User manual
Contents
1. Power Supply is not connected properly to the computer on the monitor an error 4 2 OPERATION window with No connection or Power Supply Off line will appear fig 4 3 To get rid of this error quit the program check the connection and or the supply of the Interferometer the POWER diode should be on x e No connection or Power Supply Off FIG 4 3 ERRORS THAT MAY OCCUR DURING SOFTWARE LOADING If the Interferometer is connected to the wrong COM than an error window with Could not open COM port Check COM port settings line will appear To change the number of used COM port choose option Config fig 4 4 Getting basic information from the system After 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 OPERATION cil x mm Measurement System Display 0 00000 Beam Strength Digts B Unit MM Environmental Measurement rParameters Humidity 32 96 Distance Axis X Start position 0 000000 lt V Pressure 1003 9 hPa Adjustment Sign Material Steel lt 11 7 s um ec Resolution 100 nm v Air Temp MAPS ONE iv Average temp AB Ab2. Corrections if needed can be 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 Optical path adjustment in the axes 5 and 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 FLATNESS MEASUREMENTS FIG 7 6 THE SET OF THE OPTICAL COMPONENTS USED IN STRAIGHTNESS MEASUREMENTS IN THE AXES 5 AND 7 1 The diaphragm on the laser head set to the Adjustment position 2 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 3 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 4 Place the angle interferometer in magnetic holder of the second mirror and set it in the optical path FLATNESS MEA SUREMENTS Set the diaphragm on the angle interferometer to the Adjustment position Change the position of the head so that the
3. 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 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 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 switcher Examination of linear positioning of machine consists of at least 2 measuring cycles In every cycle the measured machine will move the retro 5 9 LINEAR MEASUREMENTS 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 sy
4. Measurement Help Straightness Measurements Horizontal Axis 52 be um ae 53 m SM IUE 52 ans Bp gs dca 50 E gt Es Move Retroreflektor Y 48 ure E 47 UMass Z S 46 ra c Bas ec ae to point 3 or STOP e ations Distance cm Straightness Measurements Vertical Axis 227 4 u m Straightness Error um Distance cm Latency 7 0 s Main Menu 3D End Point Fit Method FIG 8 1 THE PRINT SCREEN OF STRAIGHTNESS MEASUREMENT 7 2 STRA IGHTNESS MEASUREMENTS 3D The result of the measurements are presented in Fig 8 2 The upper trace shows the straightness for the horizontal axis and the lower one the straightness of the vertical axis The parameter D represent the straightness error And point fit method was chosen for plotting the result and for calculating of the straightness error ba Laser Measurement System Straightness b3 dt4 l IOl xl File Edit Measurement Help Straightness plot Horizontal Axis 30r Se SES X o non O Cn A TT RO Straightness Error um i a 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 Distance cm Ds 38 10 um Straightness plot Vertical Axis Straightness Error um 1 40 130 120 110 100 90 80 70 60 50 40 30 20 10 0 Distance cm Ds 85 55 jun 3D End Point Fit Method FIG 8 2 THE RESULTS OF STRAIGHTNESS MEASUREMENTS The accuracy of the straightne
5. The choice of the speed unit is also possible from menu Edit we should choose option Config where we can set the velocity unit 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 LINEAR MEASUREMENTS Laser Measurement System Linear Positioning Laser Position mm Start Position mm 0 000 Bea Positioning 02 11 05 Error um Start Main Menu r pont genere 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 Option Measurement includes
6. additional optics For squareness measurement one additional optical element is necessary the optical square etalon 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 dimension in one measurement This significantly shortens the measurement time Besides the 3D straightness measurement are done at the same time when the positioning measurements 7 1 STRA IGHTNESS MEASUREMENTS 3D After finishing the positioning cycle one can view the results of the straightness just by pressing Straightness on positioning screen One could also measure the straightness in Straightness option chosen from the main menu For 3D measurements one have to choose the 3D method of measurement from the Measurement menu or from the Config menu on the main screen The straightness measurement software procedure are 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 was chosen In the left black rectangle one can see the position of the retro reflector in mm while in the upper and lower black rectangle the horizontal and vertical shift in micrometers Loser Measurement system 2 LPS iltz22 4 TS Fle Edk
7. basis temperature T1 T2 T3 an angular interferometer IK1 angular retro reflector RKI mounted on P100 mm base remote control Strobe 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 SO1 controlled by step motor used to angular positioning measurements Measurement of angle deviations Preparations to measurements are similar to those described in the previous chapter The measurements are executed in Display mode The type of measurements should be set to Angle and a suitable measured axis should be chosen fig 6 4 It is accepted that when the retro reflector is bent towards the laser head direction measured value is positive It is possible to change the sign in the option Parameters Change ofsign bh Laser Measuremen t System Display Beam Strength DT are Environmental Measurement Parameters 0 000 r Start position Humidity Angle Axis Y 7 s Sign Dieses 1013 ressure Material Air Temp 20 0 DEAE 2 gt HC BESERTI Average temp 20 0 lt Rozdzielczo 10 nm Environmental Record Reset Position Main Menu FIG 6 4 ANGLE DEVIATIONS M EASUREM ENT SETUP 6 3 ANGULAR MEA SUREMENTS After display reset the system is ready to measurements If the retro reflector is moved to a new point and on the screen the val
8. 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 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 Optical path adjustment in the axes 2 and 4 Similar to previous ly 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 FLATNESS MEASUREMENTS FIG 7 7 THE SET OF THE OPTICAL COMPONENTS USED IN STRAIGHTNESS MEASUREMENTS IN THE AXES 2 AND 4 1 The diaphragm on the laser head set to the Adjustment position 2 The first beam directin
9. lt la 100 4 Distance Velocity 5 Acceleration Sample saved Amplitude Phase Real Imaginary Log scale r pc Fon is yal Measurement Main Menu FIG 8 3 VIBRATION MEASUREM ENT 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 menu File With the use of radio buttons the type of input data may be chosen 7 3 VIBRATION MEASUREMENTS i e whether amplitude of Distance Velocity or Acceleration is important In the frequency diagram not only the amplitude of vibration frequencies may be display ed 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 lp Laser Measuremen t System Analiza czestotliwosciowa dd dt7 Help L 3 010 one Amplitude 01 1 o am Phase m 0102 e Tom Real dome ds Imaginary Same 1 ome on 1 r Log scale ame 0506 pc D 1 om gt o Ww w No Wo W0 29 29 ND XX WM IM IM M MO M NP 69 40 40 M M Freqenci pa Measurement Main Menu FIG 8 4 EXAMPLARY VIBRATION M EASUREM ENT RESULTS What may be confusing in obtained results are different amplitudes of frequenc
10. 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 2 2 PRINCIPLES OF OPERA TION 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 2 4 waveplate After 0 and 45 polarizers two signals shifted in phase are obtained The phase shift is 90 when the measurement arm moves to and 90 when it moves from the laser Reference reflector Two perpendicular linear polarizations f Moving reflector Two mode i laser Polarizing splitter iri x gt fp 1 4 fp frequency resulting from the Doppler effect fp72f B vertical polarization Polarizer 0 Polarizer 45 horizontal polarization Photodetectors E polarization 45 B polarization 45 sin Pulse counter FIG 2 2 THE BLOCK DIAGRAM OF AN INTERFEROMETER WORKING ACCORDING TO THE HOMODYNE METHOD In the heterodyne method shown on figure 2 3 two laser frequencies are used Therefore a two frequency laser is needed e g a Zeeman laser A two 2 3 PRINCIPLES OF OPERA TI
11. the axis 1 is done with the optical components and in the way described in Chapter 6 Straightness measurements Optical path adjustment in the axes 3 6 8 During flatness measurements in the axes 3 6 and 8 an additional beam directing mirror ZKI is used The way of using it is shown on Figure 7 5 7 4 FLATNESS MEASUREMENTS FIG 7 5 THE SET OF THE OPTICAL COMPONENTS USED IN STRAIGHTNESS MEASUREMENTS IN THE AXES 3 6 AND 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 IKI 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 5 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
12. 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 The accuracy of laser interferometers Errors caused by the environment The most impotent source of errors in machine geometry measurements is the temperature or more exactly the change of the temperature of the measured machine For example if the machine s base is made of steel than the base s length increases 11 7um 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 2 6 PRINCIPLES OF OPERA TION 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 coeffic
13. Laser Interferometer LP30 3D User manual www feanor com Laser Interferometer LP30 3D User manual CONTENTS INTRODUCTION porc M 1 1 SAFELY CONSIDERATIONS rta AA A Ae RAS RD 1 1 WARNINGS EEA E dd dede ne po e dios RES 1 2 PRINCIPLES OF OPERATION sssssssssssss ss essss cin id econ 2 1 THE RULES OF LASER DISPLACEMENT MEASUREMENTS cococononononononononononononononononononononenenenos 2 1 THE CONSTRUCTION OF REAL INTERFEROMET ERS occccccccccnnccccncnnnnnnnnononnnncnnnnnnononononccnnnnnnnnnn 2 2 THE INFLUENCE OF THE OUTSIDECONDITIONS ONTHE MEASUREMENT ACCUR ACY 2 5 THE ACCURACY OF LASER INTERFEROMETERS ocococononononononononononononononononononononononononononinenenos 2 6 Errors caused by the environment see 2 6 ACU path erro INN 2 7 A COSMETO qti e elt cc os e d Lt eae 2 8 An Abbe CV TON at e etie e AERE AA Rd dp ete adr iD epe DU Na 2 10 A laser stability error Osee cd 2 10 TCE IONS A A ab 2 11 A summary of laser measurement system errors 2 11 PREPARATIONS sussssssosssvebecnsiviveusnessousseveseeeabed iio 3 1 SOFTWARE INST ALLATION cscsssesscecececsessessensecececeesesseesansecececseseceusesececeesesscssenseeeeeseess 3 1 THE LASER INT ERFEROMETER SYSTEM ELEMENTS ococononononononononononononononononononononononononenonenos 3 2 OPERATION esmerada darai 4 1 PREPARING THE INTERFEROMETER TOW OR K 4 TURNING THE SYSTEM ON iere edere ee eta ere Eee dee er t
14. ON 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 1 4 waveplate changes circular polarization to linear The main difference between two described methods is that in the heterodyne one the beam frequency in reference arm differs from the beam frequency in the measuring arm A detection path is also different subtracting differential frequencies of reference and measuring arms does the measurement Reference reflector Two perpendicular linear polarizations Moving Nonpolarizing reflector splitter Zeeman laser Polarizing splitter gt fp frequency resulting from the Doppler effect Two circular f polarizations L fp 2f 2 B vertical polarization Photodetectors Measurement path Substractor FIG 2 3 THE BLOCK DIAGRAM OF AN INTERFEROMETER WORKING ACCORDING TO THE HETERODYNE METHOD horizontal polarization Reference path 2 4 PRINCIPLES OF OPERA TION 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 1MHz This limits the maximum available velocity of measuring arm in one direction t
15. OSINE ERROR The only method of eliminating the cosine error is a proper laser beam adjustment done before a measurement 2 9 PRINCIPLES OF OPERA TION An Abbe error An Abbe error occurs when during measurements the measured part does not move perfectly straight and there appear angular movements which cause sloping of the retro reflector 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 Axis of Reflector measurement o Q P Qu o a axis of Error movement FIG 2 6 AN ILLUSTRATION OF AN ABBE ERROR A 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 1um on every 1m of a measured distance Therefore the laser instability error is important mainly in measurements in vacuum where a refraction coefficient is 2 10 PRINCIPLES OF OPERA TION 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 las
16. SB interface 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 RS 232C USB cable to DB9 male socket on the front panel of the Power Supply The second end of the cable plug into the RS 232C socket of the computer or with additional RS323 USB interface to USB socket of the computer 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 control the moment of measurement either by hand or at dynamic positioning OPERATION Strob y T2 T3 ECU RS232C Laser Head FIG 4 1 ELECTRIC CONNECTIONS OF THE LP30 3D 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 If the program is started before the Power Supply is turned on or the
17. Z Change of a measured axis will demand displacements of optics Required measuring set a computer a laser head with a power supply a stand Tripod two magnetic holders UMI or two UM2 a Environmental Compensation Unit ECU SMI sensors of basis temperature TI T2 T3 a linear interferometer IL1 a linear retro reflector RL1 remote control Strobe option 5 1 LINEAR MEASUREMENTS FIG 5 1 SET UP FOR LINEAR M EASUREM ENTS IN X AXIS FIG 5 2 SET UP FOR LINEAR M EASUREM ENTS IN Y AXIS 5 2 LINEAR MEASUREMENTS FIG 5 3 SET UP FOR LINEAR M EASUREM ENTS IN Z AXIS Linear displacement measurement When one want 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 ie 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 KK 66 significant positions on a display a measured 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
18. and RL1 and of laser head place in position Adjustment 4 9 OPERATION y A s FIG 4 8 ADJUSTM ENT POSITION A AND WORK POSITION 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 8 Using regulating elements of the laser head find a position in which laser beam passes through both upper apertures in the diaphragms placed on the interferometer and the retro reflector 9 Switch the diaphragms on IL1 and RL1 in a position of work 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 96 during translocation of the moving element along whole path 11 For precision adjustment when the straightness measurement will be carried on use electronic adjustments Switch screen of the display to Adjustment mode Usi
19. ct 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 on 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 B angle adjustment in horizontal line The regulating elements of the laser head are presented in fig 4 6 In Fig 4 6d one can see the position of the laser head for Y axes measurement In this position the function of the regulating elements will changed 4 7 OPERATION a b c Vertical Horizontal Locking movement al ball joint Horizontal rotation B axis Z A movement Vertical Vertical axis Y movement rotation a axis Z Adjustment process 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 IL and linear retro refl
20. d vid ter it iLL lo l 4 Lb E VA aa Sal TEA SADA A VAUVUAVA NN ESES AVATA N K eke K K K AAA A A A G A Vay OAR AGN VNN VN V NN U NN 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 UMI and or UM2 a Environmental Compensation Unit ECU SMI basis Environmental Compensation Unit ECU sensors T1 T2 T3 an angle interferometer IK1 an angle retro reflector RK1 on a base P100 and two beam directing mirrors ZK1 The element set for the flatness measurements is shown on fig 7 2 FIG 7 2 THE ELEMENT SET FOR THE FLATNESS MEASUREMENTS IK1 RK1 ON P100 BASE AND ZK1 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 7 2 FLATNESS MEASUREMENTS directions of measurements in the axes and margins that must be kept during measurements Set Measurement Axis X Checked Axis C Axis 3 C Axis 4 C Axis 5 C Axis 6 C Axis 7 C Axis 8 Laser E X Cancel Help FIG 7 3 THEM EASUREM ENT AXES The measurements of deviations from straightness are made with angular optics as described in Chapter 6 Strai
21. e T3 Record Main Menu 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 Panel Environmental where measuring data obtained from the Environmental Compensation Unit ECU are shown On the screen there are shown temperature pressure and humidity of the atmosphere and temperatures measured by three base temperature sensors Average temperature of the base measured by three sensors is also presented 4 4 OPERATION Panel Measurement contains basic information about conducted measurement With the left button the type of measurement may be changed The right is used for choosing measuring axis At every changing of measuring option 1 e distance speed angle straightness and changing of measuring axis ie X Y Z a drawing suggesting the arrangement of the optical elements appears on the screen Clicking with left mouse key in the area of the drawing causes showing o
22. ector 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 4 8 OPERATION Attention It is inadmissible to place one of optical elements 1e 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 movement Check the level indicator that he 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 FIG 4 7 START POSITION OF ADJUSTMENT 6 Move the moving element of the machine together with the attached optical element in opposite extreme position Diaphragms on IL1
23. erence 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 A A a cuve 1 Where N number of pulses light wavelength PRINCIPLES OF OPERA TION Reference reflector Moving Z reflector l lt 7 eS 2 Coherent I light Phe OMS source fp frequency resulting from the Doppler effect Detector FIG 2 1 THE MICHELSON INTERFEROMETER 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 method shown on figure 2 2 as a coherent
24. ers is 0 02 ppm so the stability error may be neglected 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 A summ ary of laser measurem ent 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 1m long steel machine is shown on figures 2 7 and 2 8 Different scales of the charts should be taken into account PRINCIPLES OF OPERATION O Laser E Environment O Cosine O Dead path Electronics ElUrlinearities R Thermal drift 4 5 6 Positioning error um m FIG 2 7 4 CALCULATION OF ERRORS FOR A LASER MEASUREMENT S YSTEM WITHOUT THE COMPENSATION OF THE ENVIRONMENT El Laser Isl Environment O Cosine O Dead path Electronics El Unlinearities M Thermal drift 0 1 0 15 02 Positioning error um m FIG 2 8 4 CALCULATION OF ERRORS FOR A LASER MEASUREMENT SYSTEM WITH THE COMPENSATION OF THE ENVIRONMENT 2 12 3 PREPARATIONS PREPARATIONS 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 system CR ROM Pentium pr
25. f help on a theme of optical arrangement adjustment Panel 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 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 insert the parameters of atmosphere by hand 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 Measurement executed without automatic compensation are refe
26. 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 b Laser Measurement System Straightness Lawa1 dt4 J x Eile Edit Measurement Help 100 Staightness plor 0 2 sek GERD OWEI 8 8 CY AA YET n Ds 110 81 um Czas oczekiwania 3 5 s Start Main Menu reda Method Bas Langh M0 End Port Fa Method FIG 6 6 A RESULT OF STREIGHTNESS MEASUREMENT To make the measurement in the manual capture of the measuring points the Measurement automatic in option Measurement should be switched off 6 6 ANGULAR MEASUREMENTS The measurement begins by pressing Start The Capture of the measuring points can be done from the computer keyboard or by pressing the remote Strobe button Each time after the movement of the retro reflector base of about 100 mm measuring point should be captured After capturing the last point Stop should be pressed The results of the measurements may be saved to a file or printed in dependence of the options in the menu File FLATNESS MEASUREMENTS 7 FLATNESS MEASUREMENTS Preparations done on the basis of straightness 1S flatness measurement The d data a flatness map is drown ine ht axes From obta 18 measurements of e L Toe 27r 3 2a L r 444 Nn rit 177 nta 414 t
27. g 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 3 Changing the position and the angle of the second mirror direct the reflected beam along the axis 4 in a way the beam is parallel to the axis 4 Place the angle interferometer in magnetic holder of the second mirror and set it in the optical path 7 9 FLATNESS MEA SUREMENTS 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 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 pos
28. ghtness measurements Depending on the measurement axis a different set of optical components is used and the adjustment of the optical path is done in slightly different way All flatness measurements are done with one laser head position shown on Figure 7 3 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 2 Machine Data and Edit Base Length the Measurement button should be pressed Than a measured axis should be chosen fig 7 3 and than 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 7 3 FLATNESS MEASUREMENTS 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 bh Laser Measuremen t System Straightness 0 x Eile Edit Measurement Help Siaightness plat 0 2 se 09 P nom iames Ax 2 A 2 A 5 B M NW 4 paesi ml E Ds 0 08 um v 1 a t LI 19 2 18 Czas oczekiwania 9 55 Start Bun Flatness Plot reis Method Base Largh 100 n Erd Port Ft Matted FIG 7 4 CHANGING AXIS IN FLATNESS MEASUREMENT Optical path adjustment in the axis 1 The straightness measurement in
29. he 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 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 23 3 C Forward Reverse s e Bidirectional Material Temperature 19 4 C Repeatability Humidity 36 Forward Reverse l Bidirectional Pressure 980 hPa Backlash Mean Max 10 T 16 0 0 E 2 m 2 E 6 E 42 m 46 an 9 s se s Sign Reverse Mear Bidirectional Mean 3 Sigma X Reverse Data Points Operator 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 Interval Beam Strength Tes Minute Second 0 S No Time Value 1 193114 0 001894 En
30. hee ee Pee o eue eet hebes eed 4 2 GETTING BASIC INFORMATION FROM THE SYSTEM sees nennen enne en nenne seen 4 3 ADJUSTMENT OF THE OPTICAL PATH scssescsscssccscssssssssnncesscscnenssseaceesesscsenssssseeessecscsenseses 4 6 BASIC RULES OF AN OPTICAL PATH ADJUST MENT eese nennen 4 7 ADIUSTMENTD PROCESS icti eO eec pais sett cete o deed oe an eae eau Melo 4 8 MEASUREMENT SEIT 2 2 ent in 5 1 LINEAR DISPLACEMENT MEASUREMENT cocococononononononononononononononononononononononononononononononononononos 5 3 LINEAR DISPLACEMENT VELOCITY MEASUREMENT eee nnn innen 5 4 Velocm raph ec c tes cede ciel tco E AR RE A RANA 5 4 LINEAR POSITIONING MEASUREMENT e 5 6 RECORDINGMODE IEA A ae ales ace sae AL A AAA 5 12 ANGULAR MEAS UREM ENT ceeeitizstes ete eko diana reno ro nc csi 6 1 MEASURINGSET FOR ANGULAR MEASUREMERNTS 6 1 MEASUREMENT OF ANGLE DEVIATIONG cccccccccssessesscecececeseeseeeseecececeseaseessesceseeeseasensseeees 6 3 STRAIGH UNESS MEASUREMENTS iS NRI e baee rst Evi cana eR IDAI quu 6 4 FLATNESS MEAS UREMIEEN TS isesie teta se essere eonenn nenen onnenn 7 1 PREPARATIONS 0 AAA red e re eye a RI e E eo o ve dad 7 1 ADJUST MENT OF OPTICS FOR THE FLATNESS MEASUREMENTS ccssccscesceseessesssseceseceesenenens 7 2 Optical path adjustment in the axis e a vector eto rr lu vete OH Ed yes 7 4 Optical path adjustment in the axes 3 6 MC Co o RC C OO Ro ta 7 4 Optical path adjustment in
31. hing on drawing on the graph of measuring points from all cycles active cycle is drown 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 which 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 5 8 LINEAR MEASUREMENTS 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 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 option 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
32. ient 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 A 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 i 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 Lj 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 than the wavelength changes on the whole path length Li L 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 2 7 PRINCIPLES OF OPERA TION only this length The correction will not be made on a dead path L In this way the laser system will move the base point A dead path error is the more severe the greater is the distance between the interferometer and the base point This erro
33. ies on the frequency diagram after changing from Distance to Velocity and to Acceleration fig 8 5 It happens so accordingly to the theory from which results Ean fn Evn Epa fn Ean Where Ep amplitude of n th frequency when Distance is chosen Ey amplitude of n th frequency when Velocity is chosen Ea amplitude of n th frequency when Acceleration is chosen f n th frequency 7 5 VIBRATION MEASUREMENTS FIG 8 5 DIFFERENT FREQUENCIES AMPLITUDES IN DEPENDANCE ON TECHNICAL DATA 10 TECHNICAL DATA System specifications 1 Straightness measurement 0 12m 0 02 um for 100 mm 0 with angular optics base 0 12m 0 Blatness 0 02 um for 100 mm t 0 5 96 Vertical ran ge 2 mm base Straightness measurement TE VERAS 1 0 5 0 15L ot SUV with wollastone prism um Straightness measurement 3D 0 10m 0 1 um 3 2 x L um L in meter L axis length in meters for resolution 1 nm 7 1 TECHNICAL DATA Laser head Zeeman HeNe laser with frequency Laser type stabilization Wavelength vacuum 632 991354 nm Wavelen gth accuracy 0 02 ppm Short time stability 0 002 ppm 1 hour B MIS Beam diameter Distance between out and ingoin g beam Laser head dimensions 60x60x245 mm Net NE po Lg g Class 2 Laser OE A accordingto PN Safety class 91 T 06700 System work conditions Humidity range 10 90 Power supply 35 W during heating Po
34. iners etc 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 1 1 INTRODUCTION instrument and the manual should be inspected and reviewed for safety markings and instructions before operation Warnings Although the laser measurement system LP30 3D was design to be used in harsh environments the following conditions must be met The laser head must not be put near strong magnetic fields 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 The head must not be thrown or dropped Keep the optical components clean and avoid scratching them When the optics is dusted clean it with pure alcohol Do not use the system beyond its work conditions PRINCIPLES OF OPERA TION 2 PRINCIPLES OF OPERATION The rules of laser displacement measurements Displacement measurements with the use of a laser interferometer allow obtaining the accuracy of an displacement measurements 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 goes to the ref
35. ition 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 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 7 10 STRA IGHTNESS MEASUREMENTS 3D 8 STRAIGHTNESS MEASUREMENTS 3D Straightness squareness measurement highlight any bending component or overall misalignment in the guideways of a machine This could be a result of a wear in guideways an accident or poor machine foundations The straightness squareness errors will have a direct effect on a machine geometry and as the result on machining accuracy The quick assessment of the machine geometry is one of the most important action required when the machine is mounted on the foundation The geometry measurements are one of the most time consuming measurements the commonly used Wollastone prism optics is expensive and very difficult to adjust Operation of the system with the Wollastone prism optics require high skilled personnel There are three methods of straightness measurement with angular optics with Wollastone prism and with 3D method The method with the angular optics was presented in section ANGULAR MEAS UREMENT The optics with the Wollastone prism is supplied optionally The method 3D of straightness measurement don t require any
36. locity x Measurement Help Eile Edit I FO warna E eed 0 000 mm s L Measurement oms opt ams om Of om oms OM eps op 005 006 oms om 087 om ops Dm os 01 0105 oM ans Tw kd Average Velocity 0 001 mm s Main Menu 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 Wykres Predkosi 9 17717 Predkos nm s ey pumped may ey ete aay ey sdf sey me uma ma it a a i a 2 2 2 2 2 2 2 2 2 2 2 2 2 2 4 2 2 2 2 2 22 2 2 2 2 4 z Czas s FIG 5 5 EXAMPLE GRAPH OF CHANGES OF LINEAR DISPLACEMENT VELOCITY 5 5 LINEAR MEASUREMENTS Program also counts an average velocity from a visible range on the graph Possible is 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
37. ng adjustment screw set two crosses blue and green to the 4 10 OPERATION centre of the screen Blue cross corresponds to reference beam while the green one to measuring beam see Fig 4 9 e Laser Meosurement system DIS U HE G 0 00000 Beam Strength Digits El ULT Change m m Environmental Measurement Parameters Humidity 50 Distance Axis X Start position 0 000000 lt 7 Pressure 994 hPa Adjustment Sign 100 Material Air Temp 200 Y em 1i ym C Average temp 20 0 7 T Resolution 100 nm 100 c 100 80 60 40 20 O 20 40 60 680 100 Record Reset Position Reset Position Main Menu FIG 4 9 CORRECT ADJUSTM ENT OF OPTICAL PATH 12 Reset displayed position using Reset button on the display System is ready to work 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 9 LINEAR MEASUREMENTS 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
38. o 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 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 U E 2 y 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 than 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 Where n a refraction coefficient 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 2 5 PRINCIPLES OF OPERA TION The dependence 77 for the air was empirically determined by Edien and is described as 12 105 P 0 613 T 10 0613 0 00997 T 1228775 107 P TPH 1 0 003661 T 4 An 3033 10 H 00576277 5 From the above equations one may obtain the refraction coefficient dependences on T P and H in usual conditions T 293K P 1000hPa H 50 2n __9 93 10 L or K on 0 27 107 oP hPa 2n __9 96 10 E oH It is worth to notice that
39. ocessor 90 MHz or better SVGA graphic card making possible working with resolution 800x600 Software installation 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 3 1 PREPARATIONS The Laser Interferometer system elements The number of elements the system consists depends on desired types of measurements To the standard set for linear measurements belong l Z X o on c gt 11 1 x Laser head Laser Interferometer 1 x Power supply Laser Interferometer Power Supply 1 x Tripod stand 1 x Environmental Compensation Unit ECU SMI 1 x Laser head to power supply cable 2 x Magnetic holder UMI 1 x Linear interferometer IL1 1 x Linear retro reflector RL1 3 x Basis temperature sensor T1 T2 T3 1 x RS232C cable 1 x Manual Strobe cable See fig 3 1 on the next page for pictures of the elements of the standard set Additional elements for angular measurements are 1 2 3 4 1 x Angular interferometer IK 1 x Angular retro reflector RK1 2 x Beam directing mirror ZK1 1 x Rotary table SO1 3 3 Fig 3 1 The elements of the standard set PREPARATIONS OPERATION 4 OPERATION Preparing the interferometer to work The Laser Interferometer LP30 3D is supplied from autonomous power supply Laser Interferometer Power Supply Communication with a PC computer is performed by the RS 232C or U
40. r is especially important in laser interferometers where the interferometer is build up in a common casing with a laser head because it is than very difficult to reduce a dead path Interferometer Base point Reflector Null point No Laser head E L2 Interferometer Base point Null point l Reflector AS qJ Laser head Fa The correct deployment of the optical components for reducing a dead path error FIG 2 4 AN ILLUSTRATION OF A DEAD PATH ERROR A 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 than a difference between the real distance and the measured distance occurs This error of unadjustment is known as a 2 8 PRINCIPLES OF OPERA TION 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 than the beam must be perpendicular to it If the machine changes its position form point A to point B than the beam stays perpendicular to the mirror but moves on its surface The distance measured by the laser interferometer Li ys will be smaller than the real distance Ly according to Lims Lu cosO 6 The above equation is valid also when as a reflector a corn cube is used Laser beam Reflectors Laser head Machine s movenr nt axis FIG 2 5 THE BEAM UNADJUSTMENT AS A CAUSE OF A C
41. rred to normal conditions temperature 20 C pressure 1016 hPa humidity 50 9 4 5 OPERATION Adjustment of the optical path An adjustment of the optical set up should be conducted in option Display It can 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 OPERATION a b C FIG 4 5 DIAPHRAGM POSITIONS A RIGHT B CENTRAL C LEFT During transportation or when system is not used corre
42. rt For that reason the retro reflector must not be in theses measurements used with the magnetic holder UMI It must be also remembered that the system measures the vibration 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 VIBRATION MEASUREMENTS Inte rfe ro meter IL 1 Retroreflector A CN o A NR 2 lug ep p Interferometer B IL 1 mv ce I Vibrations Vibrations not important important Retro reflector RL1 a FIG 8 1 VIBRATION MEASUREMENT IN DIFFERENT AXES FIG 8 2 EXAMPLE OF PROPERLY ATTACHED RETRO REFLECTOR 7 2 VIBRATION MEASUREMENTS 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 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 Laser Measurement Sistas E
43. ss chosen from Menu Main fig 6 6 bh Laser Measuremen L System Straightness xj Eile Edit Measurement Help l EE AE 0 Move Retroreflektor jos to point 4 or STOP n n 1 Detance ee p Czas oczekiwania 3 5 s Stop IU Main Menu reis Method Bare Largh 100 e Era Pri Fa Matted FIG 6 6 STREIGHTNESS MEASUREMENT WINDOW The measurement can be done in an automatic mode standard arrangement or in a manual mode with manual capturing of measuring points In the automatic mode capturing of the measuring points takes place when a temporary time interval runs out The time between capturing the measuring 6 5 ANGULAR MEASUREMENTS points is used to 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 to 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 If
44. ss 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 source of noise that lower accuracy of the measurement When required accuracy of straightness measurement for 7 3 STRA IGHTNESS MEASUREMENTS 3D tested machine is not satisfactory one have to proceed to measurements with the use of angular optics or with the Wollastone prism 7 4 VIBRATION MEASUREMENTS 9 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 UMI 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 To obtain correct results a point of attaching the retro reflector to the corpse of a measured machine must be carefully chosen If the point is chosen improperly than instead of a sought frequency f a multiple frequencies n f appear where n 1 2 on the FFT cha
45. stem is 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 ri z ement System Linear Positioning BFK130X di2 Ele Ect Meacuement yew Heb Linear Positioning Error Plot Results lorm INMTBA hd Error um Foward Mean Forward Mesn 3Sigma r Reverse Mean Bidrectonsl Mean Bidrectonsl Mean 3Sigma Reverse Data Ponts Bacias Reverse Mean 3 Signs Forward Data Poris Axis Scale Parameters Previous Menu Audomafy pont capture Atom pont generador Cycle mamber 2 Lintowe Stop After Cycle 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 Under the graph buttons used for the change of the axis scale Axis Scale automatic scaling or assignment minimum and maximum values choosing of 5 10 LINEAR MEASUREMENTS parameters shown on t
46. the axes 5 and Do 7 6 OPTICAL PATH ADJUSTMENT IN THE AXES 2 AND 4 Leere cesse eee eere eene enne 7 8 S TRAIGHTN ESS MEASUREMENTS 3D eese esee esee senenn onnenn 7 1 VIBRATION MEAS UREMEN T5 tiiitis soi orti Yee Pb eese vo keen nA MP nonne 7 1 MEASUREMENTS A aii 7 3 TECHNICAL DATA is 7 1 SYSTEM SPBCIEIGATTONS dete ire eod i n A 7 1 LASER HEAD ica A A d a A dede eere 7 2 SYSTEM WORK CONDITIONS c eee eue cette eh coe Sl Sal tee e eot e cp tal a 7 2 POWERS URPLY 5 2 nut oen nM 7 2 PC INDEREAGCE2 sutil lid 7 2 ENVIRONMENT COMPENS AT TON 421b bsec n PEEL MAREA ta 7 3 INTRODUCTION 1 INTRODUCTION Laser measurement system LP30 3D is a two frequency interferometer intended to be used mainly in machine geometry measurements Its small size and low weight simplify transportation and make the instrument especially useful for service applications Software version for Windows 9x NT 2k XP and automation of many measurement processes make the interferometer easy to use Software compliant with ISO DIS 230 and PN 93 M55580 enable making rapports and diagrams It is possible to choose statistical results processing according to norms ISO 230 2 European VDI DGQ 3441 German NMTBA US A BSI BS 4656 Part 16 British and PN 93 M55580 Polish Very good technical parameters of the interferometer allow using it also in scientific laboratories for precision positioning for scaling optical and magnetic l
47. the options connected with the process of measurement Start beginning of measurements Stop break of 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 5 7 LINEAR MEASUREMENTS Capture or by pressing pulse switcher of Strobe If this option is not active points 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 Option View serves to switching on or off a panel Target Position Error Table and to switc
48. to the standing retro reflector 5 3 LINEAR MEASUREMENTS 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 executed in option Display The type 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 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 1 e Save Save as Print LINEAR MEASUREMENTS bh Laser Measurement System Ve
49. ue of the angle deviation in relation to the first point is shown It is also possible to measure change of the angle deviation in the same point if the inclination of retro reflector changes Straightness measurements The straightness measurements are driven along a straight line to which side surface of the angular retro reflector base is tangent In order to get the correct measurement the straight ruler along which retro reflector base will be pushed should be fasten on a measured axis In every moment of the measurement side surface of the retro reflector base should be tangent to the ruler see fig 6 5 FIG 6 5 AN EXAMPLE OF OPTICAL COMPONENTS SETUP IN STRAIGHT NESS MEASUREMENT 6 4 ANGULAR MEASUREMENTS Required measuring set a PC computer a laser head with a laser interferometer power supply a stand Tripod two magnetic holders UMI or UM2 a Environmental Compensation Unit ECU SMI sensors of basis temperature TI T2 T3 an angular interferometer IK1 an angular retro reflector RK1 on a support base P100 mm a remote control Strobe The Straightness measurement is based on pushing angular retro reflector about an interval 100 mm and measuring its angle deviation Before accession to the measurement measuring points should be marked every 100 mm distance on the leading ruler or on the examined surface It is recommended using ruler with scale The straightness measurement is performed in the option Straightne
50. vironmental 2 183125 0001936 3 19 31 35 0 002012 meters v Humidity 4 4 193145 0002008 t position 0 000000 lt 5 193155 0 002208 B 193205 0 002246 E j 2 wi v Pressure 989 7 ferial v Air Temp 22 1 l lt um C Save to file End Recording Help 7 Average temp 21 7 Resolution 10 nm dx 2 T3 2177206208199 ZU 100 100 60 60 40 20 0 20 40 60 680 100 Record Reset Position Main Menu FIG 5 9 RECORDING DATA MODE Pressing End Recording finishes the data recording The results can be saved with the choice of Save to file In fig 5 9 the example of Data Record is presented 5 12 ANGULAR MEA SUREMENTS 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 s FIG 6 1 SETUP FOR ANGULAR M EASUREM ENTS IN X AXIS 6 1 ANGULAR MEASUREMENTS Change of measuring axis will demand displacements of angular optics figures 6 1 6 2 and 6 3 FIG 6 3 SETUP FOR ANGULAR MEASUREMENTS IN Z AXIS Required measuring set a computer a laser head with an interferometer power supply a stand Tripod two magnetic holders UMI or UM2 a 6 2 ANGULAR MEASUREMENTS Environmental Compensation Unit ECU SMI sensors of
51. wer 10 W work PC interface Type RS 232C USB 7 2 TECHNICAL DATA Environment compensation Wavelength compensation Manual Environments parameters entered from key board Automatic With the use of the Environmental Compensation Unit ECU Parameters of the Environmental Compensation Unit ECU compensation Range 10 90 accuracy 10 Temperature 3 s pressure 2s humidity 30 s Dimension 050x55 mm Material temperature compensation Manual Temperature of material entered from key board With the use of 1 to 3 temperature sensors O p 8 Our products are subject to continuous further development and improvement Subject to technical changes without prior notice 7 3
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