 The beam directing mirror ZK1 set 45 to the laser beam coming out from the head 3 Place the angle interferometer IK1 in the measured axis 4 Set the diaphragm on the angle interferometer to the Adjustment position 5 Change the position of the head so that the beam falls in the middle of upper interferometer s diaphragm 6 Set the diaphragm on the angle retro reflector to the Adjustment position 7 6 FLATNESS MEASUREMENTS 7 Moving the retro reflector along the axis change the position of the head so that the beam passing through the interferometer falls also in the middle of the retro reflector s diaphragm 8 After changing the positions of the diaphragms on the interferometer and on the retro reflector to Working positions check if the return beam falls in the middle if measuring opening in the head Do the check moving the retro reflector along the axis Corrections if needed can be
71. o move the retro reflector about a distance of 100 mm The time interval should be used in dependence from practices of a person leading the measurements It is suggested to set the time on 10 s and to decrease it if needed An arrangement of the time interval may be done by pressing keys on the computer screen The retro reflector base P100 should be placed at the beginning of the examined axis close to the interferometer After the Start button is pressed one should wait on capturing the first measuring point Then one should move the retro reflector base of about 100 mm and to wait on the next point capture Announcements shown on the computer screen make the measurement easy After capturing the last measuring point press Stop 100 10 s P100
72. obe option Auxiliary equipment used in the angular measurements is two mirrors ZK1 mounted on supports serving to reflect the laser beam necessary to measurements of the surface flatness a rotary table SOIT controlled by step motor used to angular positioning measurements UMI E UM2 ECU SM1 T1 T2 T3 1 IK1 2E P100 RKl X TIDJDGAT CTE o ZRELE EPS BE ZK1 SO1 Measurement of angle deviations Preparations to measurements are similar to those described in the previous chapter The measurements are executed in Display mode Select Angle as type of measurements and select the measured axis fig 6 4 As a default when the retro reflector is bent towards the laser head direction the measured value is positive It is possible to change the sign in the option Parameters Change of sign
73. od shown on figure 2 2 as a coherent source of light a linearly polarized laser is used If it is two mode laser i e it generates two wavelengths than one mode must be cut off with the use of a properly set polarizer The polarising splitter splits the light beam from the laser into two beams polarized vertically 90 and horizontally 0 The former is directed to the measurement arm and the latter to the reference one The frequency of the beam in the measurement arm changes with the movement of the moving reflector The polarization of the reflected beams is changed to circular with the use of a A 4 waveplate After 0 and 45 polarisers two signals shifted in phase are obtained The phase shift is 90 when the measurement arm moves towards the laser and 90 when it moves from the laser fp ce TEM 2 3 PRINCIPLES OF OPERATION 2 2
74. ollaston For squareness measurement one additional optical element is necessary the optical square master The straightness of the movement is measured by measuring of the position of the reference and position of the measuring beams returning to the laser head 3D measurements offer unique possibility of measurements of straightness in two dimensions in one measurement This significantly shortens the measurement time Besides the 3D straightness measurement are done at the same time when the positioning measurements After finishing the positioning cycle one can view the results of the straightness just by pressing Straightness on the positioning screen It is also possible to measure the straightness in Straightness option in the main menu For 3D measurements select 3D method of measurement from the Measurement menu or from the Config menu on the main screen The straightness measurement software procedure is the same like for straightness measurements described in ANGULAR MEASUREMENT section In Fig 8 1 the print screen made during the measuring process is presented The automatic option of the measurement has been selected In the left black rectangle see the position of the retro reflector in mm is displayed while in the upper and lower black rectangle the horizontal and vertical shift in mi
75. on Stop after every cycle is presented To execute the linear positioning measurement program has to know the target position in which it has to make measurement and to count deviation These can be automatically defined in the first measuring cycle on a condition that distances between points are marked with accuracy to full millimetre The positioning points can be also written or counted after marking an option Target Points From List After activating this option the positioning points can be defined in any accuracy
76. or STOP Distance cm Straightness Measurements Vertical Axis 224 um Straightness Error um abc Distance cm Latency 7 0 s 7 PERE gt Main Menu 3D End Point Fit Method FIG 8 1 PRINTSCREEN OF STRAIGHTNESS MEASUREMENT The result of the measurements is presented in Fig 8 2 The upper trace shows the straightness for the horizontal plane and the lower one the straightness of the vertical plane Parameter D represents the straightness error End point fit method was chosen for plotting the result and for calculating of the straightness error 7 3 STRAIGHTNESS MEASUREMENTS 3D 8 2 D TES Measurement System Straightness b3 dt4 File Edit Measurement Help Straightness plot Horizontal Axis a a A on o Straightness Error um 140 130 120 110 1 00 90 80 70 60 50 40 30 20 10 0 Distance cm Ds 38 10 um Straightness plot Vertical Axis JE Straightness Error bm 4A eo 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 Distance cm Ds 85 55 jum Start lap End Point Fit Metho
77. ore a two frequency laser is needed Zeeman laser A two mode laser is not suitable for the heterodyne method interferometer because the difference between f and f is usually too high for an electronic counter The output beam of a Zeeman laser consists of two circularly polarized beams one polarized leftward and the second rightward A M4 waveplate changes circular polarization to linear The main difference between the two methods described here is that in the heterodyne one the beam frequency in reference arm differs from the beam frequency in the measuring arm The detection path is also different the measurement is performed by subtracting frequencies of reference and measuring arms 2 3 CZECH Fl F2 M4 2 5 PRINCIPLES OF OPERATION
78. placement measurements with the use of a laser interferometer allow obtaining the accuracy of a displacement of 0 4 ppm in air and 20 nm in vacuum The interferometer was first built by A A Michelson in 1881 The simplified schematic of the interferometer is shown on fig 2 1 Coherent light beam falls on a semi transparent mirror This mirror splits the light into two beams The first beam goes to the reference arm and reflects from the reflector Z the second goes to the measurement arm and reflects form the reflector Z2 The reflected beams meet again on the detector Because these beams come from the same coherent source they will interfere When the moving reflector is being displaced the frequency of the reflected beam in the measurement arm changes The detector counts the frequency difference between reflected beams fp see fig 2 1 The measured value of the displacement is calculated according to 0 4ppm 20nm 1881 2 1 Z1
79. s are captured automatically program detects the moment of machine stop Target Points From List after choosing this option on the screen appears a window for edition measuring points in which we write or count distance value for positioning points If this option is not active then the positioning points are marked automatically in first measuring cycle Stop After Cycle if this option is active program breaks the measurement after realization of a measuring cycle and if it is not active number of cycles set in configuration is executed Change Given Values setting this option gives possibility to change an earlier defined distance value of a measuring point during the measurement process Before point capture appears a window in which can be written new distance value whereupon marked are only places after comma what causes that it is not necessary to write all distances
80. ser product according to PN Safety class 91 T 06700 PN 91 T 06700 2 System work conditions Temperature range 10 35 C Humidity range 10 90 Power supply Voltage 90 230 VAC 50 60 Hz 35 W during heating Power 10 W work TPF 7 2 TECHNICAL DATA PC interface Type RS 232C USB Data rate 57 600 bps RS 232 Environment compensation Wavelength compensation Manual Environments parameters entered from keyboard Automatic With the use of the Environmental Compensation Unit ECU Parameters of the Environmental Compensation Unit ECU compensation Air temperature Em Range 0 40 C Accuracy 0 1 C Pressure Range 940 1060 hPa Accuracy 1 hPa Humidity Range 10 90 96 Accuracy 10 96 Time constants Temperature 3 s Pressure 2s Humidity 30 s Dimension 050x55 mm Net weight 100 g 7 3 TECHNICAL DATA Material temperature compensation Manual Automatic
81. t effect on machine geometry and as the result on machining accuracy The assessment of the machine geometry is one of the most important actions required when machine is setup EL IE He EW t 8 Las Se TRI TS Bo NE do RY I ES SLR Ah WM PCB Fe DL a Fk Ro ARRE ER SL a JLP Ee eae LEM sen Alas ila A Blasi Ll ve The geometry measurements are one of the most time consuming measurements the commonly used Wollaston prism optics is expensive and very difficult to adjust Operation of the system with the Wollaston prism optics requires high skilled personnel There are three methods available for straightness measurement with angular optics with Wollaston prism and with 3D method Wollaston Wollaston 7 1 STRAIGHTNESS MEASUREMENTS 3D The method with the angular optics was presented in section ANGULAR MEASUREMENT The optics with the Wollaston prism is supplied optionally The method 3D of straightness measurement don t require any additional optics W
82. th is done in slightly different way All flatness measurements are done with one laser head position shown on Figure 7 3 7 3 FLATNESS MEASUREMENTS The flatness measurements are performed in the option Flatness chosen from the Main Menu After setting proper base length standard is 100mm and machine data Edit gt Machine Data and Edit gt Base Length the Measurement button should be pressed Than a measured axis should be chosen fig 7 3 and then the optical path should be adjusted see below After the straightness of a chosen axis is measured a next axis should be chosen Measurement gt New Axis fig 7 4 When all the axes are measured Flatness Plot button should be pressed The received flatness plot fig 7 1 may be saved printed or exported to a text file File gt Save File gt Print or File gt Export 6 EHAE NR 7 3 100 gt gt 7 3
83. the diaphragm of the interferometer the interferometer is placed closer to the laser head should be regulated with X stage and up down translation stage Z and up down translation of the tripod The spot position on the retro reflector diaphragm the retro reflector is far from laser interferometer should be regulated with angle adjustment in vertical and D angle adjustment in horizontal line The regulating elements of the laser head are presented in fig 4 6 In Fig 4 6 one can see the position of the laser head for Y axes measurement In this position the function of the regulating elements will change X 2Z a B 4 6 B 4 6 Y 4 11 a b Vertical Locking e ball joint i peu Stew ee ie wee Vertical axis Y movement axis Z d OPERATION Horizontal rotation B Vertical rotation a FIG 4 6 LASER HEAD ADJUSTMENT ELE
84. tor measurement pnuncrecr 010 OQ fel 9 o Oe 4 axis of Error movement FIG 2 6 AN ILLUSTRATION OF AN ABBE ERROR Cf LiRANZEA GED 2 14 PRINCIPLES OF OPERATION Laser stability error As was already mentioned in laser measurements the laser wavelength instability changes directly the readout from the interferometer e g a relative instability of the laser in the range of 1ppm 10 causes an error of Ium on every lm of a measured distance Therefore the laser instability error is important mainly in measurements in vacuum where a refraction coefficient is constant and when a low stability laser is used e g a semiconductor laser The stability of usually used in laser measurement systems HeNe gas lasers is 0 02 ppm so the stability error may be neglected lppm 10 1 m lum
85. u File With the use of radio buttons the type of input data may be chosen i e whether amplitude of Distance Velocity or Acceleration is important In the frequency diagram not only the amplitude of vibration frequencies may be displayed but also their phase and real and imaginary part of the vibration The check buttons in the bottom right of the window allow to change the vertical scale of the frequency diagram to logarithmic and to eliminate a DC offset 8 4 FFT 7 4 VIBRATION MEASUREMENTS iH ER ELTA Ae o p dLaser Measurement System Analiza czestotliwosciowa dd dt7 a x File Edit Help Distance 5 Velocity Ii TM QUARE rmn Ul ae III i i Il i IN TURN Nh Il Amplitude Phase Real Imaginary Anpitude mme
86. ured axis a sign or and base s material may be chosen After resetting the display system is ready for measurements When the retro reflector is moved on the screen the displacement in relation to a starting point is displayed it is also possible to move the interferometer in relation to the standing retro reflector 4 LED 80 Linear displacement velocity measurement The arrangement of the optical path and the laser head should be the same as in the paragraph above The measurement of the linear displacement velocity is LINEAR MEASUREMENTS executed in option Display The t
87. vement Check the level indicator that the interferometer is in horizontal position Attach the retro reflector RL1 to the interferometer IL1 there is a special socket for this purpose in IL1 see fig 4 7 4 13 OPERATION 1 Display 2 ILI RLI UM1 UM2 3 RLI RFA ILI x b RLI ILIO 4 5 ILI RL11
88. ype of measurement should be changed on Velocity and a unit should be chosen m min m s After resetting the result on the display system is ready to the velocity of displacement measurement During translocation of the retro reflector the value of velocity is presented on the screen is possible to measure velocity moving the interferometer in relation to motionless the retro reflector Velocity graph The arrangement of the optical path and the laser head should be the same as in the paragraph above It should be activated Main Menu and chosen option Velocity Than a button Start should be pressed and the object which displacement velocity we investigate should be moved After moving stop button Stop should be pressed On the screen will appear a graph of velocity Clicking on a part of the graph and moving the mouse rightward we receive increasing of a selected fragment of the graph Clicking on a part of the graph and moving
Download Pdf Manuals
Related Search