Home

Optino manual

1. Opt wes sH Anatysis Piot T 1000 Live C Auto Lens 1GAiig se Coll FF C MCai Follow the alignment indications given by the circles and arrows superposed on the Shack Hartmann image that is displayed on the screen as well as the values given at the top of the image to adjust the optical system for getting the alignment When the centers of the two circles are inside the defined tolerances a white circle and a beep will give you the indication that the correct alignment has been achieved and you can uncheck the Align button on the dialog bar BLU dx 15microns dy 6microns 12 The image displayed on your screen is also saved in the directory for results specified in the SH Directories page with the name Align0001 fit The image is continuously overwritten the saved image contains always the last image on the screen If for any reason Sensoft is not able to analyze the image the program will go in Pause mode and a dialog will appear on the bottom right corner of the screen You can restart the analysis by pressing the button on this dialog 1 2 8 Collimate the light from the optical system being tested Once the alignment is done move the Test element to ensure that collimated light is falling on the lenslet array To do this check the Coll box in the dialog bar this will start the Live image and computations will be done to c
2. e ep ess oes es es Ji pa s el ese ess pes ses pes s E E e s pes ig ee c prs e e les sl T ond 1 1 1 7 LET EE 80 HAH FI SET 4 KAF 3200E a aF Bee el so eR rama amam sp CS RE estre em e epe re e n em en re mens ente een 88 227 SA e Ed ES Eu Fr 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 Wavelength nm 181 14 4 Cooled camera 3 350 1100nm 30x30 spots 14 4 1 Cooled digital camera with CCD sensor The Peltier cooled CCD camera from SBIG model 9XE is offered as an optional camera Since the camera is cooled long integration times can be used This is especially useful when the flux of the light source is low for example when using a narrow band filter USB controlled Compared to camera number 2 the download time is fast 0 5sec 14 4 2 Characteristics Kodak Enhanced KAF 0261E Class 1 Texas Instruments TC 237 Pixel Array 512 x 512 pixels 10 2 mm x 10 2 mm Pixel Size 20 x 20u Full Well Capacity 150 000 e Dark Current 10e pixel sec at 0 C 14 4 3 Quantum efficiency O 7 0 6 0 5 q 0 4 p
3. The analysis will start and you will see graph shown below 89 Zemike coefficient nm 300 Real time Zemike coefficients On line display of abetrations You can choose to focus on SA3 and Defocus by using the Aberrations Menu By clicking on one aberration the correspondent line aberration will disappear from the plot above File Edit View Image arithmetic Motor Align Simulation Utilities Aberrations Window Help Aberrations menu Defocus Tit Coma Sa3 Ast3 Tricoma Qast The values of the default coefficient aberrations will be displayed on a toolbar that will appear on the screen only during the loop The values of the coefficient will appear on a red or green background depending if the value is outside or inside the tolerance defined in the Loop param dialog 90 If desired you can also look at the spot diagram and the wavefront contour plot In that case do not fit SA3 and defocus in SH Zernikes Shack Hartmann Directories Zemikes Analysis parameters Utilities Graphics Default Terms to fit and subtract from data RE 11 Tilt 13 Coma RE 22 astigmatism Select from the following ce Higher order Coma Higher order Astigma Higher order TriCome RE Higher order QuadAs igher order Foil 02 DMocus 0 4 spfferical 3rd w Extra terms to fit
4. DS 152 10 2 Preliminare S onire Divs e cabs Cos A Soca SM dde nue don a Rte bs did et 152 10 2 2 The titia steps ttes ee Eee Ua can ee th ete ne E deeper 152 10 2 3 Getting parallel light with Optino automatic ss 152 10 2 4 Getting parallel light with OMI manual ss 154 10 2 5 Getting diverging or converging light 155 10 2 6 Calibration of converging or diverging light ss 155 10 2 7 Properties of the collimating lens ss 156 10 3 PHOTOGRAPH ito Serena onini d t et ette 157 CHAPTER 11 SERIAL COMMUNICATION PROTOCOL FOR STEPPER MOTOR OF OPTINO PUNTINO BE AND ere eee Ro ed na oe eV areae o sene RENS Sere EE 158 11 1 DEFINITIONS AND SETTINGS 5225502 acie I Rite as e io Bre ente On Gt RS 159 11 2 OPERATIVE COMMANDS ete ie ae ete Gee dee ie centes e tu ertet ed eset 160 TT STINQUIRY COMMANDS eee e tea cte ote A ERR 161 CHAPTER 12 SENSOFT AND ZERNIKE POLYNOMIALS ee eee ee ee eee een eee ee setas etes ta osea 162 12 1 BRIEF EXPLANATION OF ZERNIKE POLYNOMIALS esse enne en tenen nnne inneren 163 12 2 THE DIFFERENT ZERNIKE POLYNOMIALS IN USE see enne enne ennt 165 12 3 ZERNIKE POLYNOMIALS USED IN SENSOFT 167 12 4 EXPRESSIONS FOR THE FIRST 8 TERMS FOR ANNU
5. a Contour plot of ellipticity Note the four read areas on the edges These are due to the stress caused the screws holding the fiber 5 4 Alignment using coma and astigmatism Once the reference image has been taken the optical system is setup correctly along with the illumination system as explained in the sections above After taking a Test image and checking that the optical parameters the normalized pupil should be 1 and the exposure time light intensity are OK do the following See that you have chosen to fit the first seven terms default in the SH Zernike section clicking on the LC button close to the Loop choose the Align Coma Ast plot option 86 Chapter 5 On line adjustment of optical systems Loop param Range of alert values for aberration coefficients The analysis will start and you will see a graph shown below 87 Real time Alignment Zemike coefficient nm Online alignment using coma and astigmatism You can choose to focus on the total coma and astigmatism and or the components by clicking on the Align toolbar that appears once the loop is started The align toolbar If desired you can also look at the spot diagram and the wavefront contour plot In that case do not fit coma and astigmatism in SH Zernikes Shack Hartmann Directories Zemikes Analysis parameters Utilities Graphics Term
6. essent enne 13 1 2 10 Ensure that you are using the correct optical setup and parameters in the Opt page 13 1 2 HI Specify the ellipticity Cutoff see a ir teet ea eter etre tei Y Pee tere 14 1 2 12 Doa Test analysis vit ara ete e b t a Uie e rp e E n ean ea Dee ERR uS 14 1 2 13 Do a full analysis by using the Lens button ss 17 1 2 14 Do an analysis in a continuous loop cessere eene nennen eene enne nenne nnne 20 1 2 15 Off line andlysis ode eae iet e e e ses qe eco eri tor d e Pee Ete ee 22 1 2 16 Check the Actual Quality Potential quality and Residual Quality 22 1 3 OPTINO GETTING PARALLEL LIGHT WITH THE MOTORIZED COLLIMATOR sus 23 1 4 THE OPENING SGREEN M 25 1 5 CHANGING AND ADJUSTING THE BEAM SPLITTER serrer 31 1 5 1 The beam splitters and the shift of image on the SH camera ss 31 1 3 2 Mounting the beam splitter zoe da ooh cous bees ANR net RED a 31 1 5 3 Adjustment of beam splitter in azimuth and altitude 3l 1 5 4 Adjustment of beam splitter for Optinos manufactured before 2002 33 1 6 THE INTERNAL ILLUMINATION 33 L617 Mounting the filler us t dee abra le eda datus 33 L A SUMMARY OF PROPERTIES E TOES 35 CHAPTER 2 OMI OPTINO MINISENSOR INITIAL SETUP AND 36 2 1 OMI GETTING STARTED HOW TO GET A GOOD SH IMAGE nr 37 2 220ME
7. 0 2 0 1 400 500 600 700 800 900 1000 Wavelength nm 182 14 5 Cooled camera 4 325 1100nm 50x50 spots 14 5 1 Large format cooled digital camera with CCD sensor The Peltier cooled CCD camera from SBIG ST1301AE is offered as an optional camera Since the camera is cooled long integration times can be used This is especially useful when the flux of the light source is low for example when using a narrow band filter USB controlled 14 5 2 Characteristics CCD KAF 1301E LE Array 1280 x 1024 pixels Pixel Size 16u square Peak QE 73 Image Area 20 5 mm x 16 4 mm 14 5 3 Quantum efficiency Absolute Quantum Efficiency 300 400 500 600 700 800 900 1000 1100 1200 Wavelength nm 183 14 6 Cooled camera 5 325 1100nm 70x70 spots 14 6 1 Large format cooled digital camera with CCD sensor The Peltier cooled CCD camera from SBIG ST1001E is offered as an optional camera Since the camera is cooled long integration times can be used This is especially useful when the flux of the light source is low for example when using a narrow band filter USB controlled 14 6 2 Characteristics CCD KAF 1001E Array 1024 x 1024 pixels Pixel Size 24u Peak QE 72 Image Area 24 6 mm x 24 6 mm 14 6 3 Quantum efficiency Quantum Efficiency ST 1001E KAF 1001E 400 450 500 550 600 650 700 750 800 850 90
8. Flux pixel Signal noise 100 500 400 300 200 100 X pixels hown image s for the reference istribution 99 ity bottom d iptic above Compare with the 3D and contour plots later in this chapter Plot of intensity top and ell Chapter 6 Analysis of results 1 the shapes and intensity of the spots 6 6 Examples of 3D and contour plots of distribution of centroids This graph gives the total intensity of each of the spots displayed in the centroid graph in a contour form An example is given in the figure below for a reference image When the distribution of intensity should is uniform on the image the value of the contour levels on the graphs are very close P V 1847 rms 367 counts 2022 1816 1611 1406 1201 995 790 585 380 P V 1847 rms 367 counts 2022 1816 1611 1406 1201 995 790 585 380 Intensity distribution 3D bottom and contours top over the reference image The variation in intensity is small The edges are affected by the presence of weak spots due to 100 Chapter 6 Analysis of results 1 the shapes and intensity of the spots diffraction effects In the analysis of the image of the optical system under test the software automatically compensates for this variation P V 0 473 rms 0 063 Ellipticity 0 474 0 421 0 368 0 316 0 263 0 210 0 158 0 105 0 053 P 0 473 rms 0 063 Ellipticity 0 474 0 421 0 368 0 316 0 263
9. Setup In the above configuration light is made parallel by the collimating lens C1 and passes through the beam splitter It comes to a focus at F after passing through the collimator C2 This is also the focus of the lens L under test It falls on a flat mirror M which should be of a high quality say 4 10 or 2 20 depending on the accuracy required for testing the lens L The mirror should have a minimum diameter equal to that of the lens L and the focal ratio of the lens C2 should match that of the lens L Instrument Optino The collimator C2 can be changed easily to match the focal ratio of the lens L Calibration The aberrations of the SH system itself are removed taking a calibration image of a small high quality like for the flat mirror above spherical mirror instead of the lens L Input Values for wavefront analysis D npu input diameter of beam from Optino Ds diameter of test element fles focal length of test test element focal length of collimator C2 col Output information Along with the Zernike coefficients the wavefront and optical quality Sensoft gives diagnostics for correcting defocus and spherical aberration which is minimized by shifting the focal plane These corrections can be based on analytical formulae or on a lookup table provided by the user 119 Single or double pass Double pass 120 Chapter 8 Optino Puntino test configurations 8 11 Test of multiple
10. 8 Default 91 Chapter 6 Analysis of results 1 the shapes and intensity of the spots 92 6 1 Introduction All the computations done by Sensoft computation of surface computation of Zernike coefficients etc are based on the computations of the centroids of the spots However the shape of the centroids themselves can be used to obtain information on the surface of the optical system from which they are reflected An irregular shape will give rise to an elongated spot while a regular shape will give a spot that is almost circular see Section 1 2 11 for the mathematical definition of ellipticity Round spots have ellipticity amp 0 and elongated ones amp 1 A surface that has less reflectivity will give spots with lower intensity An elliptical spot left and a regular spot right The intensity of the elliptical spot is lower indicating that the area of diameter 300u that of one lenslet array from which it was reflected had a lower reflectivity compared to that on the right Of course not only can individual spots be studied but the distribution over the whole surface can also be studied While this chapter explains the use of the centroids for understanding the surface quality of the optical system it is to be noted that these parameters have also a role to play in the analysis of the images For example in general for a good SH analysis all spots with ellipticity 20 7 are rejected Thus if you
11. Residual Quality Abbreviated as RQ This is obtained after subtracting the effect of the user selected Zernike terms from the data The wavefront as well as other parameters Encircled Energy Strehl Ratio are also given Thus the user can have a full analysis of the optical system in a single step 22 1 3 Optino getting parallel light with the motorized collimator This feature is available only in the OptinoPro and OptinoEE versions In Optino Uno the collimator is preset before shipment though it can be moved if required The COM port to which the stepper motor is connected is automatically detected when you launch Sensoft Mounta plane mirror at the output flange of Optino and center the SH image on the camera Optimize the exposure time for the SH image as described in Section 1 2 2 Check the MCol box in the dialog bar Sensoft will display the dialog shown in the picture below Motorized collimation Motorized Collimator of Qoia Last position found steps 1187 Select parameters for new collimation New collimation gt Tolerance 0 1 10 02 Move to position gt solute position Absolute step no 1000 1000 Specify the tolerances for the motorized collimator a value of 0 2 is recommended Press OK and the SH image is acquired in continuous mode and displayed on the PC screen software for Optino 3 Sensoft Shack Hartmann wave
12. P V waves Defocus nm 187 Removed PST TLT PHR foer ture Sdie The 3D surface plot after removal of Tilt Piston and Power defocus obtained with the Zygo interferometer The P V is 0 1473 waves 0858 0681 0504 0326 0149 0 0028 0 0206 0 0383 0 0560 0 0737 ooooo P V 0 1596 rms 0 0279 waves The 3D surface plot obtained with Optino after removal of tilt and defocus There is a good correspondence with the figure at left The P V is 0 1596 waves Conclusions Optino based on the Shack Hartmann principle gives results that are in excellent agreement with those obtained from the Zygo interferometer 188 Chapter 16 Dimensions of Optino 189 16 1 Dimensions of Optino front flange All dimensions are in mm In some versions of Optino the front flange has the top two holes for the mounting pins The height of the optical axis is 65 5mm from the base 190 16 2 Optino the various components Firewire camera It can be substituted with a cooled camera for Fiber from fiber optic light source or laser or other light source e higher sampling e higher accuracy Filter holder e low light levels Two screws for 2 filter holder ing holes for external ent like beam expanders Two screws for camera mounting M35x1 Wa hole for collimators Two screws that can be removed adjusting the beam splitter in azimut 191 16 3 Dimensions of O
13. Align the two images using the Align command Bring the Test element to the focus using the Coll command Automatically adjust the exposure time and take a Test image Do the Analysis How the test and reference image is taken depends on the optical setup and is explained in the following pages Also see Chapter Optino Test configurations 46 4 2 Terminology Table 3 SH image of the reference calibration image Test SH image of the test optical element Sometimes also called Lens SH All terms in square brackets refer to the Sensoft buttons or property sheets 47 Chapter 4 Testing with Optino reference guide 4 3 The optical test configurations 4 3 1 Converging lens in external illumination single pass The Test optical element is illuminated by an external aberration free light source The test is done in single pass as the light passes through the optical element once 4 3 1 1 Light source for illuminating the test element Spot optics can supply aberration free light sources maximum aberration 8 of up to 400mm in diameter 4 3 1 2 Calibration of Optino A reference source P50 is used for calibrating the aberrations of Optino as shown below Calibration source P50 48 Chapter 4 Testing with Optino reference guide 4 3 1 3 Maximum diameter that can be tested The maximum diameter that can be tested depends only on the diameter of the aberration free calibration light source
14. In this dialog you can select the parameters for the loop setup The tolerances for coefficients for the most common aberrations the default value used by Sensoft is 50nm If the aberration coefficient measured in the loop is greater than this tolerance Sensoft will change the background of the aberration fields in the Coefficient toolbar that will appear during the loop 20 e Choose what you desire to see in graphical form e Show Hide the Shack Hartmann image display together with the graphs during the acquisition By selecting the Image stretching factor you can see a larger 2x2 or smaller 3x3 image e Save the values of the coefficients in a log file by checking the box save coefficients in log file In this case a file will be created in the output results directory under the subdirectory Loop If you stop and restart the loop Sensoft will ask if you want to overwrite the previous log file if your answer is No a new log file will be created in the new directory Loop and so on Check the Loop box in the dialog bar to start the loop The selected graph will be continuously refreshed on the screen A toolbar with the value of the coefficients is displayed during the loop the coefficients specified in the loop param dialog are shown with a green background if the value is inside the tolerances in ted if it is not Standard Zernikes x If you asked to display the Shack Hartmann image the image displayed o
15. Optino Pro and EE versions only Perform the on line analysis of the optical system SH image in a continuous loop Requires a previous acquisition and analysis of the reference image After the SH image is obtained the selected Zernike terms are fit to the data and the graph selected in the Par folder is plotted A coefficients toolbar displays the value of the first 10 default coefficients A red or green background for the fields indicates that the value of the coefficients obtained from the analysis is outside the tolerance given in the dialog that is opened by pressing on the EC button close to the Loop box in the dialog bar In the OptinoEE version during the loop the values of the first 7 coefficients can be saved in a log file on request and the coefficients can be sent to an external machine through serial communication During the loop Optino Pro and EE versions only the SH image acquired in continuous mode can be displayed if this is specified in the Par folder When the SH image is displayed the indications for alignment of lens vs reference image see next section are also given QAlign and Align Coll Used for on line alignment of the optical system SH image herein lens with respect to the reference image Requires that the reference image have been taken in advance The software gives the indication of the movement to be done in terms of up down left right to align the lens image When the alignment is inside the to
16. Please see Section on Test configurations 135 9 2 1 The models available BE150 Maximum beam size 140mm BE60 Maximum beam size 58 5mm BE25 Maximum beam size 23mm BEIR For infra red up to 1600nm Maximum beam diameter 23mm 136 9 2 2 Coupling the beam expander to Optino The figure below shows how the beam expander BE60 is coupled to Optino Optino right coupled to the beam expander BE60 at left To couple the two proceed as follows Screw in the coupling into the face plate of Optino Position the BE in front of Optino as shown above with the positioning pins lined up with the holes on the face plate of Optino Applying gentle pressure in the direction shown by the arrow above push the pins of the BE into the holes on the faceplate of Optino After ensuring that the pins are properly seated in the holes tighten the two setscrews shown by white circles above on the top and bottom of the BE The combination BE and Optino is ready for use now 137 9 3 Magnifications available 9 3 1 Different models available There are four different models of the beam expander available BE150 Maximum beam size 140mm BE60 Maximum beam size 58 5mm BE25 Maximum beam size 22mm BEIR For infra red up to 1600nm Maximum beam diameter 23mm 9 3 2 BE25 The lens positions and magnifications See section 9 6 on Changing the BE lenses Table 12 BE25 Maximum output diameter 23m
17. zoom histogram brightness and contrast rejection of bad spots The controls at the bottom of the bar display the name of the directory where the output results are saved selected in SH Directories the name of the last calibration reference and of the last image of the optics analyzed the normalized radius from the last analyzed image Finally the buttons to Show Hide the Info toolbar the Beam expander info toolbar only if the instrument includes the beam expander unit and the Motor toolbar OptinoPro and OptinoEE that are showed on the display when the program is launched The controls placed on the top of the bar allow the selection of parameters required for the analysis as explained below Select the optical test setup Enter the optical parameters for the optical system under test Enter the description for the test The values can be saved and loaded from a default file that can be selected using the Load Save optical configuration function in the File menu WES Specify the camera setup for uncooled camera binning and flip parameters gain regulation for cooled camera binning and temperature regulation parameters and the number of images to average both for reference and optical system SH image The average of images will reduce noise i e due to air effects The Check exposure time option is used for the automatic optimization of the exposure time Define the orientation of the Optino with respect
18. 0 210 0 158 0 105 0 053 Ellipticity 3D distribution bottom and contour plot over the reference image Except for the edges where the ellipticity is high due to diffraction effects see contour map of the intensity distribution above there is a very small variation in ellipticity 101 Chapter 7 Using Excel with Sensoft 102 7 1 Using Excel with Sensoft comparison of the Zernike coefficients and other results When you acquire and analyze a Lens image by clicking the Lens button in the dialog bar of Sensoft at the end of the Shack Hartmann analysis an Excel file is created updated whose name is taken from the prefix selected for the Lens image The Excel file is created in the directory for results outdir_results field selected in the SH folder For example if the prefix PN has been selected in the SH folder the file PN xls will be created during the analysis You can open the Excel file by launching Excel and selecting it from in the outdir_results directory Results from analysis of images with the same prefix but different counters like Mir001 Mir002 etc are presented in different columns The first three rows give details of the images analyzed The columns give the names and the values of The coefficients of the 7 default Zernike terms The diameter of the pot diagram containing the Encircled Energy The peak to valley P V of the surface reconstructed from the residu
19. 1 5 2 Mounting the beam splitter You will need to dismount the side front cover of Optino to change the beam splitter First remove the top cover and then unscrew the M4 hexagon setscrews using the metric Allen keys Unscrew the three hexagon setscrews at the back of the beam splitter Slide out the beam splitter and mount the new one 1 5 3 Adjustment of beam splitter in azimuth and altitude To adjust the beam splitter in azimuth or altitude unscrew one of the hexagon setscrews and tighten the other one see figure below You will require Allen keys 31 For adjusting the beam splitter in altitude For adjusting the beam splitter in azimuth For adjusting beam splitter in altitude For adjusting beam splitter in azimuth The two types of beam splitters used in Optino cube top and plate bottom They are used for alignment and centering of the collimated beam coming out of Optino In both cases the beam splitter can be changed for special applications e g different wavelengths 32 1 5 4 Adjustment of beam splitter for Optinos manufactured before 2002 For Optinos manufactured before 2002 it is not possible to change the beam splitter However the adjustment can be made as for the beam splitter shown below Explanation Beam splitter max thickness 5mm size 35x35mm Plastic pad or tape between beam splitter and set screws Hexagon setscrews for holding beam splitter Hexagon setscrews for adju
20. ALIGNMENT OB THE SPOTS ertet o rn neos e XE EA e ERE RE ce cnrs tou RR no e Eden uan 38 CHAPTER 3 SENSOFT OPTINO SOFTWARE INSTALLATION eee ee eee enne tenen tune tn sunu 39 3 1 SYSTEM REQUIREMENTS csssessscecececsesssececececeesescaececececsenseaeceeccecsessaaececececsessaaeeecececeensaaeaeeececeeneaaees 40 3 LZ System requirements for PC es tbe e tee eet tute Sais 40 3 1 3 Additional requirements for laptops esee 40 3 2 CAMERA SETTINGS NOI e Omne reb ne oboe ORDRE 41 3 2 1 Camera for getting Shack Hartmann images 41 3 2 LT Uncooled Catera ede Et ER RURSUS ER ERI RU ES 41 3 2 1 2 Cooled amet ss en eR Pe EIER RIS PX Andes ere ne tonne ele Te 41 3 3 INSTALLATION ee tn be rr E FO Qe ire RN an en dere 42 ii 3 3 1 Installing Sensoft Optino 2 aU E cas E EU Re e e RU Rd eges 3 3 2 Installing the hardware key eee nennen ennt ener teen 3 3 2 2 Windows 2000 XP 0 eeceeesessesseeseeeceeeeeeessesseeseeaeeeeeeee 3 3 3 Installing the SBIG SH CCD under Windows 2000 XP 3 3 4 Installing the Firewire uncooled camera for the first time 3 3 4 1 Installing the Firewire PCI card on your PC sise 3 3 4 2 Installing the camera under Windows 2000 XP ins 34 MISCELLANEOUS sciences esee eee ree e Ree ree 3 4 1 Upgrading the camera driver 3 4 1 1 Windows 2000 XP only esee 3 4 2 Us
21. BE6004 if you wish to have an output beam size of 49 mm Refer to Tables 12 13 and 14 The magnification factor is 8 2 L1 Mount a lens of focal length f11 40mm in the motorized carriage L2 Mount a lens of focal length f11 354 9mm mounted in position 9 see Table 13 and figure in section 9 3 Select the optical setup parameters and Beam expander parameters in the Opt folder Take the stepper motor to Home position and move it by 850 steps This will give the approximately correct separation of 396mm Make the light from the BE parallel as explained in Section 9 8 Store the value of the stepper motor position by checking the MBexp box You can go to this position without having to redo the collimation the next time you choose this combination and position 147 9 8 Steps for adjusting and getting the reference SH image from the beam expander Note Square brackets refer to commands of Sensoft 9 8 1 Calibration of the beam expander This will give the reference Optino SH image to calibrate out the aberrations of the BE See sections 9 3 to 9 7 above Mount if required filter in the illumination unit of Optino Use the internal illumination of Optino to get parallel light from Optino without the beam expander as explained in the Chapter 1 Optino Pro and EE Initial setup and use Section 1 3 Optino getting parallel light with the motorized collimator Dismount the fixed lens L1 and the movable lens L2 of the beam e
22. NP25 cen NP25 cof NP25 cmb NP25 prf NP25 res etc 18 Au the files are in binary format except for NP25 cof and NP25 sha which contain the results of the SH analysis You can review the output result file also off line by opening the Mir file with cof extension from the File menu See section 4 8 for details on off line analysis pressing the Lens button again the procedure restarts Sensoft will display a dialog asking if you want to overwrite the previously taken image or create a new one Image name definition Overwrite last image Create new image Lens0001 Create with new name Optimize exposure time Selecting Overwrite last image the image and all the output file will be overwritten Selecting Create a new image a new image will be created keeping the same Lens prefix specified in SH Directories and increasing the image counter if Mir0001 was the last saved image Mir0002 will be created and analyzed Selecting Create with new name a name of your choice can be specified in the field Enter new name checking Optimize exposure time the quick exposure time optimization QAuto will be done before the acquisition of the final image In all these cases by pressing OK you confirm your choice By pressing Cancel the program will not proceed The analysis uses the automatic threshold if you want to use the threshold value specified in the SH Analysis p
23. This value is also displayed in the Motor toolbar For the standard collimator EFL 75mm the position of the focus is about 1225 steps This is temperature and wavelength dependent Moving towards zero Home position of stepper motor gives diverging light and towards increasing steps maximum of 1750 steps gives diverging light Each step corresponds to 21 24 1 4 The opening screen When you run Sensoft for the first time the following screen appears Sensoft Shack Hartmann wavefront sensor software for Optino File Edit Toolbars Image arithmetic CCD Grid Motor Simulation Utilities Window Help _ 5 014 Live Mlaauto C Auto Dark Rer rest Lens 07 Loop Qasin Calin cot EO Mco v T xn CAacceptance_optino_pro0504 Ref REF_flat0001 fit Last FocusM0001 fit INFO The controls placed in the middle row of the bar become active when graph is active save copy paste print grid legend Hue color Black amp White scale for residual plot contour levels for wavefront contour plots conversion of wavefront in unit of waves 2D section on the wavefront selection of peak to valley PV for wavefront display An image is displayed subframe fullframe selection on line display of contour or 3D of spots contained in the selected subframe
24. Triangular Coma 3 3 TComa3 5 7 9 11 13 Quadratic 4 4 QAst3 6 8 10 12 Astigmatism Higher order 5 3 1 1 Higher order Higher order Higher order Total number 167 12 4 Expressions for the first 8 terms for Annular Zernike polynomials Include normalization factor Orthogonal to each other in the wavefront space Include obscuration factor Table 21 Annular Zernike polynomials Tilt z COS P Po 1 ey Defocus dr FE fords n Coma Jg BU te yr 2 1 eA 0442 4 4 3rd order J5 6 1 gr 1 Spherical 3 22 1 2 aberration pO ee ee pheric ms aberration ree Astigmatism cos 2p 1 amp e Triangular r cos 39 Quadratic r cos 49 9 astigmatism 10 Ate qe ae yy 168 12 5 Expressions for the first 8 terms for standard Zernike polynomials Include normalization factor Orthogonal to each other in the wavefront space Do not include obscuration factor Table 22 Standard un polynomials Emo ETES 0000 yan 0 BO 3rd order Spherical aberration J5 6r 6r 1 5th order Spherical aberration A 20r 30r 12r 1 feito 169 12 6 Expressions for the first 8 terms for Fringe Zernike polynomials Do not include normalization factor Orthogonal to each other in the wavefront space Do not include obscuration factor Used in interferometry Table 23
25. Z16 J 12 107 12r 3r cos 17 217 172 V12 10r 127 3r sing Chapter 13 References 173 13 1 References There are a number of excellent references in the literature The following table lists some books that will be useful It clearly is not a complete list Table 26 Author Publisher Born amp Wolf Principles of Pergamon Optics Press Comment Standard reference Hecht Optics Addison Wesley Mahajan Aberration SPIE Optical theory made Engineering simple Press Malacara Optical Shop John Wiley testing Astronomical John Wiley Optics Smith Warren Modern McGraw Hill Optical Engineering Welford Aberrations of Adam Hilger Optical Systems 174 For Annular Zernike polynomials See also the references to the original The standatd book for optical testing Good reference for astronomical optics Excellent explanation of many optical concepts Chapter 14 Cameras available with Optino and Puntino 175 14 1 Summary of Different cameras available with Optino and Puntino unique feature of the wavefront sensors made by Spot optics is the possibility of changing the camera according to the requirement of the test being done All the cameras can be mounted or dismounted from outside Optino Puntino The following is a summary of the camera properties and the suggested applications In all six cameras are available All of them can be run from the laptop The details for each
26. and the motor will move automatically to the correct position If you are using OMI then use the values of the collimator given in Section 10 2 7 below in a ray tracing program like Zemax Compute the position of the lens that gives you the desired defocus Move the motor to that position using the Hypertem In both the cases automatic manual if strongly converging or diverging light is used two problems can arise Problems with the combination of Test and reference images Spherical aberration of the diverging or converging beam This needs to be taken into account using ray tracing 155 10 2 7 Properties of the collimating lens Value 25mm 75mm 693mm 525mm Central thickness CT2 3 0mm Edge thickness ET 6 39mm 448mm 38 89 1304 87mm BaF 13 SFA CT1 CT2 10 3 Photograph of ECM Ex as The picture above Shows the M25 A fiber is deed to illuminate the pinhole unit at left The parallel light emerges from the right The power 12 500mA power connector and the serial port for the stepper motor control are also seen 157 Chapter 11 Serial communication protocol for stepper motor of Optino Puntino BE and ECM 158 11 1 Definitions and settings The stepper motor communication is through a serial port whose settings are as follows Baud rate 9600 Data bits 8 Stop bits 1 Parity None Flow control Xon Xoff The communication consists of ASCII stri
27. at F C2 is the collimator of the SH system It is not necessary to use parallel light for the test The measured aberrations will then no longer refer to those for parallel light but to one particular optical configuration that is used for the test Instrument Optino The collimator C2 can be changed to match the focal ratio of the lens L Calibration The aberrations of the SH system itself are removed by taking a calibration image with a calibration source placed at the focus of C2 Input Values for wavefront analysis D ey aperture of test element fley focal length of test element fl focal length of collimator Output information Along with the Zernike coefficients the wavefront and optical quality Sensoft gives diagnostics for correcting defocus and spherical aberration which is minimized by shifting the focal plane These corrections can be based on analytical formulae or on a lookup table provided by the user Single or double pass Single pass 111 8 5 Test of multi component lens in parallel light using external illumination Parallel light Setup In this configuration aberration free parallel light falls on the two lens system L and comes to a focus at F C2 is the collimator of the SH system Evidently any number of elements that form a converging system can be tested together It is not necessary to use parallel light for the test The measured aberrations will then no longer refer to those for
28. be used instead of the PCI card to control the camera from a laptop 3 2 1 2 Cooled camera On request the SBIG high speed USB cameras can be supported with Optino Refer to the installation manual provided by the manufacturer for the installation procedure of the SH CCD camera of your choice A total cable length of about 50m can be used 41 3 3 Installation 3 3 1 Installing Sensoft Optino The Sensoft Optino CD ROM must be inserted in the CD ROM drive install the Sensoft Optino and the drivers on a Windows 2000 or Windows XP system you must be logged in with Administrator privileges Click on the Setup icon contained in the CD ROM Follow the instructions on the screen Atthe end of the installation copy the contents of the Dark directory from the CDROM into the directory where you installed Sensoft 3 3 2 Installing the hardware key Sensoft can be used only with a dongle hardware key that must be connected to an USB port of your PC before the installation of the software To install the USB device driver for the dongle correctly follow the steps below Install the Sensoft Optino software from the installation CDROM Shutdown your PC Plug the dongle into a USB port 3 3 2 2 Windows 2000 XP To install the drivers on a Windows 2000 XP system you must be logged in with administrator privileges When you are prompted for the driver select the installation CDROM unit Run the SDLEXE contained in the Se
29. calibration reference image assumed for the analysis Red background means that the alignment is outside the tolerances defined in the Align dialog that is displayed by clicking on the button 30 close to the Align box in the dialog bar on the top of the screen green means that the alignment is inside the tolerances 1 5 Changing and adjusting the beam splitter 1 5 1 The beam splitters and the shift of image on the SH camera Optino comes with a cube beam splitter mounted as standard This can be changed if desired e g depending on the wavelength A plate beam splitter of size 35x35mm and maximum thickness 5mm can also be mounted The following table shows the shift of the center of the SH pattern on the chip corresponding to a refractive index of 1 50 and an angle of incidence of 45 For larger thicknesses the value is noticeable The standard beam splitter of Optino is made of float glass anti reflection coated and gives a shift of 0 32mm The camera in Optino is mounted with the long side of the chip along the displacement direction camera Firewire connectors pointing up Table 1 Thickness of beam splitter mm Deflection of SH pattern on camera mm 0 000 000 1 000 329 2 000 658 3 000 987 4 000 1 317 5 000 1 646 For large thickness beam splitters there is noticeable shift of the SH pattern on the SH camera This will require a new mounting for the C or T mount Please contact Spot optics for this
30. flat mirror 127 Single or double pass Double pass 128 8 15 Test of flat mirror in Ritchey Common setup Flat mirror under test ToS H system Radius of curvature of C2 spherical mirror Light source with pinhole Spherical mirror The Ritchey Common configuration is used for testing a flat mirror in conjunction with a spherical mirror First the SH image of the spherical mirror is obtained directly this becomes the calibration image Then the SH image of the flat spherical mirror is obtained using the configuration shown above Then the analysis proceeds in the usual way thus giving the optical quality of the flat mirror alone In the above configuration the spherical mirror has been placed at an angle of 90 degrees Other angles can be also used Instrument Optino The collimator C2 can be changed easily to match the focal ratio of the spherical mirror Calibration First the SH image of the spherical mirror is obtained directly this becomes the calibration image Clearly since the aberrations of the spherical mirror are removed by the calibration process it does not need to be of a very high quality Input Values for wavefront analysis input diameter of beam from Optino Des diameter of test element fles focal length of test test element fl focal length of collimator C2 col 129 Output information Sensoft gives the Zerni
31. image 96 distribution of S N over the image 97 distribution of the centroids 95 ellipticity 63 93 193 on line and off line display of the plots 95 plots 93 Coma 14 22 35 59 60 65 74 75 85 86 88 108 113 121 126 131 132 163 164 165 167 168 169 170 171 172 D Defocus 14 17 22 35 59 64 68 75 85 89 90 91 108 110 111 113 114 116 119 121 124 126 132 155 163 164 165 167 168 169 170 171 172 187 188 Diameter of image due to individual aberrations 76 E Ellipticity 3D and contour plots 100 Excel files 103 H Higher order aberrations 163 167 I Input parameters 2 9 13 15 16 25 26 30 37 58 64 66 73 74 147 Intensity 3D and contour plots 100 Interferometer 56 186 187 188 L Lapping plate analysis of results 92 the illumination system 33 M Mahajan V N 166 174 Malacara D J 174 N Noise of a camera 94 97 Normalized central hole 58 Normalized radius computation of 68 149 effect of sampling 71 no vignetting 68 with under filling of optical element 70 150 with vignetting 69 149 O Off line analysis 22 73 On line analysis 73 Optical quality Actual Quality AQ 17 22 103 Potential Quality PQ 22 103 Residual Quality RQ 22 103 Optino alignment of the SH camera 6 beam splitter shift of image on SH camera 31 beam splitter adjustment 31 beam split
32. not equal to 1 then one of the above three parameters is not correct or the optical system is very far from the correct focus or has a high spherical aberration Since aberrations like defocus and SA3 can change the size of the beam Sensoft computes the normalized beam based on geometrical parameters Furthermore Sensoft automatically compensates for the fact that a finite number of spots are used to represent the pupil Similar arguments apply for the other test configurations 68 4 10 3 The test beam is larger than the aperture of the optical element and is vignetted Dest lt D no BE test L D lt Dy with BE test Expanded beam Separation Fixed lens L2 69 Input beam D input 4 10 4 The beam from Optino or the BE does not fill the optical element completely Ds gt D no BE test L D gt Dg with BE test Separation D test Motorized lens Fixed lens L2 Sensoft takes this into account Also see section on the normalized radius 70 4 10 5 The effect of spot sampling on normalized radius The number of spots in the image also has a bearing on the computation of the normalized radius as the following table and graphs show Sensoft considers this automatically Table 8 No of spots Maximum in X or Y direction normalized radius 1 2 3 4 5 6 7 8 71 Chapter 4 Testing with Optino reference guide Maximum normalized radius as a f
33. of OMI to send light back to the lenslet array Use the Live button to start the exposure Adjust the exposure time and or the light intensity to get a good SH image The QAuto or Auto checkboxes can be checked to achieve this Adjust the tilt of the flat mirror to center the SH image on the camera The alignment of the SH camera is important the SH spots should be aligned along the rows and columns to a precision of about 1 pixel Alignment of the SH camera can be done by adjusting two screws at the top and left or bottom in some earlier models using Allen keys See section 2 2 37 2 2 OMI alignment of the spots 6 Note The alignment of the SH camera is important the SH spots should be aligned along the rows and columns with a precision of about 1 pixel The OMI body is composed of two pieces a ring that is screwed to the camera using a C mount and the outer body containing the lenslet array The two are attached using 3 setscrews at 120 degrees Illuminate the OMI with the calibration light source Start the exposure and optimize the exposure time using Live and QAuto commands Refer to the image shown below Unscrew the three setscrews at 120 degrees and turn the housing of the lenslet array until the grid is aligned approximately along the camera rows as seen using the image Use the two setscrews on the main body of the sensor for the fine rotation of the grid To do this tighten one and unscrew the other o
34. off all the light sources This step is not critical for the cooled cameras because in this case a shutter is closed in front of the camera window while the dark image is acquired Press the button Dark in the dialog bar on the top of the screen C Sensoft Shack Hartmann wavefront sensor software for Optino EIE File Edit Toolbars Image arithmetic CCD Grid Motor Simulation Window Help Opt Wes EH Anatysis Piot 014 Djuive O A 65 Test Lens Loop Dosia Clatign cai E C Mco V MBEx If the Optino hardware includes a cooled camera a series of 10 dark images will be taken at all the available resolution full 2x2 binning 3x3 binning 9x9 binning and averaged to obtain one dark image to be subtracted from the SH images during analysis The dark image should be acquired when the camera temperature has stabilized around the 0 C If the Optino hardware includes an uncooled camera a seties of dark calibration images for the Shack Hartmann camera will be taken automatically Images of exposure of up to 100msec will be taken with different gain factors About 120Mb of disk space is required to store the images The dark is subtracted from the SH image before the analysis to increase the S N ratio The dark calibration images are stored in the same directory where you installed Sensoft Onote If the dark calibration has not been taken the Sh
35. optical theory The most general form is the one for the Annular Zernike polynomials as the others are a subset and ate obtained by putting the value of the annulus 0 In general the Zernike polynomials involve both cosine and sine terms However for systems with spherical symmetry only the cosine terms are required 165 The task for wavefront analysis then is to find the derivatives of the various Zernike terms to the data and find the coefficients of the various aberrations as well as the zero point offset for each aberration For further details on the polynomials and mathematical expressions see the section on Zernike polynomials used by Sensoft See also the articles by Mahajan given in the bibliography at the end of this section Please contact us if you require the full mathematical expressions 166 12 3 Zernike polynomials used in Sensoft Sensoft gives you the possibility of fitting any of the four polynomials listed above It fits 36 terms in total as detailed in the following table Note that the 36 terms refer to only the cosine terms In the literature when it is mentioned that 36 terms are fit to the data they include both sine and cosine terms The following sections give the expressions for the first nine terms for the 4 set of polynomials For the expressions for the higher order terms please email us at support spot optics com Name m n Number Radial Coma Astigmatism 2 2 Ast3 4 6 8 10 12 14
36. or double pass 4 3 4 1 Light source for illuminating the test element 4 3 4 2 Calibration of Optio ne ne RE A E A A E a qp DEBERET 4 3 4 3 Maximum size that can be tested 4 3 5 Flat surfaces filters in transmission single or double pass 4 3 5 1 Light source for illuminating the test element 4 3 5 2 Calibration of Optino esee 4 3 5 3 Maximum size that can be tested suisses 4 3 6 Lasers single debe e end ied se de Ee Len aee Re binnen 4 4 REPEATABILITY AND ACCURACY OF THE SH TEST sisi 4 4 1 The importance of calibration ss 4 4 2 Repeatability Precision AAD NV WaVefront ERE M 442 2 ernmike COSTFICIENES ee e e o be ee pte le 4 4 3 Accuracy eee 4 4 3 External illumination mode 4 4 3 2 Internal illumination mode 4 5 1 Basic input parameters for the tests eee eene ener trennen enne 58 4 6 INPUT 2 COMA AND SA3 CALIBRATION ALIGNMENT AND FINDING THE CORRECT SEPARATION OF THE OPTICAL ELEMENTS OPTIONAL sccccsssseceessececsssececesscecsesseeecsesaececscsecsesseeecsensececseseecsesaeeecnesaeeeesseeeesenes 59 4 6 1 Additional parameters required for calibration of coma and spherical aberration correction for multi elemert optical syst ms x iu e ric testes tun e ee EROS IR e Sy ee enter UE Rea ER 4 6 2 How Sensoft computes the d
37. run the New Hardware Wizard This wizard will search for an IEEE 1394 Host Controller Click on Next Select Search for the best driver for your device Click on Next The wizard will then ask for locations to search for the driver Clear all of the check boxes and click on Next If asked What do you want to install select The updated driver Click Next When the wizard finds the driver the driver location should be lt WINDOWS path gt inf 1394 inf If the wizard does not find the driver it will need to install it from the Windows program CDROM Click on Finish to complete the installation 3 3 4 2 Installing the camera under Windows 2000 XP To install the camera on a Windows 2000 or Windows XP system you must be logged in with Administrator privileges and Sensoft software should have already installed on your PC If during the installation you receive a message that the digital signature was not found click Yes Connect the camera Windows 2000 XP will not recognize the camera unless it has been previously connected under administrator privileges Restart the PC Windows will search for the driver for the camera module You may need to wait while Windows builds the driver information database If the driver is correctly installed you should find the PixeLINK 1394 Camera for cameras delivered before July 2005 or find the Pixelink Firewire Camera Release 4 during the detection of the driver an
38. s 165 14 7 3 EE 185 CHAPTER 15 OPTINO PRO VS ZYGO GPIXP HR INTERFEROMETER e eeeeee eren 186 15 1 OPTINO PRO Vs ZYGO GPIxP HR INTERFEROMETER A COMPARISON esse 187 CHAPTER 16 DIMENSIONS OF OPTINO cesse ee eee een eese etta sette seta sete seta sesso setas eese seen sea 189 16 1 DIMENSIONS OF OPTINO FRONT FLANGE cceeeeeeeeee eene ener ether sn 190 16 2 OPTINO THE VARIOUS COMPONENTS ss ner nr etre seen rn senes enne 191 16 3 DIMENSIONS OF OPTINO AND BE60 TOGETHER esse 192 INDEX H 193 vii CHAPTER 1 Optino Pro and EE Initial setup and use 1 1 Optino getting started the main steps 1 1 1 How to get started steps to get a good SH image ptino can be supplied either with a cooled SBIG camera or with an uncooled Firewire IEE1394 camera Check which camera your system has Follow the steps for the installation of SensoftOptino from the installation CDROM see Chapter 3 of this manual SensoftOptino must be installed on the PC before you connect the camera for the first time Switch off the PC If the Optino hardware includes a cooled CCD camera Connect the SH CCD to any of the USB ports of your PC using the USB cable provided with Optino Connect the power supply and switch it on Wait until the red led on the back of the cam
39. setup Strictly speaking this condition is generally required only when imaging an off axis object The standard SH test is done for a source placed on axis However in certain cases e g due to space constraints for the very shortest focal ratios this condition may not be satisfied exactly If it is important for your application special optical attachments can be provided for reimaging the pupil exactly on the SH grid Various configurations which can be used for the SH test are described in this section Puntino is used for the tests made with an external source natural star Optino Optino Pro and Optino EE are used for tests made mainly with an internal and external light source 106 Chapter 8 Optino Puntino test configurations 8 2 Test of telescope at Cassegrain focus Parallel light Setup A telescope tested at the Cassegrain focus using parallel light C2 is the collimator of the SH system The incident light illuminating the system should be aberration free In the case of an astronomical telescope a natural star is used with the aberrations due to the earth s atmosphere being removed by integrating the SH image for at least 30 seconds It is not necessary to use parallel light for the test The measured aberrations will then no longer refer to those for parallel light but to one particular optical configuration that is used for the test A beam splitter is used to divert part of the parallel light to a came
40. subdirectory outdir results single The output from the analysis of the test image will help you identifying if there are any problems with the setup analysis Intensity and S N ratio of the spots Check once again the intensity both for the reference and lens image In particular if the flux on the Test image is not giving a good signal to noise the Flux box in the bar on the bottom of the screen will turn to blue color if the image is saturated the flux box will turn to red color Collimation and alignment 14 During the analysis of the test image the collimation and alignment with respect to the calibration are checked again the corresponding Collimation and alignment boxes on the bottom bar will turn to green if OK and to red if KO Test Single lens with collimator Ext illum S pass Ret Use pinhole Fux Collime on Alignment Test Flat mirror Int illum D pass Ret Use flat mirror Flux collimation Alignment Normalized pupil Check if the normalized pupil is around 1 0 or not Sensoft computes the diameter of the SH image as recorded on the camera and compares it with that expected from theoretical computations the expected projected size of the image on the camera computed from the aperture size and the focal length of the elements between the aperture and the lenslet array For accurate computations of the Zernike coefficients the normalized radius should be in the range 0 98
41. that is used 4 3 2 Converging lens in internal illumination double pass spherical mirror beam splitter is used to illuminate the Test optical element from inside Optino reference spherical mirror used at its radius of curvature sends the light back to the Test lens and into Optino Since the light passes through the Test optical element twice the test is done in double pass and the wavefront aberrations are doubled Sensoft takes this into account 4 3 2 1 Light source for illuminating the test element The light source with pinhole is part of Optino 49 Chapter 4 Testing with Optino reference guide 4 3 2 2 Calibration of Optino The calibration of Optino is done by using a flat reference mirror 4 3 2 3 Maximum size that can be tested Without beam expander The size of the input beam D limits the maximum aperture of the lens that can be tested input With beam expander beam expander can be used to expand the beam coming from Optino The standard BE60 allows a beam size of up to 58 5mm Other models allow up to a maximum beam size of 400mm See Motorized beam expanders from Spot optics 50 Chapter 4 Testing with Optino reference guide 4 3 3 Converging lens internal illumination with flat mirror double pass beam splitter is used to illuminate an appropriately chosen collimator C2 that matches the focal ratio of the Test element A flat reference mirror sends the light ba
42. when the large lens L2 is used the arrow points towards the larger exit hole of BE60 and that for the motorized lens L1 points towards the smaller exit hole or towards Optino BE2501 BE2502 BE2503 and BE2504 In this case the lens L2 is small and the arrow should point towards the larger exit hole of BE60 while the lens L1 should point towards Optino For use as a beam compressor follow the above procedure using the table in the section on beam compressors 146 9 7 Examples of getting beams of different output diameter Notes The examples below are for an input beam size D of 6 6mm input Square brackets refer to commands of Sensoft 9 7 1 BE2504 if you wish to have an output beam size of 23 mm Refer to Tables 12 13 and 14 The magnification factor is 3 3 L1 Mount a lens of focal length f11 30mm in the motorized carriage L2 Mount a lens of focal length f11 100mm mounted in position 5 see Table 13 and figure in section 9 3 Take the stepper motor to Home position and move it by 850 steps This will give the approximately correct separation of 124 mm Select the optical setup parameters and Beam expander parameters in the Opt folder Make the light from the BE parallel as explained in Section 9 8 Store the value of the stepper motor position by checking the MBexp box You can go to this position without having to redo the collimation the next time you choose this combination and position 9 7 2
43. 0 950 1000 Wavelength nm 184 14 7 Uncooled camera 6 400 1800nm Vidicon analog camera Maximum spot sampling 30x30 spots 14 7 1 Vidicon IR camera This is a Vidicon camera that can be used from 400nm 1800nm It is an analog camera that uses a video converter for converting the signal to digital form 14 7 2 Characteristics Analog camera Comes with video converter for A D conversion Wavelength range 400 1800nm wavelength range 25 4mm Infrared Vidicon tube 30 30 spots with 300p standard grid 14u pixels effective Size 12 7 mm x 9 5 mm Firewire connection Cable lengths of up to 72m can be used with repeaters Can be run from laptop with a PCMCIA card 14 7 3 Quantum efficiency Spectral Response Characteristics 10 76 2741 03 gt 2 40 2 Visible CCD Video Camera Oo c o 10 3 2 S 10 a Infrared Camera 1075 C5840 10 5 200 400 600 800 1000 1200 1400 1600 2000 Wavelength nm 185 Chapter 15 Optino Pro vs Zygo GPIxp HR interferometer 186 15 1 Optino Pro vs Zygo GPIxp HR interferometer a comparison A small area 7mm of a hard disk platter was tested using the Zygo GPI xp HR interferometer and the Shack Hartmann tester Optino made by Spot optics s r l The results obtained with the two instruments are shown in the table at right the wavelength used for the measurement was 632 nm Table 27 Zygo GPI xp HR OptinoPro Difference P V nm
44. 1 02 The normalized radius computed by Sensoft during the analysis is displayed on the image bar that appears on the display If the normalized radius is in the correct range the background of the box is green otherwise the background of the box is red Normalized radius OK Current reference Ref0002 fit b Last image analyzed Good_RGP_14 fit te Normalized radius not OK Good_RGP_14 fit Current reference Ref0002 fit b Last image analyzed If there is a difference either the optical parameters in Opt Properties have been specified wrongly or the light that is falling on the grid is converging or diverging Check the optical parameters specified and or the collimation Sections 1 2 7 and 1 3 The program assumes that the collimation has been done before the acquisition of the Test image a dialog is displayed suggesting the modification to be applied to the optical parameters in order to get the correct normalized radius The dialog is shown in the figure below 15 Recompute normalized pupil Normalized pupil is the recommended range 1 02 Normalized pupil computed with user defined parameters 1105 F computed with user defined parameters 10 00 Recommended F of optical system Please change the aperture and orthe focal length to get the correct F indicated above Aperture of test optic mm 10 00 Effective focal length distance to image plane of test optic mm Focal leng
45. 354 9 BE6002 11 4 7 0 21 416 0 354 9 BE6003 10 5 9 0 17 401 9 354 9 BE6004 7 1 0 14 3918 354 9 BE6005 8 9 0 11 380 2 354 9 145 9 6 Changing the BE lenses 9 6 1 How to change the BE lenses Different expansion or compression factors can be obtained by choosing the appropriate combination of lenses see Sections 9 3 9 4 and 9 5 by the following procedure Note the input beam for your instrument In double pass the internal light source of Optino is used in which case the beam size is either 6 6mm uncooled camera or 9mm cooled SBIG camera Knowing the beam diameter required for the output beam DBE compute the magnification factor M Go to the table in the section of Beam expander and choose the appropriate values of the focal lengths for the fixed and motorized lens Carefully remove the lenses that may have been already mounted by first unscrewing the hex screws using a metric Allen key Then cover the lens mounting with a protective cover and using both hands carefully slide the lens mounting out Since precise pins are used for positioning a steady even force will be required When inserting the lens take care to position the two pins in the corresponding holes and apply even pressure to push the mounting in Tighten the hexscrews Take care to point the lens mounting with the arrow shown on top of the lens mounting pointing in the direction of parallel light BE6001 BE6002 BE6003 BE6004 and BE6005 For the case
46. B2 connection Cable lengths of up to 500m can be used with repeaters 14 1 1 3 Cooled Camera 3 good general purpose cooled camera This camera has a large pixel size and is ideal for situations where a cooled camera and fast readout is required 0 5 seconds Since it has a cooled CCD chip long integration times can be used This is useful when the light source is weak or when a narrow band filter is tested Main features Digital camera Wavelength range 350 1100nm Cooled CCD chip 30 30 spots with 300 standard grid Large 20u pixels Size 10 2x10 2mm USB2 connection Cable lengths of up to 500m can be used with repeaters 177 14 1 1 4 Cooled Camera 4 for very large sampling This is a large format camera recommended for use when a very large sampling on the pupil is required Relatively slow read out Since it has a cooled CCD chip long integration times can be used This is useful when the light source is weak or when a narrow band filter is tested Main features Digital camera Wavelength range 325 1100nm Cooled CCD chip 50x50 spots with 300 standard grid 16u pixels Size 20 5 mm x 16 4 mm USB2 connection Cable lengths of up to 500m can be used with repeaters 14 1 1 5 Cooled Camera 5 for largest possible sampling This is a large format camera capable of giving the largest possible sampling on the pupil It has a slow read out Since it
47. C1 and a second camera This is used to acquire the star for an astronomical telescope as well as to get out of focus images of the telescope pupil It gives additional information on the telescope quality like zones on the mirror surface and seeing Instrument Puntino Optino It can be adapted to different focal ratios Calibration The aberrations of the SH system itself are removed by taking a calibration image with a calibration source placed at the focus of C2 Input Values for wavefront analysis D ex aperture of test element fley focal length of test element 7 focal length of collimator col Output information 109 Along with the Zernike coefficients the wavefront and optical quality Sensoft gives diagnostics for correcting defocus and spherical aberration by moving M2 and shifting the focal plane These corrections can be based on analytical formulae or on a lookup table provided by the user for any optical element in the system Information can be obtained of dome and mirror seeing by examining the plot of the residuals Single or double pass Single pass Note that since reflection doubles the aberration the mirror surface is half the wavefront computed by Sensoft and has opposite sign 110 8 4 Test of single lens in parallel light using external illumination Parallel light Setup In this configuration aberration free parallel light falls on the lens L being tested and comes to a focus
48. Distance from edge of mounting of L1 to middle of hole holding Hole Lens L1 in middle Lens L1 towards L2 Lens L1away from L2 position mm mm mm BE25 first 7 set of holes towards motor 94 76 112 1 1 2 3 4 5 6 7 124 106 142 139 121 157 154 136 172 BE60 last 4 sets of holes towards the larger exit hole of BE 386 368 404 396 378 414 416 398 434 B8 The middle position of the lens corresponds to about 850 steps from Home position of the stepper motor 144 9 5 Beam compressor 9 5 1 Beam expander used as beam compressor The beam expander can also be used as a beam compressor to illuminate and test small elements In double pass use the internal light source of Optino for the test For use in single pass use an external illumination see Chapter 9 The Motorized Calibration Unit ECM Connect it to Optino with the BE using the larger normally the exit hole when used as a beam expander hole The motorized lens will face away from Optino towards the light source The tables below give the details Also see section 4 9 and Chapter 8 on Beam expanders 9 5 2 BE25 used as beam compressor Table 15 BE25 used as beam BE pos Comp 1 BE2501 4or5 1 5 0 66 118 7 75d 0 BE2502 2 ot 3 2 0 0 50 84 0 60 0 BE2503 25 0 4 93 7 75 0 4 BE2504 3 3 0 3 121 5 50 100 0 9 5 3 BE60 used as beam compressor Table 16 BE60 used as beam compresses BE pos Comp BE6001 11 4 2 0 24 495 7
49. Fringe Zernike polynomials gy DE Gr 2r cos g 9 Quadratic astigmatism 170 12 7 Expressions for the 8 Seidel polynomials Do not include normalization factor Not orthogonal to each other in the wavefront space Do not include obscuration factor Table 24 Name Er 1 3 3rd order Spherical aberration p r 5th order Spherical aberration FEE Triangular coma r cos 30 P Quadratic astigmatism ri cos 49 Astigmatism cos 29 Q 171 12 8 Common notation of Zernike polynomials Zernike polynomials are commonly expressed in the form of cosine and sine terms as shown in the table below Table 25 Term Name 71 Constant Standard Zernike polynomials 1 1 2 3 4 5 7 DN 15 15 16 72 Z Z Z Z Z7 Z8 Z9 Z10 Z11 Z12 Z13 Z14 Z15 X Tilt 45 deg 3rd order Astigmatism X coma Y coma X Triangular Coma X clover Y Triangular Coma Y clover 3rd order Spherical Aberration Sphere 5th order X Astigmatism Sphere 5th order Y Astigmatism X Quadratic astigmatism Ashtray Y Quadratic astigmatism Ashtray 2rcoso B 3 X Tilt 2rsing B 4 Defocus Bar 1 5 5 0 deg 3rd order Astigmatism V6r 2 6 V6r 2 V8 3r 2 V8 3r 2r sing V8r 3 J8r 3 V5 6r 6r 1 V10 4r 2 cos29 V10 4r 3r sin29 10r cos 4p 10r sin4g
50. In case the connections are not made properly the green light on the hub will not be lit For the SBIG cameras repeaters can be used to increase the cable length to up to 50m 3 5 Using Sensoft Optino Connect the camera module to the OHCI card using the supplied 1394 cables The hardware key must be attached to the to USB port The content of the subdirectory Dark contained in the installation CDROM should be copied into the directory where you installed Sensoft Click on the SensoftOptino icon that is added to the All Programs task bar in the start menu 44 Chapter 4 Testing with Optino reference guide 45 4 1 The Shack Hartmann method 4 1 1 General introduction The basic concept behind the Shack Hartmann test is the following Take a SH image called Test image The positions of the spots as recorded by the camera depend on the aberrations from Test element SH system Auxiliary optical elements like beam expander Take a second SH image called reference image The positions of the spots as recorded by the camera depend on the aberrations from SH system Auxiliary optical elements The difference between the two gives the aberrations of the Test optical element Thus the whole SH analysis consists of the following steps Choose the appropriate optical setup for the optical element called Test that you are testing Automatically adjust the exposure time and take a Ref reference image
51. LAR ZERNIKE POLYNOMIALS see 168 12 5 EXPRESSIONS FOR THE FIRST 8 TERMS FOR STANDARD ZERNIKE POLYNOMIALS eee 169 12 6 EXPRESSIONS FOR THE FIRST 8 TERMS FOR FRINGE ZERNIKE POLYNOMIALS see 170 12 7 EXPRESSIONS FOR THE 8 SEIDEL POLYNOMIALS sens enne enne enne 171 12 8 COMMON NOTATION OF ZERNIKE POLYNOMIALS anses rennen enne enne entere 172 CHAPTER 13 REFERENCES 173 13 1 REFERENCES ne ee iet eu tene 174 CHAPTER 14 CAMERAS AVAILABLE WITH OPTINO AND 14 1 SUMMARY OF DIFFERENT CAMERAS AVAILABLE WITH OPTINO AND PUNTINO ss 14 1 1 Cameras for the visible region 300 1100nm esee eene 14 1 1 1 Uncooled Standard Camera 1 general purpose real time camera 14 1 1 2 Cooled Camera 2 for large wavelength range coverage from UV to near IR 14 1 1 3 Cooled Camera 3 good general purpose cooled camera 14 1 1 4 Cooled Camera 4 for very large sampling eere 14 1 1 5 Cooled Camera 5 for largest possible sampling eee 14 1 2 Camera for the IR region 400 1800nm ss T4 1 2 1 UrncooledC met tcr esed tees 14 2 UNCOOLED STANDARD CAMERA 1 375 1064NM 23X23 SPOTS sse 14 2 1 Standard digital camera with high quality CMOS sensor 14 22 CHATACICLISTICS ES EET DURER TEE 14 2 3 QuantumczeffiCleCy sei cues sys stateme
52. Optino Users Manual Wavefront sensor for laboratories And manufacturing environment Version 6 3 October 2005 Copyright 2005 Spot optics s r l All rights reserved Spot optics srl Via Turazza 48 35128 Padova Italy Phone 39 049 8078529 Fax 39 049 8087861 www spot optics com Includes user manuals Optino Shack Hartmann wavefront sensor Optino EE Optino Pro Optino Uno and OMI Motorized beam expanders BE Extemal Motorized calibration Unit ECM Table of Contents CHAPTER 1 OPTINO PRO AND EE INITIAL SETUP AND USE ssssnneenesse 1 1 1 OPTINO GETTING STARTED THE MAIN STEPS sense 2 1 1 1 How to get started steps to get a good SH image rene 2 1 Z OPTINO DETAILS OF SETUP AND USE spe rrt rere ER HEX rene nes ont Fe bee EDS Se FOU 4 1 2 1 Operate the stepper motor to get parallel light 4 1 225 etup th cameras nine ones d Be CR gue a e ose EU UE 5 1 2 3 Align the Shack Hartmann camera sise 6 1 2 4 Take the dark calibration for the Shack Hartmann camera ss 7 1 2 5 Take a reference image clicking on the Ref button on the dialog bar 7 1 2 6 On line and off line acquisition and analysis of reference SH images 10 1 2 7 Align the SH image from the optical system being tested with respect to the reference image taken in Section 2 5 ep Re ee Ne de E etre 12 1 2 8 Collimate the light from the optical system being tested ss 13 1 2 9 Recheck the alignment section 1 2 7
53. Optino automatic Ifyou have Optino Pro or Optino EE launch Sensoft Goto WFS ECM and choose the serial port to which the motor is connected Using the ECM toolbar click the Focus button The motor will automatically go to the nominal focus position 152 Feed the light from ECM25S to OMI or to the Test element see Chapter 6 Optino Test configurations Use the Live command to start the exposure Adjust the exposure time to get the right flux in the spots maximum counts 255 using the QAuto command next to Live Center the SH image Alternatively use the Mcoll command to let Sensoft do the collimation automatically Collimation can also be done manually see below 153 es ne 188 saritl CVA fv eov LX parallel it with Manual Please see the commands for controlling the stepper motor of ECM using Hyperterminal Chapter 8 Communication protocol for stepper motor of Optino Puntino BE and ECM If you have OMI launch the Windows program Hyperterminal to be found under Accessories Communications Give the command D1225 to move the stepper motor to 1225 which is the nominal focus of the 75mm focal length collimator Feed the light from ECM25 to OMI or to the Test element see Chapter 6 Optino Test configurations Use the Live command to start the exposure Adjust the exposure time to get the right flux in the spots maximum counts 255 using the QAuto command nex
54. RE Be e te 131 CHAPTER 9 MOTORIZED BEAM EXPANDERS FROM SPOT OPTICS 133 9 1 MOTORIZED BEAM EXPANDERS FROM SPOT OPTICS eee 134 9 1 1 Motorized beam expander principles 134 9 1 2 ad e epe adn uad em dnd 135 9 3 Beam compressot suas e e eo a a e e eb rim Wines repre dates 135 9 1 4 Use in single pass and double pass ss 135 9 2 DIFFERENT MODELS OF THE MOTORIZED BEAM EXPANDERS FROM 136 i a 136 9 2 2 Coupling the beam expander to 137 93 MAGNIFICATIONS AVAILABLE ie t REO entre titre ede DD entente is 138 93 I Different models ayatlable manteau ete te eh rete rete teet htt 136 9 3 2 BE25 The lens positions and magnifications esee eee eene 138 9 3 3 BE60 The lens positions and the magnifications ss 139 9 3 4 BE25 and BE60 summary of magnifications available ss 140 9 3 4 1 Input beam diameters 9mm and 6 9mm ses 9 3 4 2 Input beam diameters 8 5mm and 6 6mm 9 4 HOW TO GET DIFFERENT MAGNIFICATIONS rene rennen trennen 9 4 1 The different mounting holes for the lenses ss 142 9 4 2 Summary of lens positions esee o ee rebate nn lentes 144 9 5 BEAM COMPRESSOR tee crit oe tr n ede get eo ge he IRE GER INE Gee foe nds 145 9 5 1 Beam expander used as beam compressor
55. ack Hartmann analysis will stop without producing any output 1 2 5 Take a reference image clicking on the Ref button on the dialog bar In the first page of the SH Directories folder define the path for the directory where you would like Sensoft to store the output results outdir_results When you select a new directory the reference and lens image fields will be reinitialized with blanks Shack Hartmann C sensof REF_flat0001 fit Select Lens imaqefs CAsensofiNG amp T0001 fit Prefix for lens image s Lens Switch on the fiber optic light source illuminating the calibration unit provided with Optino Check the Live and the QAuto box in the dialog bar and let Sensoft optimize the exposure time of the image Sensoft Shack Hartmann wavefront sensor software for Optino File Edit Toolbars Image arithmetic CCD Grid Motor Simulation Utilities Window Help Opt wr s SH Anatysis Piot mies e Loop asi Oain 7 coit E Mco In OptinoPro and OptinoEE version the collimator is motorized and you can get parallel light for the tests by moving it by clicking on the MColl button in the dialog bar Before this a flat mirror should be mounted on the front flange of Optino to send the light back into the instrument The setup for the movement of the collimator can be specified in the Dialog that is opened au
56. al surfaces single pass O Telescope at Cassegrain Coude focus Mirror ar radius of curvature O Telescope at Prime Newtonian focus i O Flat mirror Ll Use Bexp Lens Multi element system single pass Flat surfaces double pass 8 With collimator j O With pinhole O Flat mirror H Use Bep OFilterwedge Use Bexp Check here ifthe optical system is multi element Lens Multi element system double pass Other Flat mirror O With collimator and flat mirror Parallel light With parallel light and spherical mirror v Use Bexp O Laser Check here ifthe optical system is multi element v Testmode Properties Description Calibration Optical element under test Aperture of test optic mm 20 5 Effective focal length distance to image plane 270 of test optic mm Normalized central hole 0 Aspherical element V Puntino Optino Focal length of collimator mm 85 Reference wavelength nm 470 Diameter of input beam from Optino mm 6 9 Description Switch on the light source for illuminating Optino place a flat mirror at the exit hole of Optino to send light back to the lenslet array Exposure unit is msec for the uncooled camera and sec for the cooled camera If Optino is using an uncooled camera start with a 10msec exposure If Optino is using a cooled camera start with 11sec exposure Cl
57. als for Actual Quality AQ Potential Quality PQ and Residual Quality RQ Before doing the Analysis you should close the Excel window in order to allow Sensoft to overwrite the xls file when the analysis is launched Sensoft checks if the file is open in an Excel application and asks you to close it The file created by Sensoft is compatible only with the Excel version included in Office XP An example of output Excel file is shown on the next page 103 Microsoft Excel PN 10 BZU f E Ele Edit View Insert Format Tools Data Window Help B 6 E JEUX gt UJ y m on Q gt 3rd order Spherical Triangular Coma Quadratic Astigmatism PN21 28 11 2003 10 53 44 Coef 16 1865 9 53 3 1 3 55 3 314 28 1 4 27 386 1 4 36 246 9 4 36 246 9 M 4 gt MXPMir Sheet Sheet2 Sheet3 1 28 11 2003 10 58 07 446 3 2843 6 19 1 124 58 2 20 2 2 4 34 341 4 3 86 310 5 3 86 310 5 28 11 2003 11 14 26 198 6 813 3 20 9 8 44 8 13 8 13 2 4 09 413 8 4 08 241 6 4 08 241 6 Chapter 8 Optino Puntino test configurations 105 8 1 General comments on the optical setup for testing with Optino and Puntino he general principle of the SH method consists of forming an image of the exit pupil of the optical element or system being tested on the SH grid Puntino and Optino follow this design constraint for a standard optical
58. and in the next section we discuss how Sensoft can be used for checking if the setup has been correctly done The following procedure is recommended The optical system should be mounted along the optical axis of Optino and the collimator mounted on it The flange of Optino can be used as a reference plane There are precise mounting holes of diameter 4mm tolerance H7 that should be used The illumination source say a fiber should be mounted such that it is at the mechanical center of the collimating lens when taking a reference image The illumination source say a fiber should be mounted such that it is at the mechanical centet of the optical system when taking the test image However if the fiber is being aligned with respect to the optical system then it should be mounted at the nominal mechanical center of the optical system with the possibility of x y adjustment 85 between the fiber and the collimator optical system should be kept under tight control by relying on strict mechanical tolerances 5 3 Using Sensoft for checking the alignment Sensoft computes the ellipticities of the spots and plots it as a 3D distribution or as a contour plot If the test system is not correctly aligned with respect to the fiber then you will get a plot that will show an asymmetry see below You should adjust the fiber until you get a symmetrical plot P V 0 709 ave 0 553 rms 0 128 Ellipticity
59. ander if used Output information Along with the Zernike coefficients wavefront and the optical quality Sensoft gives diagnostics for correcting defocus Other output M and Single or double pass Single pass 114 8 7 Test of concave mirror To SH System Radius of ES curvature F C2 of TT spherical mirror Spherical mirror Setup In the above configuration light is made parallel by the collimating lens C1 and passes through the beam splitter After passing through the collimator C2 it comes to a focus at F which is also the radius of curvature of the spherical mirror The focal ratio of the lens C2 should be twice that of the focal ratio of the spherical mirror as it is being tested at its radius of curvature The spherical aberration of a mirror at its center of curvature is given by r 2R ASA K Here ASA is the angular spherical aberration diameter of image at best focus in radians K the conic coefficient of the mirror r the ray height on the mirror and R the radius of curvature Spherical mirrors have zero ASA K 0 while parabolic amp 1 and hyperbolic K 1 mirrors have large positive spherical aberration However Sensoft is capable of testing mirrors with hundreds of wavelengths of aberrations Instrument Optino The collimator C2 can be changed easily to match the focal ratio of the spherical mirror Calibration The aberrations o
60. arameters page you will have to manually check the override automatic box in the SH Analysis parameters page 19 Shack Hartmann Directories Zernikes Analysis parameters Utilities Graphics Centroiding Threshold Override automatic Ellipticity cutoff Reference 0 105 F 07 Lens 0 7 Range 0 05 0 5 Range 0 1 1 0 1 2 14 Do an analysis in a continuous loop The continuous loop is useful for monitoring the variation in the analysis while changing the analysis conditions either in the ambient where the test take place or in the optical setup In this section we describe how you can get the analysis in a continuous loop Click on the button close to the Loop box in the dialog bar The dialog displayed in the next page will be opened Loop param x Range of alert values for aberration coefficients From To Defocus 50 Tilt 0 50 Coma nm 0 50 Sa3 nm 0 50 Ast 0 50 Tricoma 0 50 QAst nm 0 50 5 nm 0 50 nm 0 50 Ast5 0 50 Select type of plot for loop Contour O3D O Aberrations O Align Coma Ast O Spot diagram OPesiduals O mif SH image 2 2 v Displ Image stretching factor isplay g g Ox Archive results of analysis Save coefficients in log file Serial communication of coefficients Without sending coefficients Send coefficients to Ocom CO cow
61. berration by changing the separation between the mirrors and shifting the focal plane These corrections can be based on analytical formulae or on a lookup table provided by the user for any optical element in the system As can be seen the correction for defocus and spherical aberration are obtained using the same movement of M2 The spherical aberration measured by Sensoft refers to the best focal plane See Help Information can be obtained of dome and mirror seeing by examining the plot of the residuals Single or double pass Single pass Note that since reflection doubles the aberration the mirror surface is half the wavefront computed by Sensoft and has opposite sign 108 Chapter 8 Optino Puntino test configurations 8 3 Test of telescope at Prime Newtonian focus Parallel light Setup A telescope tested at the Cassegrain focus using parallel light C2 is the collimator of the SH system The incident light illuminating the system should be aberration free In the case of an astronomical telescope a natural star is used with the aberrations due to the earth s atmosphere being removed by integrating the SH image for at least 30 seconds It is not necessary to use parallel light for the test The measured aberrations will then no longer refer to those for parallel light but to one particular optical configuration that is used for the test A beam splitter is used to divert part of the parallel light to a camera lens
62. cal elements The advantages of a motorized beam expander are explained below 4 9 2 Main advantages The motorized lens ensures that parallel light is obtained easily Almost any magnification can be obtained by changing the lenses L1 and L2 ensuring the maximum beam sampling of the optical element A filter can be used with the fiber optic light source Thus the beam expander can be used at any wavelength see Optino Pro and EE Initial setup and use Diverging or converging light can be obtained to illuminate the Test optical element Where Choose in Opt Beam Expander What to choose Beam expander factor to get the expanded beam size that you wish to have Then choose the two right lenses to use in the beam expander See below and separate section on beam expander 66 Note The significance of fl and change due to the optical test setup when the BE is used In this case flus fi and fla 7 fh where fl is the focal length of the BE lens facing the optical element and fl is the focal length of the BE lens towards Optino see section on BE The residuals encircled energy spot diagram etc computed by Sensoft are automatically scaled to the focal length of the test optical element The tables in the next page show the different magnifications available Please see Chapter 9 Motorized beam expanders from Spot optics Table 6 BE25 Maximum output diameter DBE 23mm No Name BE p
63. cal parameters for the tests 4 5 1 Basic input parameters for the tests The following parameters are required for both internal illumination and external illumination Symbol Quantity All tests D Table 4 Diameter of the beam both for internal or Opt external illumination This is model dependent and can have the value of 5 5 6 6 9mm internal illumination or 23mm external illumination input Aperture of the optical element to be tested Test wavelength Normalized central hole if any normalized with respect to the aperture of the test optical element Orientation of the optical element e g NSEW WES for astronomical telescopes or LURD Left Orientation Up Right Down in the laboratory Converging elements 1 5 above plus fu Focal length of the collimator attached to Opt Optino Puntino Focal length of the optical element to be tested Opt Lasers 1 5 above plus 8 0 Nominal full angle of divergence Opt If using beam expander M Magnification factor of Beam Expander if Opt used Focal length of motorized lens of Beam Opt expander Focal length of fixed lens of Beam expander Opt 58 4 6 Input 2 Coma and SA3 calibration alignment and finding the correct separation of the optical elements optional 4 6 1 Additional parameters required for calibration of coma and spherical aberration correction for multi element optical systems powerful feature of Se
64. camera as well as the Quantum Efficiency QE curves are given in the following sections 14 1 1 Cameras for the visible region 300 1100nm 14 1 1 1 Uncooled Standard Camera 1 general purpose real time camera This is the standard camera for Optino It is useful for all general purpose testing where speed is important Requires a bright source for the test as the maximum integration time is about 100ms Main features Digital camera Wavelength range 375 1064nm Uncooled CMOS chip 23x23 spots with 300 standard grid Tu pixels Size 9 6 mm x 7 5 mm Firewire connection Cable lengths of up to 72m can be used with repeaters Can be run from laptop with PCMCIA card 176 14 1 1 2 Cooled Camera 2 for large wavelength range coverage from UV to near IR This camera is ideal for use over a very large wavelength range 325 1100nm because of its small pixel size giving ample sampling over the full wavelength range It is also has a good blue sensitivity Since it has a cooled CCD chip long integration times can be used This is useful when the light source is weak ot when a narrow band filter is tested Because of the large number of pixels it has a relatively slow read out time of 8 7 seconds full frame Main features Digital camera Wavelength range 325 1100nm Cooled CCD chip 30 30 spots with 300p standard grid Large 20u pixels Size 10 2 10 2mm US
65. ccount the possible presence of a central obscuration Fringe Zernike polynomials The Fringe Zernike polynomials differ from the Standard Zernike polynomials as they are not normalized on the pupil Used by people in the field of interferometry Seidel polynomials The Seidel polynomials are the extension of Seidel aberrations from geometrical optics There are two important differences between the Zernike and the Seidel polynomials Annular Standard Fringe Zernike polynomials take into account the contributions from lower order aberrations of a similar nature see table below For example the term for 3 order spherical aberration contains a defocus term shift of focal plane along the optical axis and that for coma contains a tilt term shift perpendicular to the optical axis This minimizes the rms error on the waveftont While Annular Standard Fringe Zernike polynomials are orthogonal to each other in wavefront space Seidel polynomials are not The first three sets are basically the same and derive from the work of Zernike Their use reflects the different fields in which they are predominantly used For example as the name suggests Fringe polynomials originated in the field of interferometry and are used by Zygo Inc The annular Zernike polynomials on the other hand are used in astronomical wavefront sensors as usually there is an obscuration by the secondary mirror of the telescope Seidel polynomials originate in classical
66. ck to the Test lens the collimator C2 and into Optino 4 3 3 1 Light source for illuminating the test element The light source with pinhole is part of Optino 51 Chapter 4 Testing with Optino reference guide 4 3 3 2 Calibration of Optino The calibration of Optino collimator C2 is done by using a spherical mirror 4 3 3 3 Maximum size that can be tested Without beam expander The size of the input beam D limits the maximum aperture of the lens that can be tested input With beam expander beam expander can be used to expand the beam coming from Optino The standard BE60 allows a beam size of up to 58 5mm Other models allow up to a maximum beam size of 400mm See Motorized beam expanders from Spot optics 52 Chapter 4 Testing with Optino reference guide 4 3 4 Flat surfaces mirrors internal illumination single or double pass Flat mirrors can be tested in the internal illumination mode either in single pass as shown below ot in double pass as in the Ritchey Common test 4 3 4 1 Light source for illuminating the test element The light source with pinhole is part of Optino 4 3 4 2 Calibration of Optino A high quality flat mirror is used for calibrating the aberration of Optino 4 3 4 3 Maximum size that can be tested A beam expander can be used to expand the beam coming from Optino The standard BE60 allows a beam size of up to 58 5mm Other models allow up to a maximum bea
67. component lens using a collimator and a flat mirror internal illumination Setup In the above configuration light is made parallel by the collimating lens C1 and passes through the beam splitter It comes to a focus at F after passing through the collimator C2 This is also the focus of the multi element lens L under test It falls on a mirror M which should be of a high quality say 4 4 4 10 or A 20 depending on the accuracy required for testing the lens L The mirror should have a minimum diameter equal to that of the lens L and the focal ratio of the lens C2 should match that of the lens L Instrument Optino The collimator C2 can be changed easily to match the focal ratio of the lens L Calibration The aberrations of the SH system itself are removed taking a calibration image of a small high quality like for the flat mirror above spherical mirror instead of the lens L Input Values for wavefront analysis input diameter of beam from Optino Ds diameter of test element fles focal length of test element focal length of collimator C2 Output information Along with the Zernike coefficients wavefront and the optical quality Sensoft gives diagnostics for correcting defocus coma by aligning the elements and spherical aberration by changing the 121 separation between the elements These corrections can be based on analytical formulae or on a lookup table provided by the user for any optical elemen
68. ct Mirror images CAsensof amp TDKMest NTBTI fit In the SH Zernikes select the Zernike terms that you want to fit to the data if you want wavefront or surface reconstruction and the Actual Quality definition that you prefer Subtraction of Tilt only or subtraction of tilt and defocus In the SH graphics section select the graphs that you want to see at the end of the analysis Press the Analysis button in the dialog bar at the top of the screen Note If the image has been previously analyzed all the output files generated by the previous analysis will be overwritten See Help for other details See also the hardware manual for adjusting Optino and trial run and troubleshooting in Help 1 2 16 Check the Actual Quality Potential quality and Residual Quality Sensoft defines Actual Quality Potential Quality and Residual Quality as follows Actual Quality Abbreviated as AQ This is obtained after subtracting the contribution of tilt only ot tilt and defocus as computed from the Zernike polynomials from the data The wavefront as well as other parameters Encircled Energy Strehl Ratio are also given Potential Quality Abbreviated as PQ This 1s obtained after subtracting the contribution of the first 7 Zernike terms tilt defocus coma astigmatism spherical aberration quadratic astigmatism and triangular coma from the data The wavefront as well as other parameters Encircled Energy Strehl Ratio are also given
69. d Generic 1394 Desktop Camera module installed under the Imaging Device group in the Device Manager of the System Panel Control Panel 43 3 4 Miscellaneous 3 4 1 Upgrading the camera driver In the System Panel Control Panel go to the Imaging Device group in the Device Manager if you find the PL_A630 module you need to upgrade the driver Select the Imaging Device group in the Device Manager of the System Panel Control Panel Select the Properties of the PL A630 entry In the Driver page press the button Update Driver Select the CDROM unit containing the Sensoft Optino installation CDROM to detect the new driver Atthe end of the upgrade you should find the PixeLINK 1394 Camera module installed 3 4 1 1 Windows 2000 XP only To upgrade the drivers on a Windows 2000 or Windows XP system you must be logged in with administrator privileges Connect the camera at installation time Windows 2000 XP will not recognize the camera unless it has been previously connected under administrator privileges 3 4 2 Using the camera with hubs for long cable lengths The standard cable supplied with the IEEE 1394 based Imaging module is of a length of 2m Using repeaters that connect cables of length 4 5m a cable length of up to 72m can be obtained 14 repeaters The hub gets its power supply from the PCI card In the case of a laptop a power supply of at least lamp should be used Each hub consumes 3W
70. e or double pass Double pass 124 8 13 Test of multi component lens in parallel light using a spherical mirror internal illumination Beam splitter Light source with pinhole Setup In the above configuration light is made parallel by the collimating lens C1 and passes through the beam splitter It falls on the element L being tested and comes to focus at It is then reflected back into the system by the spherical mirror S The accuracy of the tests depends on the quality of the spherical mirror and the flat mirror used for the calibration Instrument Optino Beam expander A beam expander can be used to expand or compress if required for very small test elements the size of the output beam Calibration The aberrations of the SH system are removed by taking a calibration CCD image with a good quality flat mirror in parallel light before it falls on the lens L Input Values for wavefront analysis D npu input diameter of beam from Optino Ds diameter of test element fles focal length of test test test element M magnification or compression factor of beam expander if used 125 Output information Along with the Zernike coefficients wavefront and the optical quality Sensoft gives diagnostics for correcting defocus coma by aligning the elements and spherical aberration by changing the separation between the elements These corrections can be based on analytical formulae or o
71. e spot is defined as 7 1 b a where b and a are the major and minor axes of the spot 0 corresponds to a round spot This parameter is defined in the section under SH Analysis parameters Shack Hartmann Directories Zemikes Analysis parameters Utilities Graphics Centroiding Threshold Override automatic Reference 0 105 Fj Lens 0189 Ellipticity cutoff Range 0 05 0 5 Range 0 1 1 0 1 2 12 Do a Test analysis Click the Test button in the dialog bar on the top of your screen for doing a test SH analysis E Sensoft Shack Hartmann wavefront sensor software for Optino Edit thmet C Motor jr le oobars Image a mulation Utilitie T 000 Lie lau Loop osion Cation coi mco Sensoft will acquire a test image and analyze it The centroids of the spots are detected using an automatic procedure to find the best cutoff threshold value in the image Sensoft will then combine centroids from reference and test image and fit the default 7 Zernike polynomial terms defocus tilt coma 3 order spherical astigmatism triangular coma quadratic astigmatism The image displayed on the screen is also saved in the directory outdir_results under the default name Test0001 fit You can specify a different name in the dialog bar that is displayed after you press the test button The output results are stored in the
72. efront analysis D ppu input diameter of beam from Optino diameter of test element M magnification or test compression factor of beam expander if used Output information Sensoft gives the Zernike coefficient the wavefront and optical quality of the flat mirror Single or double pass Single pass 117 Chapter 8 Optino Puntino test configurations 8 9 Test of flat mirror double pass Setup In the above configuration light is made parallel by the collimating lens C1 and passes through the beam splitter It then illuminates the Test flat mirror is reflected to the reference flat mirror and then back into Optino Instrument Optino Beam expander A beam expander can be used to expand or compress the size of the output beam Calibration The aberrations of the SH system itself are removed taking a calibration image of a high quality flat reference mirror instead of the test mirror This determines the accuracy of the test Input Values for wavefront analysis Dip input diameter of beam from Optino Des diameter of test element M magnification or compression factor of beam expander if used Output information Sensoft gives the Zernike coefficient the wavefront and optical quality of the flat mirror Single or double pass Double pass 118 Chapter 8 Optino Puntino test configurations 8 10 Test of single lens using a collimator and a flat mirror internal illumination
73. er 4 12 2 3 PQ Potential quality For all the elements this refers to the quality of the optical element after the subtraction of the conttibution of the first 7 Zernike coefficients tilt defocus 3 order coma 3 order spherical aberration 3 order astigmatism triangular coma and quadratic astigmatism Thus in a single analysis the user can see the current quality of the optical element the potential quality of the optical element as well as focus on any individual aberration of interest by not fitting it to the data 4 12 3 What to look for The first important parameter to check after the analysis is done is the normalized radius which as explained in Section 4 10 should be 1 75 The second parameter to check is the Probability of goodness of fit This gives an estimate of how well the Zernike coefficients chosen to fit to the data approximate it If it is not 1 then Not enough Zernike coefficients are fit to the data There are terms in the data that cannot be well approximated by Zernike polynomials The data is noisy 4 12 4 Zernike coefficients The output table gives the values of the Zernike coefficients in nm Cx coefficient in x direction Cy coefficient in y direction C Total coefficient Angle the orientation of the aberration in degrees The angle is measured from the x direction of the SH image The values of the total coefficient are displayed on a red or green background the bac
74. er Consequently the shape of the optical surface is negative of the wavefront Whenever there is any reflection or the light passes through the lens being test twice the wavefront aberration is doubled 163 In general the expression for the Seidel polynomials can be written as cosm Q Po Here nis the power of the radial term and m defines the degree of the azimuthal term is the zero point offset for each aberration For example n 2 m 0 represents defocus and 3 m 1 refers to coma Zernike polynomials on the other hand involve aberration balancing For example when spherical aberration n 4 0 is fit to the data a defocus term is also fit to minimize the rms wavefront error There are a number of excellent articles and books on the subject some of which are listed in the Chapter References 164 12 2 The different Zernike polynomials in use There are a number of Zernike polynomials in use Annular Standard Fringe Seidel The different expressions are given in the following pages The program is capable of fitting four sets of polynomials to the slopes Annular Zernike polynomials Annular Zernike polynomials are based on diffraction theory and take into account the presence of the central obscuration in the mirror lens image Standard Zernike polynomials The Standard Zernike polynomials are the Annular Zernikes defined in the diffraction theory they do not take into a
75. era box is on When you launch Sensoft go to the section and select to connect the camera The temperature regulation will be automatically started and the camera temperature will be regularly refreshed in the status bar on the bottom of the display Wait until the temperature is close to 0 C If the Optino hardware includes an uncooled FireWire camera Connect the digital FireWire camera to the FireWire PCI adapter or a built in FireWire port card in the case of a PC or to the PCMCIA FireWire adapter card dongle in case of the laptop using a FireWire cable with a 6 pin to 6 pin connectot Connect the stepper motor of Optino to the serial port of the computer using a 9 pin serial cable Connect a 12V 500mA powet supply inner polarity positive to Optino power supply for the stepper motor of the collimator Switch on the PC Launch Sensoft Optino and fill in the parameters in the Opt section In Opt Ext Illum test or Opt Int Illum test select the test setup in Opt Properties enter the optical parameters for the optical system that you want to test in Opt Desctiptions select the description of the Project that will appear as title in the output files created by Sensoft Optical setup Optical setup Ext Illum test Int Ilum test Properties Description Ext Illum test Int Illum test Properties Beam Expander Description Calibration Telescopes Flat spheric
76. essaececececsensaececececseseaaeceeececeeseasseeeeseseneaees 107 8 3 TEST OF TELESCOPE AT PRIME NEWTONIAN FOCUS cccessessssecececeessnececececsesenececececeeseseeeeeseeeneaees 109 8 4 TEST OF SINGLE LENS IN PARALLEL LIGHT USING EXTERNAL ILLUMINATION uses 111 8 5 TEST OF MULTI COMPONENT LENS IN PARALLEL LIGHT USING EXTERNAL ILLUMINATION 112 SiG EASBRS eere M AEN EIN Re EMO 8 7 TEST OF CONCAVE MIRROR scsssscecececsessaececececsesseaececececeessaaeseeececeeseaueceeececseseaaececececseseasaeeeesceeneaaees 8 8 TEST OF FLAT MIRROR SINGLE PASS ccssssscccccecsesssececececeesssaeeeccceceessaececececseseaececececeeseasaeseeeceenenaees 8 9 TEST OF FLAT MIRROR DOUBLE PASS 8 10 TEST OF SINGLE LENS USING A COLLIMATOR AND A FLAT MIRROR INTERNAL ILLUMINATION 119 8 11 TEST OF MULTIPLE COMPONENT LENS USING A COLLIMATOR AND A FLAT MIRROR INTERNAL IEEUMINATION a edi Eee eit enr ed ar RE ve ARE RE voee er Rede e UE ee Ae d erre RS 121 8 12 TEST OF SINGLE LENS IN PARALLEL LIGHT USING A SPHERICAL MIRROR INTERNAL ILLUMINATION 123 8 13 TEST OF MULTI COMPONENT LENS IN PARALLEL LIGHT USING A SPHERICAL MIRROR INTERNAL TELUMINATION sans rentre 125 S TA TEST OF THE HUMAN EYE a ibi o reed eei ne eee ene e eres 127 8 15 TEST OF FLAT MIRROR IN RITCHEY COMMON SETUP trennen trennen 129 8 16 TABEE OF CONFIGURATIONS tete ess tg e ee EE Ee ER ED RA
77. f the SH system itself are removed taking a calibration image of a small high quality spherical mirror instead of the Test spherical mirror This determines the accuracy of the test Input Values for wavefront analysis 115 D esx aperture of test element fl C2 focal length of test element fl focal length of collimator test col Output information Along with the Zernike coefficients the wavefront and optical quality Sensoft gives diagnostics for correcting defocus and spherical aberration which is minimized by shifting the focal plane These corrections can be based on analytical formulae or on a lookup table provided by the user The test can also be used to derive the conic coefficient K from the measured ASA using the above equation Single or double pass Single pass 116 Chapter 8 Optino Puntino test configurations 8 8 Test of flat mirror single pass Setup In the above configuration light is made parallel by the collimating lens C1 and passes through the beam splitter It then illuminates the Test flat mirror and is reflected back into Optino Instrument Optino Beam expander A beam expander can be used to expand or compress the size of the output beam Calibration The aberrations of the SH system itself are removed taking a calibration image of a high quality flat reference mirror instead of the test mirror This determines the accuracy of the test Input Values for wav
78. front sensor Auto Lens Loop QAlign Align El Call 23 2 An image whose filename is FocusM0001 fit is created in the directory that has been specified in the Directories field of the SH Directories folder The image is continuously overwritten and then analyzed The program automatically optimizes the exposure time The stepper motor starts from the current position The software will draw on the SH image a green for converging light or red circle diverging light The diameter of the circle is proportional to the distance from the focal plane The number on top left of the image gives an indication of how far you from the focus 0 corresponds to the correct focus and a standard value for the tolerance is 0 2 The stepper motor is moved to the next position by the number of steps automatically computed by the program and proportional to the distance from the correct focus a new SH image is acquired the exposure time is optimized and the analysis is repeated the measurement satisfies the motorized collimator focus tolerance a beep indicates that Optino is now giving parallel light The green or red circle is filled in with a white disk and the focus loop should be manually stopped by unchecking the MColl box The position of the stepper motor corresponding to the correct focus is showed in the status bar on the bottom of the screen
79. g will appear displaying the suffix automatically given by the program Image name definition Overwrite last image Create new image REF_pinhole0001 Create with new name Enter new name If you want to use a suffix other than the default Ref for your calibration image select Create with new name and define a different string in the Enter new name field By pressing on the OK button the calibration image will be automatically acquired and saved in the directory that has been already specified outdir_results The image is analyzed using an automatic procedure to find out the best cutoff threshold for getting the centroids of the spots You should get an image similar to the one shown below This is the calibration reference image for the SH analysis The reference image analysis represents the first step of the general SH analysis After image analysis the x and y coordinates of the centroids detected in the image will be written to the file ref cen in the directory outdir_results single The graph with the centroids will be displayed on the screen at the end of the analysis This reference image is used for all the subsequent analysis 1 2 6 On line and off line acquisition and analysis of reference SH images There are two ways for changing the current reference image On Line If you press again the Ref button Sensoft will display a dialog asking you if you want to overwrite t
80. gher order Spherical a Default Higher order Coma Higher order Astigmatisrr RE Higher order TriComa Higher order QuadAst Higher order Foil Sj i Polynomials 3D Reconstruction Extra terms selection Annular Zernikes Wavefront e None Standard 2 Surface 1 Extra per group Fringe Zernikes Seidel O0O O Actual Quality AQ definition Tiltonk Tilt and Defocus User selected O In the SH Graphics folder choose the graphs that you wish to see at the end of the analysis Shack Hartmann Directories Zemikes Analysis parameters Utilities Graphics SH analysis Mirror and reference centroids Combined centroids Li EE Profile E Residuals 3D Residuals None xO YO Spot diagram Fj Average loc Wavefront M Actual Quality tilt removed 3D Contour v terms v Terms fitted Click on the Lens button in the dialog bar on the top of the screen to automatically take a SH image of the optical system under test and to do an analysis The image displayed on your screen is also saved in the directory outdir results with the fit extension After analysis several output files are produced with the name of the image being appended to files with different extensions The files will be written in the directory outdir_results single For example analysis of image NP25 will produce the output files NP25 sha
81. has a cooled CCD chip long integration times can be used This is useful when the light source is weak or when a narrow band filter is tested Main features Digital camera Wavelength range 325 1100nm wavelength range Cooled CCD chip 50x50 spots with 300p standard grid 24u pixels Size 24 5 mm x 24 4 mm USB2 connection Cable lengths of up to 500m can be used with repeaters 178 14 1 2 Camera for the IR region 400 1800nm 14 1 2 1 Uncooled Camera 6 This is a Vidicon camera that can be used from 400nm 1800nm It is an analog camera that uses a video converter for converting the signal to digital form Main features Analog camera Comes with video converter for A D conversion Wavelength range 400 1800nm wavelength range 25 4mm Infrared Vidicon chip 30 30 spots with 300p standard grid 14u pixels effective Size 12 7 mm x 9 5 mm Firewire connection Cable lengths of up to 72m can be used with repeaters be run from laptop with a PCMCIA card 179 14 2 Uncooled Standard camera 1 375 1064nm 23x23 spots 14 2 1 Standard digital camera with high quality CMOS sensor This high performance CMOS imaging sensor has an extreme uniform pixel array and an extremely low fixed pattern noise because of its Distributed Pixel Amplifier architecture It is controlled via a Firewire port TEEE1394 The camera can be used in the above range It has a sensitivit
82. he current reference image Image name definition Overwrite last image REF_flat0001 8 Create new image REF_flat0002 Create with new name Optimize exposure time 10 selecting Overwrite last image and then pressing the image will be overwritten and analyzed if Ref0001 is the current reference Ref0001 will be overwritten By selecting Create new image and then pressing OK a new image will be created using the same prefix as the current one but increasing the counter if Ref0001 is the current reference Ref0002 will be created By selecting Create with new name a new image will be created using the Name specified in the Enter new name field when the button is pressed checking the Optimize exposure time box the quick optimization of exposure time QAuto will be done before starting the acquisition of the final reference image By pressing Cancel Sensoft will not proceed Off line An old image can be selected as reference in the SH Directories folder If this image has already been analyzed the output results already exist and Sensoft will ask to use these files for the next analysis If the image has never been analyzed you will need to analyze it To do this you will have to select the auto threshold in the SH Analysis parameters and reference centroid only in SH Utilities then press Analysis the button in the dialog bar Shack Ha
83. heck the collimation of the light beam A green circle shows that the light is converging and a red circle shows that the light is diverging When the test element gives collimated light according to the tolerances specified by pressing the 4 button close to the Coll box in the Dialog bar a white circle will be displayed Tolerances specified by pressing the LC button close to the Coll box in the Dialog bar Tolerances for collimation Tolerance 0 1 10 Specify a value of 0 2 A tighter tolerance may be required in certain cases e g for aspherical elements The image displayed on your screen is also saved in the directory for results specified in the SH Directories page with the name Focus0001 fit The image is continuously overwritten the saved image contains always the last image on the screen If for any reason Sensoft is not able to analyze the image the program will go in Pause mode and a dialog will appear on the bottom right corner of the screen You can restart the analysis by pressing the button OK on this dialog 1 2 9 Recheck the alignment section 1 2 7 1 2 10 Ensure that you are using the correct optical setup and parameters in the Opt page 15 1 2 11 Specify the ellipticity cutoff Sensoft can reject elongated spots that might arise due to spurious effects The recommended ellipticity cutoff is 0 7 Le all spots with an ellipticity higher than this will be rejected The ellipticity of th
84. iagnostics sine een 4 6 3 Coma calibration a e ERR ERE REESE ERES ERECTUS 4 6 4 3rd order spherical aberration SA3 calibration 4 7 INPUT 3 PARAMETERS REQUIRED FOR ANALYSIS cccessessscecececsessaecececececneseaececeesesesssaesececessessaaeeeeecs 47 AI Directories EE 4 72 Zernike polynomials eee deter eee 4 7 3 3D 2D plots of wavefront or optical surface 4 7 4 Threshold 4 7 3 FEllipticity cutoffs ee md e eei Ee e ea e rae en 63 iii 4 756 Use annulus seio EE ont ea et 63 47 7 Combination factor xui trt aei ne te Mint Art te ERR ARI edd 64 47 8 Correlation factor see a e e dete e e re egeat e Ee RR E Fe REI RU 64 4 7 9 0utput UNS ns i oO OG DEDI UU MD DE Mee a re e EM RU 64 4 7 9 1 Spot diagram distribution of residuals Encircled Energy profile 64 4 102 WayvefrOont n ee Rte p ee OO EE ERE e Ies 64 4 8 NOTES ON THE INPUT PARAMETERS eee 65 d o See et CY ERAS 65 4 6 2 Why focal lengths are used for flat ss 65 4 9 MOTORIZED BEAM EXPANDER OF SPOT OPTICS nee 66 4 9 1 Using Optino with motorized beam expander compressor ss 66 4 9 2 MGINGAVGNIG BES ovis sine ee nt Ce el nie 66 4 10 COMPUTATION OF THE NORMALIZED RADIUS en eene treten entren trennen 68 4 10 1 Test bea
85. ick the Live button to start the exposure and check that the camera is functioning by covering and uncovering it with a paper or your hand If you can see an image with some spots on the screen experiment with the QAuto feature of the camera exposure otherwise use the Auto By checking this button the exposure time changes automatically to give you optimum exposure This is required to get a good S N ratio without saturating overexposing the camera The exposure will increase decrease until the background of the exposure time box becomes green or yellow The color red like in figure below indicates that there is too much of light a blue color indicates too little and green yellow indicates OK Uncheck the Live box C Sensoft Shack Hartmann wavefront sensor software for Optino File Edit Toolbars Image arithmetic CCD Grid Motor Simulation Utilities Window Help ESSE cour OD Loop asin Calin call FO MBEx Adjust the tilt of the flat mirror to center the SH image on the camera The alignment of the SH camera is important the SH spots should be aligned along the rows and columns to a precision of about 1 pixel Alignment of the SH camera can be done by adjusting two screws at the top and left or bottom in some eatlier models using Allen keys See section 1 2 3 1 2 Optino details of setup and use n this section the basic steps and co
86. id while for the image of the optical system under test their positions are on an irregular grid due to the aberrations of the optical surface see section 6 1 95 Chapter 6 Analysis of results 1 the shapes and intensity of the spots 6 5 2 Distribution of intensity of the spots over the image This graph gives the total intensity of each of the spots displayed in the centroid graph The variation of intensity is due either to the illumination optical setup or to defects in a certain region of the optical surface under test Ideally the distribution of intensity should be uniform over all the spots This is mostly true for the reference image For the image of the optical system under test the distribution is not uniform due to variation in the reflectivity of the surface If the same pronounced effect is present in the same area in the distribution of intensity for both reference and lapping plate image it is possible that the calibration light source is not giving a uniform illumination e g if the fiber is not inserted correctly If the non uniformity condition in the image of the lapping plate persists despite these precautions ot it is not present in the reference image it means that there is a real variation in reflectivity over the area of the lapping plate being tested We recommend that you use the normalized 3D and contour plots of the intensity distribution In these plots the non uniformity in the reference image has bee
87. image with the Open command in the file menu By clicking on the button you will obtain a duplicate of the image Click on the D button and draw with the mouse a containing the bad spot in the image on the left of the screen If you click the ae buttons you will draw a citcle You ate given the choice to discard the rectangle circle and in this case you have to restart the procedure from the previous point or to accept the rectangle circle and in this case the 8 corresponding spot will disappear from the duplicated image on the right Using the buttons the spots inside the rectangle circle will disappear using the button the spots outside the circle will disappear Repeat the procedure for all the bad spots in the image and then close the procedure by clicking on the S button You will be prompted for overwriting the original frame You can also save the modified frame with a different name using the Save As command on the File menu An example of the display during the procedure is given in the figure below 79 80 4 14 Hardware 4 14 1 Instrument Optino or Puntino The appropriate collimator C2 see Section 4 15 on Choosing the right collimator 4 14 2 Light source for illuminating the test element For illuminating the optical element 25 23mm beam ECM60 58 5mm beam 120 120mm beam All ECMs use diffraction limited collimators and give a maximum reference
88. in Coude focus mainly astronomical telescopes analytical formulae can be used for computing the calibration The input required is the conic coefficient of the secondary mirror K and the normalized back focal distance p See Section 4 6 on Input parametets 61 4 7 Input 3 Parameters required for analysis 4 7 1 Directories Where The directory for storing the images and output files is specified in SH Directories 4 7 2 Zernike polynomials Sensoft allows you to select one of the following Zernike polynomials to fit to the data Annular Fringe Standard In addition pure Seidel polynomials can also be fit to the data Please see separate chapter on Zernike polynomials and Sensoft Where The selection is done in SH Zernikes 4 7 3 3D 2D plots of wavefront or optical surface Sensoft can compute the wavefront or the surface The difference between the plot of the wavefront and the surface lies in the following points The sign convention is different The wavefront is positive if it is retarded with respect to the spherical wavefront This is counter to the normal sign convention For the surface the convention is the standard one it is positive if it is advanced with respect to the spherical surface For reflection from a mirror the wavefront is doubled This is taken into account by Sensoft Whenever a test for a lens is done in double pass the wavefront aberration is doubled Sensoft takes this i
89. ing the camera with hubs for long cable lengths USING SENSOBT UPTIN O er A ctu CL Re AN etre tese NE LEER CHAPTER 4 TESTING WITH OPTINO REFERENCE GUIDE eere 45 4 1 THE SHACK HARTMANN METHOD eceeeeeten e e e ememenennnnnnn ener nnns ise ese ese ese ese 46 4 1 1 General 46 42 TERMINOLOGY ei or err EE OE PIE CEU et pees CEU EE POE ERE NEUE CENTER RE ERE QE ET TERN UE 47 4 3 THE OPTICAL TEST CONFIGURATIONS cscsssescsssescssesesesecesesseseesseseesssesesseessssesesesseseassessuessenees 48 4 3 1 Converging lens in external illumination single pass 48 4 3 1 1 Light source for illuminating the test element 48 43 12 Calibration Of Open eire rti Etre Ee lere rH e obe rte een esta 48 4 3 1 3 Maximum diameter that can be tested ss 49 4 3 2 Converging lens in internal illumination double pass spherical mirror 49 4 3 2 1 Light source for illuminating the test element 4 3 2 2 Calibration of Optino 4 3 2 3 Maximum size that can be tested 4 3 3 Converging lens internal illumination with flat mirror double pass 51 4 3 3 1 Light source for illuminating the test element 4 3 3 2 Calibration Of ertet ether cepe EN IEEE en ent 4 3 3 3 Maximum size that can be tested sise 4 3 4 Flat surfaces mirrors internal illumination single
90. ion light source and Optino 6 3 Choice of plots to display The first step of the analysis of the Shack Hartmann image consists in computing the center of gravity of the spots in the image At the end of this analysis Sensoft creates a file with extension cen that contains information about the position of the spots their ellipticity intensity Signal Noise called S N ratio In Sensoft you can select among these different graphs in the SH Utilities page Shack Hartmann Directories Zemikes Analysis parameters Utilities Graphics D D RN Centroids Plotff centroids Reference centroids only O Reference Mirror Relax controls on reference threshold Mirror centroids only vs spot On pupil Relax controls on mirror threshold Ellipticity F F Skip reference centroiding Intensity L all Start from combined spots S N ratio 30 and contour plots of centroids Ellipticity 3D Ellipticity contour Intensity 3D Intensity contour S S IS 1 C Normalized Intensity 3D ormalized Intensity contour Note The plots for the reference image are shown only if the Reference box is checked and that for the lens image only if the Lens box is checked 94 Chapter 6 Analysis of results 1 the shapes and intensity of the spots 6 4 On Line and off line display of the plots The graphs selected in SH Utilities are automatically displayed in one of the two fol
91. ired Chapter 1 Optino Pro and EE Initial setup and use Diverging or converging light can be obtained to illuminate the Test optical element 10 1 3 Other features It can provide beam diameter of up to 23mm ECM25 or 58 5mm ECM60 When it is used for calibrating Optino directly the beam diameter depends on the camera model For the standard camera that comes with Optino and OMI the beam size is of 6 6mm 10 2 Using ECM 10 2 1 Preliminaries Notes Square brackets refer to commands of Sensoft When the stepper motor is connected to the power supply for the first time it will go to the Home 0 steps position 10 2 2 The initial steps Connect the motor of ECM to any wall mounted stabilized 12V 500mA power supply This will make the stepper motor go to Home position 0 steps The maximum number of steps is 1700 each step corresponding to 21u giving a total movement of 35 7mm Connect the serial port of ECM to the PC using 9 pin serial cable comes with the pinhole already mounted inside the holder see Chapter 1 Optino Pro and EE Initial setup and use The adapter for the fiber is also mounted inside the pinhole mounting Take this adapter out of the mounting by unscrewing the setscrew Mount it over one end of the fiber optic light guide Connect the other end of the fiber to a fiber optic light source or to a luminous LED You ate now ready to use ECM 10 2 3 Getting parallel light with
92. ired for an accurate computation of the centroid parameters Image REF0001 2003 12 11 11 15 19 Y pixels S N 58 0 500 76 9 9 o rs 0000 0 0 0 0 0 0 000000 0 0 0 0 0 0 000000 0 0 0 0 0 eee 0 0000 00 0 0 0 0 0 0 0 0e e 9 e 9 9 e 0 0 0 0 0 0 0 0 0 0 E 0 0 0 0 0 0 0 e 6 6 6 0 0 0 0 0 0 0 0 ee 00 0 6 6 0000 0 0 0 0 0 0 0 0 0 0 e 000 0 0 ee e e e 0 0 0 0 0 0 0 e e o o o o 9 00 0 0 0e 260 e o o 0 0 0 0 0 E E 000000 0 0 0 0999 9 Average 0e Ellipticity 0 079 0 063 Flux spot 1603 367 counts 2 OO 9 O S e Flux pixel 18 3 counts Signal noise 117 17 60 0 0 0 0 19 00 0 e 0 0 0 000 0 0 100 200 300 400 500 X pixels Plot of signal to noise distribution over the i
93. its equivalent focal ratio is 10 choose a collimator of focal ratio f 10 71 C75 The number of spots will be reduced by a factor of 10 10 71 or by 0 93 and one would get 21 spots instead of 22 Table 10 Name Diameter Focal F ratio mm length mm C35 25 35 5 C40 25 40 5 71 C45 25 45 6 42 C50 25 50 7 14 C60 25 60 8 57 C75 25 75 10 71 C85 25 85 12 14 C100 25 100 14 28 C125 25 125 17 86 C150 25 150 21 45 C175 25 175 25 00 C200 25 200 28 57 C225 25 225 32 14 C250 25 250 35 71 C275 25 275 39 29 C300 25 300 42 86 C400 25 400 57 14 C500 25 500 71 43 C850 76 56 849 96 121 42 C1524 102 31 1524 73 217 82 C1887 128 02 1887 58 269 65 1 2 3 4 5 6 7 8 83 Chapter 5 On line adjustment of optical systems 84 5 1 Introduction adjusting a complex optical system Optino can be used for the on line adjustment of complex optical systems The software Sensoft has a powerful set of features that allows you to Align the system using the on line measurement of coma and astigmatism Find the correct focal plane by measuring defocus and spherical aberration 5 2 Preparing the system for the test Itis extremely important that the test optical element and the illumination source are setup and mounted correctly otherwise wrong results may be obtained This 1s especially true for fast systems low F ot high NA Please contact us for your requirements for fast systems In this section we discuss the mechanical setup
94. ke coefficient the wavefront and optical quality of the flat mirror The conic coefficient of the test mirror can also be computed the spherical aberration of a mirror at its center of curvature is given by 3 r ASA K 2R Here ASA is the angular spherical aberration diameter of image at best focus in radians K the conic coefficient of the mirror r the ray height on the mirror and R the radius of curvature Spherical mirrors have zero ASA K 0 while parabolic 1 and hyperbolic lt 1 mirrors have large positive spherical aberration However Sensoft is capable of testing mirrors with hundreds of wavelengths of aberrations Single or double pass Double pass 130 8 16 Table of configurations Table 11 Double ae Reference image Limit on aperture Defoc SA Coma External illumination 6 Cassegrain Telescope Newtonian Telescope Single lens in parallel light Multiple lens in parallel light Single lens with pinhole Multiple lens with pinhole At focus of C2 At focus of C2 At focus of C2 At focus of C2 Parallel light Parallel light None F Tel F col None F mir FH col None None None None 7 Laser Parallel light 6 6mm Internal illumination 0 Concave mirror at R C Flat mirror single pass Flat mirror double pass Filter wedge Single lens with collimator Multiple lens with collimator Single lens in parallel light wi
95. kground color depends from the tolerances defined in the loop param dialog that is displayed by clicking on the EC button close to the Loop box Standard Zernike coefficients Aber mn Cx nm Cy nm Def 02 Tilt 11 1 0 7 7 13 1 0 0 3 SA3 0 4 Ast3 2 17 0 4 TCom 3 3 14 0 2 QAst 44 14 0 5 Coma5 15 0 3 0 2 SAS 0 6 Err Error in the estimation of C computed from the least squares fit Err ang Error in the estimation of the angle Error estimation can be obtained from the printout of the sha file contained in the directory where the SH images have been saved 4 12 5 Diameter of image in focal plane due to individual aberrations The Zernike aberration coefficients refer to the wavefront The effect of the aberrations is to spread out the image in the focal plane Sensoft gives the size of the image containing 100 Encircled Energy in the focal plane corresponding to each of the first 7 aberrations as if only that aberration were present This helps understand the importance of each individual aberration 76 The units can be in arcsec used in astronomy or microns Note The spot diagram also gives the same information if the particular aberration is not fit to the data and the effect of the rest of the aberrations is subtracted out 4 12 6 Graphs Sensoft can be asked to plot a number of graphs see Help 4 12 6 1 Manipulating graphs The graphs can be manipulated by using the right
96. lay 2D section of the wavefront at 0 deg and 90 deg and at 45 deg and 135 deg Display X and Y coordinate labels in spots or mm units User can select the same scale in waves ot nm units for all of the 3D and contour plots 4 12 6 5 Printing graphs and tables Click on the graph that you wish to print adjusting its size as desired Use the Print option in the File menu Similarly the table obtained after the analysis can also be printed without the possibility of adjusting its size In both cases the Print Preview command can be used prior to print out 4 13 Rejection of bad spots in a SH image his procedure is part of the advanced image analysis and is available only in the SensoftOptino Pro and EE version Bad spots can be due to scattered light or to optical zones on the optical element under test They are identified in the SH image because they can have a diameter slightly larger than the neighborhood spots ot because they are merged with another spot or they are completely out of the regular grid of spots normally resulting in the SH image An example of a frame containing spots that can make difficult the SH analysis is in the figure below 78 PF ee NN L LI LO Ld bd ew ET LI LM The image bar on the top of the screen contains three buttons that can be used to identify and reject the bad spots 8 5 757 4 9 The procedure is as follows Open a SH
97. lerances specified in the dialog that is opened by pressing on the EU button close to the Align box a beep indicates that the alignment has been obtained and the green circle is filled with a white one Used for on line collimation of the optical system under test Does not require any reference image The software gives the indication of the movement inside or outside to collimate the beam from the optical system under test When the collimation is inside the tolerances specified in the dialog that is opened by pressing on the EC button close to the Coll box a beep indicates that the light is parallel At this point the loop is automatically stopped MColl Optino Pro and EE versions only Used for obtaining collimated parallel light with the motorized collimator pinhole light from the internal light source of Optino Does not require any reference image The software analyzes the beam coming from the optical system under test optimizing the exposure time and move the motor inside or outside inside Optino to obtain collimated light When the collimation is inside the tolerances a beep is signaling that the correct collimation has been reached At this point the on line loop is automatically stopped 27 MBexp Optino Pro and EE versions only when system is shipped with beam expander Used for obtaining collimated parallel light with the motorized lens inside the beam expander Does not require any reference image Same as for
98. lowing ways On Line at the end of the analysis when the Ref Test Lens or Analysis buttons are clicked Off line by opening the centroid file file with cen extension of am image that has been already analyzed from the File Menu and clicking the Plot button in the dialog bar Sensoft Shack Hartmann wavefront sensor software for Optino oy Edit View Image arithmetic Motor Simulation Utilities Window Open SH result file cof us T 1000 tive Rer Mest Mi Loop Open Image file tif U Pv Ei ACP tal x B Close Centroids Em Close all Export graphic Frame DEFECT RGP43 2003 09 01 11 47 30 Load optical configuration Y pixels Save optical configuration Print Ctrl P Print Preview Print Setup Rename file Rename set of files SH results cof Image files fits Image files tif Centroid files cen Y Y Y v Exit 200 400 Average X pixels Ellipticity 0 096 0 056 Flux spot 1382 454 counts Flux pixel 23 5 counts Signal noise 108 20 6 5 Examples of the various plots 6 5 1 Positions of the centroids This graph gives the computed position of the center of gravity of the spots in the image An example is given below for a reference image For the absolute reference image these points have a regular distribution on a gr
99. lt 20p Do the SH analysis 148 9 9 Computation of the normalized radius As explained below the beam from the beam expander can lead to under or overfilling of the optical element being tested Sensoft takes this into account See Chapter 4 Testing with Optino reference guide for a detailed discussion of this problem 9 9 1 The test beam is larger than the aperture of the optical element and is vignetted D lt D input no BE D test lt with BE Expanded Separation beam P D test Motorized lens Fixed lens L2 149 9 9 2 The beam from Optino or the BE does not fill the optical element completely Ds gt D no BE test L D gt Dpp with BE test Expanded beam Separation Input beam D input Fixed lens L2 Sensoft takes this into account Also see section on the normalized radius 150 Chapter 10 The external motorized calibration unit ECM 151 10 1 The external motorized calibration unit ECM 10 1 1 Principle of the ECM It consists of a motorized high quality diffraction limited at 632nm collimator lens that collimates the light from a pinhole illuminated by a fiber The light can be used for calibrating Optino or for testing any optical element 10 1 2 Main Advantages The motorized lens ensures that parallel light is obtained easily A filter can be used with the fiber optic light source Thus the test can be done at any wavelength des
100. m Name BEpos Mag Comp Sep 12 Dege DBE ES uc 9 5 ut 6 6 1 BE2501 4or5 1 5 0 66 118 7 50 75 0 12 8 9 9 BE2502 20r3 2 0 0 50 84 0 30 60 0 17 5 13 2 Ee 5 seme 22 388 7 2504 3 3 0 3 121 5 30 100 0 28 0 21 8 Notes Mag Magnification M fi 2 1 Vo 1 fl2 Comp Compression m7 Sep Separation of the lenses L1 and L2 bfl1 bfl2 where bfll and bfl2 are the back focal lengths of the lenses Also see section on Beam compressor 138 9 3 3 BE60 The lens positions and the magnifications Table 13 BE pos Mag Hole Includes BE 25 see table for BE25 above 5 BE6001 11 4 2 0 24 85 3549 357 6 BE6002 11 4 7 0 21 75 3549 400 7 BE6003 10 5 9 0 17 60 3549 50 2 8 BE6004 9 7 1 0 14 j 50 354 9 BE6005 8 8 9 0 11 380 40 354 9 Notes Mag Magnification fl2 ful Vor gig Comp Compression AUA Sep Separation of the lenses L1 and L2 bfl1 bfl2 where bfl1 and bfl2 are the back focal lengths of the lenses Boxes in red indicate that the output beam is truncated to 58 5m Also see section on Beam compressor 139 9 3 4 BE25 and BE60 summary of magnifications available 9 3 4 1 Input beam diameters 9mm and 6 9mm The following graphs display graphically the output beam diameter for different beam expander positions The output is given for input beam diameters of 6 9mm and 9mm Beam Expander output BE25 35 30 25 20 9mm Fa 15 Fa in
101. m overfilling and under filling the test element 68 4 10 2 Normalized radius no vignetting 68 4 10 3 The test beam is larger than the aperture of the optical element and is vignetted 69 4 10 4 The beam from Optino or the BE does not fill the optical element completely 70 4 10 5 The effect of spot sampling on normalized radius ss 71 4 11 OFF LINE AND ON LINE ANALYSIS een enr eR ENEE E nete tenerent entree 73 4 IEIDOff line Qn lyvsisi s coe tend eed tee oS eee eee RR Deed ete tee te bt ett 73 4 11 2 On line real time analysis siennes 73 4 11 3 On line alignment of multi component systems ss 74 4 12 OUTPUT FROM SENSOET edere bester ete pe debere rhe ER D err epe Re Rea bere eae 75 4 12 1 Basic introduction to how Sensoft works ss 75 4 12 2 N0me definitions ite eer o nd oS ede Re ER Er ori Te OR eed 4 19 2 T AQ Actual quality 2 ede teer er etes ete 4 12 2 2 RQ Residual quality 4 12 2 3 PQ Potential quality ALL ZS WhidtiQto l00K JOT s iu ee li n E e cree E e natures 412 4 Zernike COeffiClentss ui t eet e ee Er Dee E ER eR das ERR IHE 4 12 5 Diameter of image in focal plane due to individual aberrations esses d 12 6 Graphs ee eod ke eot et ere entente ed M re Ee MR DIE EE S ECRIRE he 4 12 6 1 Manipulating graphs sise 4 1262 ZOOMING graphs RC NEAR TO 4 12 6 3 Exp
102. m size of 400mm 53 Chapter 4 Testing with Optino reference guide In the Ritchey Common setup a larger mirror can be tested Please ask us 4 3 5 Flat surfaces filters in transmission single or double pass Optical elements like filters optical windows and wedges can be tested by inserting them in the parallel optical beam The test can be done in internal illumination like for the testing of optical flats or external illumination mode 4 3 5 1 Light source for illuminating the test element The internal light source of Optino is used for the test 54 Chapter 4 Testing with Optino reference guide 4 3 5 2 Calibration of Optino The reference calibration image is taken without the filter Note that a high quality mirror is not required for getting the reference image as the aberrations of the reference mirror used cancel out because the same mirror is used to get the Test image 4 3 5 3 Maximum size that can be tested Using a beam expander a maximum of 400mm beam can be tested 4 3 6 Lasers single pass Like for the test in parallel light The test is in single pass 55 4 4 Repeatability and accuracy of the SH test 4 4 1 The importance of calibration It is important to distinguish between the repeatability sometimes called precision and accuracy of the results obtained with a SH tester like Optino All good test systems have a high degree of repeatability or precision but the absolute acc
103. mage of a reference The spots with higher S N are displayed with dots of increasing diameter A S N ratio of at least 100 is required for obtaining good results If you have a low S N ratio increase the exposure time up to about 50ms Alternatively increase the light intensity of the fiber optic light source 97 intensity of the spots the shapes and i f results 1 is O Analys Chapter 6 Y pixels 500 400 300 200 100 500 400 300 200 100 X pixels Average 0 079 0 063 Ellipticity Flux spot 367 counts 1603 3 counts 17 18 117 Flux pixel Signal noise Plot of centroids for the reference image shown on top As expected the average value and gt 100 10 1S per spot rati 15 The Signal No ipticity are sma the rms value of the ell 98 f the spots intensity the shapes and f results 1 is O Analys Chapter 6 Intensity Y pixels 544 913 500 1283 1652 2022 400 300 200 Average 0 079 0 063 1603 Ellipticity Flux spot 3 counts 367 counts 17 18 117 Flux pixel Signal noise 100 500 400 300 200 100 X pixels 1 500 400 300 200 Average 0 079 0 063 1603 Ellipticity Flux spot 367 counts 3 counts 17 18 117
104. mirror 49 123 single lens using a collimator and a flat mirror 51 119 test instrument 81 107 109 111 112 114 115 117 118 119 121 123 125 127 129 the internal illumination system 33 Optino test configuration external illumination multiple component converging lens in external illumination single pass 112 single lens in external illumination single pass 48 111 lasers 55 58 114 P Potential Quality PQ 22 103 Q Quadratic astigmatism 14 22 75 168 169 170 171 172 R Real time analysis 73 References 164 173 174 Rejection of spots 78 Residual Quality 22 103 S Schroeder D J 174 Seidel polynomials expressions for first 8 terms 62 164 165 171 Sensoft off line analysis 22 73 on line analysis 73 real time analysis 73 real time analysis of multi component optical system 74 using Excel 103 Zernike polynomials used 162 Sensoft Optino installation of software 42 installation of the Firewire uncooled camera 43 Shack Hartmann analysis accuracy 56 Actual Quality AQ 17 22 103 diameter of image due to individual aberrations 76 graphs 77 parameters for centroiding ellipticity 63 93 threshold 21 62 Potential Quality PQ 22 103 precision 56 rejection of spots 78 repeatibility 56 Residual Quality 22 103 spot diagram 64 wavefront 17 56 64 132 which test to use single or double pas
105. mouse button which presents a number of options ombined Spots Simulation 2D Chart Control Properties Control Axes ChartGroups CharStyles Titles Legend ChartArea PlotArea ChartLabels View3D Markers General Depth a Elevation Rotation Shading Calor gt e e 0 2 e n al me ese 4 12 6 2 Zooming graphs To zoom a graph use the mouse Keeping the Shift key pressed mark the area to be zoomed using the left mouse key To return to the original graph press 4 12 6 3 Exporting graphs in J or BITMAP format 2D and 3D graphs can be saved in JPEG or BITMAP format using the Export graph function from the File menu and selecting among the available format 77 4 12 6 4 The graphic toolbar Individual plots can be modified by using the buttons of the toolbar top right of the window Each button corresponds to a different operation that can be performed on the plot Table 9 8 Show Hide a grid on the view to help identifying x values default FALSE Show Hide the legend on the view default TRUE LE Convert the view from to color to grayscale and back default color Copy the view to the clipboard in enhanced metafile format Change the size of the vectors of the residuals EB Change the number of contour levels on the wavefront Convert the wavefront scale into waves units default lambda is 632nm Disp
106. n a lookup table provided by the user for any optical element in the system Single or double pass Double pass 126 8 14 Test of the human eye ToSH system Cornea n LI _ Light source with pinhole Setup For testing the eye the basic configuration is the same as that for the test of a test of single lens in parallel light internal illumination Note that in this situation the eye acts as the optical element being tested and the collimator Thus the focal length of the collimator and optical element to be entered in the Optics section are the same Furthermore if the diameter of the returning parallel beam from the eye is changed using additional optics the factor called the reduction factor by which the beam is reduced or enlarged should be entered in the Optics section The value of reduction factor is 1 for no change in beam diameter less than 1 for a reduced beam and more than 1 for an enlarged beam Instrument Optino Calibration The aberrations of the SH system are removed by taking a calibration CCD image with a good quality flat mirror in parallel light before it falls on the lens L Input Values for wavefront analysis Diya input diameter of beam from Optino Ds diameter of test element fles focal length of eye focal length of collimator 2 focal length of eye Output information Sensoft gives the Zernike coefficient the wavefront and optical quality of the
107. n corrected using software by normalization thus the variation that you see is due to the lapping plate only The average values for the ellipticity intensity and the S N ratio are shown in the graphs in the following pages with their respective standard deviation these values give already an indication of the quality of the image A low value for the ellipticity amp indicates that the spots are regular and rounded A reasonable value of 6 for the intensity means that there is little variation over the image A high S N ratio 100 means that the centroid intensity is sufficient to compute the various parameters of the spots accurately 6 5 3 Distribution of ellipticity e of the spots over the image This graph gives the ellipticity of each spot displayed in the centroid graph As mentioned earlier some of spots may be elongated due to the irregularity of the surface being tested However a low intensity of the spots can also cause elongation of the spots Thus if it is found that the S N ratio of the spot is high enough 7 50 then the elongation of the spot is due to an irregular surface 96 Chapter 6 Analysis of results 1 the shapes and intensity of the spots 6 5 4 Distribution of Signal to Noise S N ratio of the spots overthe image See the discussion for the distribution of the intensity above The Signal to Noise ratio takes into account the various sources of noise in the camera A S N ratio of gt 100 is requ
108. n your screen will show the same circles as for the Align procedure The image is saved as Loop0001 fit in the directory selected for storing output results outdir results in SH Directories The image is continuously overwritten thus the image file always contains the last image displayed on the screen If for any reason Sensoft cannot analyze the image the loop is put in a Pause mode and a dialog appears on the bottom right corner of the screen You can continue the analysis by pressing the OK button on this dialog The output results are stored in the subdirectory outdir results single Note The first analysis is done using the automatic threshold the next analysis is done keeping the same Threshold unless Sensoft is in Pause mode When the Pause mode is reset the analysis restarts using the automatic threshold The coefficients computed in the loop are sent automatically to an external computer in the OptinoEE version using the serial port for communication 21 1 2 15 Off line analysis The Shack Hartmann analysis on an image can be done on line as described in section 1 2 12 and 1 2 13 or off line as described below In the SH Directories section select the Lens and if desired the reference images Shack Hartmann Directories Zemikes Analysis parameters Utilities Graphics Select directory for results CAsensotiTDK Select Reference image _ C sensot iTDK ref0001 fit Sele
109. ncepts of the analysis are presented For more details on any topic see Help 1 2 1 Operate the stepper motor to get parallel light OptinoPro and OptinoEE come with a motorized collimator for obtaining parallel light see section 1 3 The stepper motor controls the movement of the collimator When Sensoft is launched the software automatically searches for the COM port to which the serial cable has been connected If Sensoft is not able to establish any serial communication check the serial cable connection and that you are using the proper power supply 12Volt 500MA inner polarity positive After you connect the power supply to Optino wait for a while before restarting Sensoft If you have the version with the internal collimator only the motor will be initialized to the last position stored in the registers of the program In case you have the version with beam expander the following dialog will be displayed Motors connection Sensoft has found 1 motar s connected Collimator is connected to 8 COM3 v Set as current Beam expander is connected to O COM3 C Setas current e Choose the motor connected to the COM port e The motor will be initialized to the last position stored in the registers of the program for the selected motor e When the motor initialization terminates without errors the button correspondent to the selected motor on the Motor toolbar will turn to green color and the status will turn t
110. ne For coarse rotation of camera 3x120 degrees 38 Chapter 3 Sensoft Optino Software installation 39 3 1 System requirements 3 1 2 System requirements for PC Windows XP 512 MB RAM A video card with 32 bit True color graphics capability and 64MB or more of video memoty About 120Mb of hard disk space to store the dark calibration images for the uncooled cameta The uncooled Firewire camera requires a 6 pin to 6 pin 2meter or longer 1394 cable and a 1394 Open Host Controller Interface D HCD or Firewire card to be inserted in the PCI bus of the PC An external 12V 500mA DC power supply for the motorized collimator Office XP or later versions to open the Excel file created during the Shack Hartmann analysis 3 1 3 Additional requirements for laptops With the uncooled camera a 1394 OHCI CardBus card installed in a PCMCIA slot or a built in 1394 port An external 12V 500mA DC power supply 40 3 2 Camera settings 3 2 1 Camera for getting Shack Hartmann images Optino can be used either with an uncooled digital Firewire camera or a Peltier cooled camera 3 2 1 1 Uncooled camera The default SH camera for Sensoft Optino is an IEEE 1394 Firewire based Imaging module For Optino shipped before July 2005 the camera has 1280x1024x7 5u pixels For Optino shipped after July 2005 the camera has 1280 1024 6 7 pixels A total cable length of 72m can be used with repeaters and 4 5m cables An optional PCMCIA card can
111. ngs terminated by the carriage return lt CR gt character Upper or lowercase characters can be used in the composition of the strings The commands can be divided into 2 groups operative and inquiry commands The operative commands change the status of the motor while the inquiry commands check the status of the motor without producing any changes A convenient program to use is Hyperterminal 159 11 2 Operative commands Table 18 returned information is returned X W Move to absolute position a a is in number of steps no information is returned p Inquiry command Used after any of the above commands returns the position of the motor LO Switch off the light source no information is returned Switch on the light source no information is returned Inquiry command Returns the status of the motor light The operative commands change the status of the motor without sending back any reply Hx Da a LO L1 The status of the motor after execution of the command is checked by sending an inquiry of the position W if the position is different from the one requested the inquiry for the status U is sent For on off the light source only the inquiry for the status is requested using U 160 11 3 Inquiry commands Table 19 Request current position the current position is returned Request current firmware version the current firmware version is returned U Status reques
112. nsoft Optino CDROM to complete the installation of the files required for the dongle key The SDI EXE executable will open the Smartkey Driver Installation Folder shown in the figure below Click on the Install button both in the Usb and in the Gss page If the installation is correct the Active box in the page will be checked at the end of the procedure Smartkey Driver Installation Parallel Usb In this Panel you can install and uninstalll the SmartKey Usb Driver Install or Update the SmartKey Usb Driver Uninstall Uninstall the SmartKey Usb Driver Remove with force the SmartKey Usb Driver A Remove rebootis always required Use this command only to recover from a wrong installation Status M Active Version 2 0 0 0 Refresh 42 Restart the system 3 3 3 Installing the SBIG SH CCD under Windows 2000 XP If you use the SBIG CCD please refer to the manufacturer s Operating manual Section 1 2 Installing the USB Drivers for the First Time 3 3 4 Installing the Firewire uncooled camera for the first time If you already installed an old version of Sensoft Optino you should go to the Upgrading the camera driver section 3 3 4 1 Installing the Firewire PCI card on your PC down the power of your PC Install the PCI card The OHCI card provides the PCI to 1394 interface between the host computer and the camera module Switch on the computer Window will automatically detect the OHCI card and
113. nsoft is the diagnostics it gives you the indications both direction and magnitude for correcting Defocus wrong focal plane due to misalignment tilt and decentering of the components of a multi element Optical system Spherical aberration due to the wrong spacing between the elements or use of wrong focal assuming that their shapes are correct The following table gives the input required Table 5 No Calibration of coma and SA3 correction based on ray tracing or empirical calibration Rate of change of coma with decentering of any optical mm mm element Rate of change of coma with tilt of any optical element mm radian Rate of change of spherical aberration with change of spacing mm mm Astronomical telescopes at Cassegrain Coude focus calibration computed from analytical formulae B Normalized back focal distance from vertex of primary dimensionless mirror to telescope focus in units of focal length of primary mirror symbol K Conic coefficient of secondary mirror dimensionless 4 6 2 How Sensoft computes the diagnostics Sensoft measures the coma and spherical aberration and based on the calibration provided by the user or for astronomical telescopes based on analytical formulae indicates how much and in which direction one of the elements specified by the user must be moved to correct for misalignment and wrong spacing of the elements 59 4 6 3 Coma calibration The user should s
114. nt e RUE eR ar edes riens ann 14 3 COOLED CAMERA 2 325 1100NM 30X30 SPOTS SMALL PIXELS SLOWER READ OUT 181 14 3 1 Cooled digital camera with CCD sensor 181 44 3 2 Characteristics i stet ose den e o n dee a D 181 14 323 QuantumzeffiCleney 1 ise e RR e EE RE E dre RU RD NER DH TH rd 181 14 4 COOLED CAMERA 3 350 1100NM 30X30 SPOTS us 182 14 4 1 Cooled digital camera with CCD sensor een 182 T442 C haracteristiCs ioo dee eee etes eoa pede eei rm ini eeu eee ees Ue ni 182 PES ESO TANI MET 182 vi 14 5 COOLED CAMERA 4 325 1100NM 50X50 SPOTS eee 183 14 5 1 Large format cooled digital camera with CCD sensor ss 183 14 5 2 GharacteFistiCs e RE 183 14 5 3 Quanium effiClen6y E ne ent 183 14 6 COOLED CAMERA 5 325 1 1OONM 70X70 SPOTS ess 184 14 6 1 Large format cooled digital camera with CCD sensor ss 184 14 6 2 Characteristis RERO ET 164 14 6 3Quanium effiClenCy ia ades a ret RR e E EVA e ORE RUE EUR a 184 14 7 UNCOOLED CAMERA 6 400 1800NM VIDICON ANALOG CAMERA MAXIMUM SPOT SAMPLING 185 Vidi on IR camera RE 165 14 2 Ch aracteFisties eese oae vo reos eset nn nn nn nn Ve vx a Yee E Ee oae eee eroe nent TUE UE cu Feu
115. nto account mirror the test can be done in double pass like the Ritchey Common test In this case the wavefront is quadrupled Again Sensoft takes this into account Where The user can select to compute wavefront or surface in SH Zernikes and the type of plot to see wavefront or surface in SH Graphics 4 7 4 Threshold An important factor for finding the centroids is the threshold This determines the level over which pixels are included as part of the spot Sensoft uses a complex criterion for this and does it automatically The user can override the automatic threshold computation if required Typical value For good quality images a value of 0 05 to 0 10 is normally found by the software Values up to 0 3 can be used in certain rare cases 62 Where The selection is done in SH Analysis Parameters The value of the threshold can cause small differences of the order of few nm in the values computed by Sensoft A higher threshold compared to the one computed by Sensoft automatically can be used to remove elongated or bad spots 4 7 5 Ellipticity cutoff There are situations where the surface under test can give elliptical spots e g turned down edge or some stray light gives spurious spots These can be removed by specifying an ellipticity parameter defined as 1 b A where aand bare the semi major and semi minor axes of the spot A round spot hase 0 Default value F
116. o If the motor initialization terminates with errors the button correspondent to the selected motor will remain red and the status will remain Off The figures below display the different status Int Collim Int Collim x Int Collim un Ouen Optino with internal Optino with internal Optino with internal collimator only collimator only collimator and beam no motor connection motor connection expander found found motor connection found and activated for internal collimator The motor toolbar can be used conveniently to operate the motor Sensoft keeps the last position reached by the motor in memory When you restart Sensoft the motor automatically moves to the last recorded position Collimator x Home zero position Move to end Move to last collimation position Focus 1350 Collimation position Editable Select pre calibrated collimation position Precalibrated position Editable Move motor forwards Move motor backwards No of steps for movement Editable Current 1350 Current position 1 2 2 Setup the cameras Go to the first page of the WFS property sheet and select the camera setup If you have a cooled camera A dialog bar will appear o the display when you launch Sensoft You can control the CCD camera from the dialog connect disconnect resolution CCD control Camera model SBIG ST 1602 CCD Camera Connect O Disconnect Temperature 13 51 P
117. or good quality systems a value of 0 8 0 9 is generally sufficient For bad surfaces a value of even 0 3 might be required Where The selection is done in SH Analysis Parameters The distribution of the ellipticity for the spots in any SH image as well as the flux S N ratio can be plotted by opening a cen file and selecting the plots in SH Utilities Then click the Utilities pull down menu 4 7 6 Use annulus You can ask Sensoft to include spots only in an annulus by specifying the inner and other normalized radius from 0 to 1 0 This can be useful in certain situations where elongated spots due to the turned down edge affect the analysis Default values 0 1 0 Range 0 gt 1 0 Where The selection is done in SH Analysis Parameters Note 63 This can affect the values of the aberration coefficients particularly the radial components like defocus and spherical aberration It is preferable to use the ellipticity factor section 4 7 5 to reject elongated spots at the edge 4 7 7 Combination factor The combination factor is used for the combination of the reference and mirror spots Normally the default value of 8 is sufficient It might be needed to be changed only if there is difficulty in the automatic combination of spots for example if the test optical element has large aberrations Default value 8 Range 6 8 Where The selection is done in SH Anal
118. orting graphs in JPEG or BITMAP format 4 12 6 4 The graphic toolbar rre erret eee ir idee Or x Ure bere 4 12 6 5 Printing graphs and tables sise 4 13 REJECTION OF BAD SPOTS IN A SH IMAGE ne HARDWARE 6 ee nre CPI OU ee te reb eee Er rtr Pe re E E Persei UE patena LEE MEI DD ES 4 14 2 Light source for illuminating the test element ss 4 14 3 Reference SOUFGOA x deis LL 4 15 TROUBEESHOOTING itg TRE RU E eR nn tonte inter pe Pe onu dt lentement on ein RR anus 4 15 1 Motorized collimator does not move ss 4 15 2 Firewire Camerun tie meer 4 16 CHOOSING THE RIGHT COLLIMATOR een trennen 4 16 1 Collimators available etie inde enn dee tertiae e SEEE LEE iiaia CHAPTER 5 ON LINE ADJUSTMENT OF OPTICAL SYSTEMS e eeeeeee eren eren een enne en ne tnue 84 5 1 INTRODUCTION ADJUSTING A COMPLEX OPTICAL SYSTEM eee 85 5 2 PREPARING THE SYSTEM FOR THE TEST onene eterne einen 85 5 3 USING SENSOFT FOR CHECKING THE ALIGNMENT iii 86 5 4 ALIGNMENT USING COMA AND ASTIGMATISM seen 86 5 5 ADJUSTMENT OF SPACING BETWEEN THE ELEMENTS SA3 AND DEFOCUS serrer 89 CHAPTER 6 ANALYSIS OF RESULTS 1 THE SHAPES AND INTENSITY OF THE SPOTS 92 6L INTRODUCTION a nn iter bt ER ND UE PR ESTE D ERE nn test rater 93 6 2 THE VARIOUS PLOTS AVAILABLE ee
119. os Mag Comp Sep ft f12 rm ro Dis uc 8 5 Dis put 6 BE2501 4or5 1 5 0 66 187 750 128 99 BE2502 2012 2 0 0 50 84 0 60 0 17 0 13 2 2503 25 0 4 93 7 1 75 0 21 2 16 5 2504 3 3 0 3 121 5 100 0 28 0 21 8 7 BE60 Maximum diameter DBE 58 5mm No Name BEpos Mag Comp Sep ft 12 DBE DBE Dinpur 8 5 Dinpur 6 6 Hole mm mm mm mm mm Includes BE 25 see table for BE25 above 001 11 4 2 0 24 425 7 85 3549 35 7 27 7 6002 11 4 7 0 21 416 0 75 3549 400 31 0 10 60 3549 50 2 BE6004 9 7 1 0 14 391 8 50 354 9 BE6005 8 8 9 0 11 380 2 40 354 9 1 Mag Magnification M fl2 fl Y fil fl2 2 Comp Compression 3 Sep Separation of the lenses L1 and L2 bfl1 bfl2 where bfl1 and bfl2 are the back focal lengths of the lenses 4 Boxes in red indicate that the output beam is truncated to 58 5mm 67 4 10 Computation of the normalized radius 4 10 1 Test beam overfilling and under filling the test element Note It is important for the SH analysis that the normalized radius is computed correctly especially for aspherical surfaces 4 10 2 Normalized radius no vignetting The measured diameter D should be equal to that computed theoretically as shown above for the case of an element tested in external illumination D SH test pM D The normalized diameter D is defined as norm D Dy measured norm Dg It should be 1 If it is
120. ots only if specifically requested in SH Analysis parameters the current threshold will be used You can also use the Loop option to compute the wavefront etc in a loop Specify the type of graph that you wish to see by clicking on 4 button close to Loop 73 4 11 3 On line alignment of multi component systems Enter the optical parameters in Opt Do the optical setup for taking the reference image Optimize the exposure time and take and store the reference image using Live and QAuto and Ref Do the optical setup for taking the Test image Click Live and align the Test image with the reference image using the Align command Click the Test button This will take the image of the Test element and do a full analysis with the first 7 Zernike terms Check the normalized pupil and the combination of the spots as well as other parameters that result from the analysis Click on FH and select the Align multi component system type of graphic Now check Loop on the toolbar This will start the analysis and produce a real time graph with the total values of coma and astigmatism and their x and y components The optical system can now be aligned using these graphs reduce coma and astigmatism to minimum 74 4 12 Output from Sensoft 4 12 1 Basic introduction to how Sensoft works Compute centroids of the spots for both the Lens and reference images Combine the centroids Compute the differences between the
121. ower 100 Resolution Full no binning 8 2x2 binning O 3x3 binning 9 9 binning When you connect the camera the camera cooling is automatically turned on Set the exposure time to 0 2sec and take the reference image by clicking on Ref on the dialog bar Use 2x2 pixel binning Check if the SH image is well centered You should get an image similar to the one shown later in Section 1 2 5 For the procedure of alignment and collimation the 2x2 binning medium resolution will be sufficient Select the 2x2 medium resolution and check both the Live and the QAuto boxes to adjust the exposure time This is required to get a good S N ratio without saturating overexposing the camera Start with 200 milliseconds Increase ot decrease the exposure until the background of the exposure time box in the dialog bar on the top of the screen becomes green In OptinoPro and EE versions the software can automatically regulate the exposure when the QAuto box on the dialog bat is checked Check also if the SH image is well centered If you have an uncooled camera Start with a 10 millisecond SH exposure and take the reference image by clicking on the Ref button in the dialog bar Use 2x2 pixel binning Check also if the SH image is well centered You should get an image similar to the one shown later in Section 1 2 5 Select the Live and the QAuto quick automatic exposure time boxes to adjust the exposure time This is req
122. parallel light but to one particular optical configuration that is used for the test Instrument Optino The collimator C2 can be changed easily to match the focal ratio of the lens L Calibration The aberrations of the SH system itself are removed taking a calibration image with a calibration source placed at the focus of C2 Input Values for wavefront analysis D aperture of test element ff focal length of test element fl focal length of collimator 112 Output information Along with the Zernike coefficients wavefront and the optical quality Sensoft gives diagnostics for correcting defocus coma by aligning the elements and spherical aberration by changing the separation between the elements and using a new focal plane These corrections can be based on analytical formulae or on a lookup table provided by the user for any optical element in the system Single or double pass Single pass 113 8 6 Lasers To SH system Setup laser beam appropriately attenuated is fed into Optino Instrument Optino Beam expander beam expander can be used to expand or compress the size of the output beam Calibration The aberrations of the SH system itself are removed by taking a calibration image taken with aberration free parallel light Input Values for wavefront analysis D diameter of laser beam angle of divergence M magnification or compression factor of beam exp
123. pecify the change in the size of coma in mm in the focal plane of the optical system as the element of interest is decentered by 1mm or tilted by 1 radian IV displaced in y direction TC is ve displaced in y direction TC is ve Optical axis Optical axis is tilted clockwise ve TC is ve Optical axis Optical axis Using ray tracing program decenter tilt the optical element of interest Then measure the size of the comatic image in the focal plane of the optical system The direction in which the optical element has been moved is to be noted and used when fixing the orientation of Optino see Section 4 8 1 The sign conventions are important to get the directions correctly see figure above as well as Coma definitions and sign conventions 60 4 6 4 3rd order spherical aberration SA3 calibration The program requires as input the change in the size of the image in mm in the focal plane of the optical system due to spherical aberration TSA or the transverse spherical aberration at best focus as the element of interest is moved by 1mm towards and away from the focus 2 Parakial focus SA is negative when the marginal rays cross the optical axis before the paraxial rays like in the figure above TSA is the spherical aberration at paraxial focus and is 4 times TSA LSA is the longitudinal spherical aberration For test of telescopes at Cassegra
124. pt folder BE Info toolbar Optino Pro and EE versions only when system is shipped with beam expander The toolbar displays the optical properties of the beam expander configuration selected in the Opt folder config Beso Test setup dialog bar The test setup dialog bar is displayed on the bottom of the screen when you launch Sensoft The picture of the bar and the explanation of its content fields are given below Test Flat mirror Int illum S pass Ref Use flat mirror Fux Collimation Alignment The description of the test configuration selected in Opt folder Suggestion on the setup required for the acquisition of the calibration image Flux box highlighted at the end of the SH analysis computation Check if the exposure time and then the flux was optimized in the SH image under analysis The background color of this field assumes the same colors as the exposure time box blue if flux is not enough red if the image is saturated yellow or green if the exposure time was OK box highlighted at the end of the SH analysis computation Check if the SH image under analysis was taken using parallel light The background of this filed is green if the image was collimated red if the image was taken in diverging or converging beam Alignment box highlighted at the end of the SH analysis computation Check if the SH image under analysis was aligned with respect to the
125. ptino and BE60 together LIGTH SOURCE OPTICAL FIBRE 664 1 All dimensions are in mm The height of the optical axis is 65 5mm from the base 192 Index A Actual Quality AQ 17 22 103 Alignment of multi component optical system 74 Astigmatism 14 22 35 74 75 85 86 88 163 167 168 169 170 171 172 B Back focal distance 59 61 108 Back focal length 59 61 108 156 Beam compressor 135 138 139 145 Beam expander 50 52 67 134 calibration of 148 computation of the normalized radius 68 149 different models of the motorized beam expanders from Spot optics 136 examples of getting beams of different output diameter 147 how to change the lenses 146 lens positions and magnifications for BE25 138 Magnifications available 138 principle 134 summary of magnifications for BE25 and BE60 140 using with Optino 66 Beam expander 137 C Calibration unit motorized ECM 151 152 getting diverging or converging light 155 getting parallel light with Optino Pro and EE 152 principle 152 properties of collimating lens 156 use of 152 Camera cooled CCD 177 178 exposure time 4 6 8 11 16 19 23 24 25 26 27 30 37 38 46 73 74 86 97 148 153 154 gain 7 25 26 180 uncooled 41 185 Centroids 3D and contour plots of intensity and ellipticity 100 distribution of ellipticity over the image 96 distribution of intensity over the
126. put 10 Output beam diameter Beam Expander No Beam Expander output BE25 70 60 50 9mm 40 input 30 beam 6 9mm 20 10 Output beam diameter Beam Expander No 140 9 3 4 2 Input beam diameters 8 5mm and 6 6mm The following graphs display graphically the output beam diameter for different beam expander positions The output is given for input beam diameters of 6 9mm and 9mm Beam Expander output BE25 0885 15 clin BENI 0 0 2 4 6 Beam Expander No Output beam diameter Beam Expander output BE25 70 60 50 40 put 30 s aoe 20 10 0 0 5 10 Beam Expander No Output beam diameter 141 9 4 How to get different magnifications 9 4 1 The different mounting holes for the lenses The beam expander magnifications change by changing the motorized lens L1 and the second fixed lens L2 both shown in the figure below There are 11 positions for L2 the first 7 positions are for 25mm lenses maximum beam size of 23mm and the last 4 positions are for the large lens of diameter 63 5mm maximum beam size of 58 5mm 142 iF was 354 871 143 9 4 2 Summary of lens positions The stepper motor has a step size of 021mm and has a total movement of 1700 steps giving a travel length of 35 7mm Thus different separations can be obtained between the lenses L1 and L2 depending on the position of L1 They are summarized below Table 14
127. ra lens C1 and a second camera This is used to acquire the star for an astronomical telescope as well as to get out of focus images of the telescope pupil It gives additional information on the telescope quality like zones on the mirror surface and seeing Instrument Puntino Optino It can be adapted to different focal ratios Calibration The aberrations of the SH system itself are removed by taking a calibration image with a calibration source placed at the focus of C2 Input Values for wavefront analysis 107 D ex aperture of test element fley focal length of test element fleo focal length of collimator col Other input values P The back focal distance in units of the focal length of the primary mirror used in the computations for the coma correction K Conic coefficient of the secondary mirror used in the computations of the correct focal plane from the measured value of spherical aberration as well as for computation of the movement of the secondary mirror M2 for correcting the measured value of coma due to misalignment For the sake of completeness other values of the telescope are also requested They are not used in the analysis of the wavefront Output information Along with the Zernike coefficients the wavefront and optical quality Sensoft gives diagnostics for correcting defocus by changing the separation between the mirrors coma alignment of the two elements and spherical a
128. rtmann IE EE Directories Zemikes Analysis parameters Utilities Graphics Centroiding LU Threshold Autorm c Ellipticity cutoff Reference 0 055 1 Mirror 01 O 03 Shack Hartmann Directories Zernikes Analysis parameters Utilities Reference centroids only Relax controls on reference threshold Relax controls on mirror threshold Skip reference centroiding 0 0 0 Start from combined spots The reference image should also be re analyzed whenever new values for the threshold or ellipticity cutoff are entered in the SH Analysis parameters folder The Intensity and the integrated S N ratio of the spots can be seen opening the centroid file file with cen extension from the File menu and using the Utilities option 11 1 2 7 Align the SH image from the optical system being tested with respect to the reference image taken in Section 1 2 5 Setup the optical system being tested and send the light back into Optino Define the tolerances for alignment by pressing the button close to the Align box in the Dialog bar A good tolerance limit is 20u the difference between the center of mass of the reference image and the Test images A higher tolerance may be required when testing fast lenses Tolerances for alignment X microns Y microns Check the Align check box in the dialog bar Sensoft Shack Hartmann wavefront sensors
129. s 57 Smith W J 174 Spherical aberration 22 35 59 61 64 68 75 85 108 110 111 113 115 116 119 121 124 126 130 132 155 163 164 165 168 169 170 171 Spot diagram 64 Stepper motor protocol for serial communication 158 the motor toolbar 5 troubleshooting 82 195 T Tilt 4 14 17 22 35 37 59 60 75 86 163 165 167 168 169 170 171 172 188 Triangular coma 14 22 75 168 169 170 171 Troubleshooting Firewire camera 43 82 motorized collimator 82 Z Zernike polynomials Annular expressions for first 8 terms 165 168 174 brief explanation 163 Fringe expressions for first 7 terms 165 170 Standard expressions for first 7 terms 165 169 172 used by Sensoft 162
130. s from about 5mm to 20mm For testing optical elements larger than this beam size a beam expander is required that converts the standard input beam of Optino to larger dimensions as shown below Expanded beam Input beam from Optino Motorized lens Fixed lens The magnification factor of the BE is given by M fl2 fll where fll and fl2 are the focal lengths of the two lenses L1 and L2 see above The small beam of diameter Du enters the beam expander from right and is expanded by the input magnification factor M The expanded beam from the BE is given by Dy MD input For a magnification factor M 21 1 fl2 gt fll 134 9 1 2 Main advantages The motorized lens ensures that parallel light is obtained easily Almost any magnification can be obtained by changing the lenses L1 and L2 ensuring the maximum beam sampling of the optical element A filter can be used with the fiber optic light source Thus the beam expander can be used at any wavelength see Chapter 1 Optino Pro and EE Initial setup and use Diverging or converging light can be obtained to illuminate the Test optical element 9 1 3 Beam compressor If the beam expander above is illuminated from left fixed lens L2 then it will compress the beam by a factor 1 M 9 1 4 Use in single pass and double pass The beam expander can be used either in single pass external illumination or in double pass internal illumination
131. s to fit and subtract from data Select from the following Extra terms to fit Default 02 Defocus R amp 11 Tilt RE 0 4 spherical 3rd RE 3 3triangular com amp 4 4 quadratic asp oS Higher order Astigma _ 8 Higher order TriCome R amp Higher order QuadAs a Higher order Foil Default KE Higher order Coma A Default 88 5 5 Adjustment of spacing between the elements SA3 and defocus You can use the measurement of SA3 and defocus to optimize the separation between the elements See that you have chosen to fit the first seven terms default in the SH Zernike section In the Loop param dialog choose the Aberration plot option Loop param Range of alert values for aberration coefficients From To Defocus nm 0 50 Tilt 0 50 Coma 0 50 Sa3 nm 0 50 Ast 0 50 Tricoma 0 50 QAst nm 0 50 Comas 0 50 SA5 nm 0 50 Ast5 0 50 Selecttype of plot for loop O Contour Aberrations O Align Coma Ast O Spot diagram Residuals OMi Start the Loop from the toolbar Sensoft Shack Hartmann wavefront sensor software for Optino arithmeti hotor 10 00 CO Live Auto Mff Call C MCol Fle Edit View ET Opt wes Par SH Anatysis Piot Align imulation Utilitie
132. se tenete ente entren tester en eene enne tenete 93 6 2 2 Distribution of the individual centroids over the pupil ss 95 6 2 3 3D and contour plots e ER PER nn term Se he nent ak 94 6 3 CHOICE OF PLOTS TO DISPLAY nement en ER E qe RP nn rer de EEE EE re RE RR ethos 94 iv 6 4 ON LINE AND OFF LINE DISPLAY OF THE PLOTS ccccccccccececececececececececececececececececececececececececececececesesecs 95 6 5 EXAMPLES OF THE VARIOUS PLOTS cccceseessssececececsesseaececececsenauececececeessaesecececsesenseaecececeesenssaeeeecceenes 95 6 5 1 POSitiONS Of the centroids sisisi eee eei e rere e p e ro te eee 95 6 5 2 Distribution of intensity of the spots over the image 96 6 5 3 Distribution of ellipticity of the spots over the image ss 96 6 5 4 Distribution of Signal to Noise S N ratio of the spots over the image sss 97 6 6 EXAMPLES OF 3D AND CONTOUR PLOTS OF DISTRIBUTION OF CENTROIDS rise 100 CHAPTER 7 USING EXCEL WITH SENSOFT e eeee eee ee ee ee eee ee etta sette seta setate setas eese seen aea 102 7 1 USING EXCEL WITH SENSOFT COMPARISON OF THE ZERNIKE COEFFICIENTS AND OTHER RESULTS 103 CHAPTER 8 OPTINO PUNTINO TEST CONFIGURATIONS ecce 105 8 1 GENERAL COMMENTS ON THE OPTICAL SETUP FOR TESTING WITH OPTINO AND PUNTINO 106 8 2 TEST OF TELESCOPE AT CASSEGRAIN FOCUG csssssssececece
133. space is required to store the images Used for taking the reference SH image to be used in all the subsequent SH analysis The number of images to average is selected in WFS folder The prefix to be used for reference image can be selected in the SH folder The default prefix is REF_ flat REF_ parallel REF spherical REF_pinhole according to the suggested reference setup that is specified on the bottom bar whenever a test configuration is selected in Opt Used to check the parameters for a correct analysis of the SH images The number of SH images to average is selected in WFS folder Requires a previous acquisition and analysis of the reference image The software checks for the optimum intensity in both the reference and optical system image then the optical parameters given in Opt folder are checked by computing the normalized radius of the pupil Finally fitting the first seven default Zernike terms to the data performs a standard analysis Perform the analysis of the optical system SH image 26 The number of SH images to average is selected in the WFS folder Requires a previous acquisition and analysis of the reference image After the SH image is obtained the selected Zernike terms are fit to the data and the graphs selected in the SH folder are plotted together with the table of the aberration coefficients The prefix for the lens image can be selected in the SH folder The default prefix is Lens
134. ss 145 9 5 2 BE25 used s beam compressor aes iare ee ae ee eei te tee entente 145 9 5 3 BEGO used as beam compressor aero orbe e tee ee Eee teret etae e doen 145 9 6 CHANGING THE BE LENSES chine e eite eee o pe ee o Ie gg eie Pet oe Ene ro 146 9 6 1 Howto change the BE lerises iac ee trn e or tete tae e ea ban 146 9 7 EXAMPLES OF GETTING BEAMS OF DIFFERENT OUTPUT DIAMETER ecce em nenne 147 9 7 1 BE2504 if you wish to have an output beam size of 23 mm 147 9 7 2 BE6004 if you wish to have an output beam size of 49 mm 147 9 8 STEPS FOR ADJUSTING AND GETTING THE REFERENCE SH IMAGE FROM THE BEAM EXPANDER 148 9 8 1 Calibration of the beam expander sisi 148 9 9 COMPUTATION OF THE NORMALIZED RADIUS cccssssscessssceeesssececsesaeeecsesaecsesaeeecsesaeeeceeeeeeseseeeenenaees 149 9 9 1 The test beam is larger than the aperture of the optical element and is 149 9 9 2 The beam from Optino or the BE does not fill the optical element completely 150 CHAPTER 10 THE EXTERNAL MOTORIZED CALIBRATION UNIT ECM eee 151 10 1 THE EXTERNAL MOTORIZED CALIBRATION UNIT ECM sise 152 10 1 1 Principle Of the ECM iie ep eta OR eie ame rend 152 10 1 2 Main Advant ges eer re ved eU Ru See te e ERE RR Ee d 152 LOMAS Other features ea eie eae eh e nep RR A eee estas ei e Ud 152 10 2 USING ECM rte Ron
135. sting beam splitter mounting in azimuth Mounting hole for screw for adjusting beam splitter in tip tilt amp T Nuts for adjusting mounting in tip tilt Loosen one and tighten the other tn On Fe lt gt 1 6 The internal illumination system The illumination system is attached to Optino as shown in the picture below To remove it unscrew the outer holder 1 6 1 Mounting the filter The exploded view of the illumination system is shown in the picture at left To mount the filter unscrew the 3 and then the filter retainer ring 4 Insert the filter and screw these back A filter of diameter o 25mm and thickness t 5mm can be mounted 33 To Opting flange To fiber light source Explanation 1 Pinhole holder inner diameter of mounting hole 9 5mm Filter holder max diameter of filter 25mm Max thickness 5mm Filter mounted from the left see 4 below Flange for mounting pinhole system to Optino Filter retainer Fiber optic adapter outer diameter 9 5mm Screw for adapter on Am 34 1 7 Summary of properties Table 2 Seidel coefficients Shack Hartmann analysis Zernike polynomial coefficients defocus coma astigmatism spherical aberration etc wavefront and Strehl Ratio Energy in a bucket Real time tilt adjustment of reference and lens images with graphical indication given by software Real time focus of lens images with graphical indication gi
136. t the byte with the status of the unit see explanation below is returned The inquiry for the status U lt CR gt returns a hexadecimal number composed of two parts separated by a comma In the first part the bit 7 indicates the error status When the error bit is high the second part of the status after the comma indicates the type of error Unrecognized command command Parameter out of range Time out trying to reach home position nvalid parameters in the internal memory 161 Chapter 12 Sensoft and Zernike polynomials 162 12 1 Brief explanation of Zernike Polynomials The Zernike polynomials represent a particular aberration Wat a point P in terms of the polar coordinates r Y The aberrated wavefront W can be mathematically represented in terms of a series W a a tilt_term a defocus_term 4 coma term a spherical aberration_term 4 astigmatism a triangular_coma 4 quadratic astigmatism higher order terms dy azare the coefficients of the Zernike polynomial terms that along with the zero points of the angles see below are computed by Sensoft These coefficients refer to the peak of the wavefront a is the piston term and cannot be obtained from SH analysis as its derivative is zero Note the convention that when the wavefront is retarded with respect to the ideal wavefront it is positive as the optical path length to the focus becomes long
137. t in the system Single or double pass Double pass 122 Chapter 8 Optino Puntino test configurations 8 12 Test of single lens in parallel light using a spherical mirror internal illumination Setup In the above configuration light is made parallel by the collimating lens C1 and passes through the beam splitter It falls on the element L being tested and comes to focus at F It is then reflected back into the system by the spherical mirror S The accuracy of the tests depends on the quality of the spherical mirror and the flat mirror used for the calibration Instrument Optino Beam expander A beam expander can be used to expand or compress if required for very small test elements the size of the output beam Calibration The aberrations of the SH system are removed by taking a calibration CCD image with a good quality flat mirror in parallel light before it falls on the lens L 123 Input Values for wavefront analysis D input diameter of beam from Optino D diameter of test element fl focal length of test element M magnification or compression factor of beam expander if used Output information Along with the Zernike coefficients the wavefront and optical quality Sensoft gives diagnostics for correcting defocus and spherical aberration which is minimized by shifting the focal plane These corrections can be based on analytical formulae or on a lookup table provided by the user Singl
138. t to Live Center the SH image If necessary use the Coll command on the toolbar to start the collimation process Move the stepper motor manually one step at a time until you achieve collimation white circle on the image see image below The tolerance for the manual collimation is specified in the Align Collimate page of the Par folder A good default value is 1 Focus0001 factor 0 4 SE WN ae PRN di J ee eeeeeerte ee M cu ee ll ll o M ee M ol lll ll S M OM S ee uM IN M M oe 10 201 10 1 1 1 1 1 1 1 1o 1910 L1 L2 1 NE ME M o o 11 L1 X 2 uu ww Y 75 7 2202021 1 1 1 1 1 L1 L1 ee I 1 0111 1 1 1 1 1 1 1l 9 1 ee 0 uu ux x lcl l1 1 M T ool ll ll ol o V 154 10 2 5 Getting diverging or converging light In some situations it may be required to illuminate Optino with diverging or converging light This can be achieved by Get parallel light from ECM as explained in Sections 10 2 3 and 10 2 4 above Move the stepper motor towards the Home position decreasing number of steps to get diverging light Move the stepper motor away the Home position increasing number of steps to get converging light 10 2 6 Calibration of converging or diverging light If you are using ECM with Optino Pro or Optino EE you can simply enter the defocus that you want in terms of the Zernike polynomials or the divergence angle
139. ter mmounting 31 camera settings 41 cameras available 175 changing and adjusting the beam splitter 31 148 collimation of light from test optical system 13 continuous loop 20 dimensions of 189 190 192 ellipticity cutoff 14 input parameters 58 3D 2D plots of wavefront or optical surface 62 coma and SA3 calibration 59 correlation factor 64 directories 7 11 13 17 19 21 22 23 25 62 ellipticity cutoff 63 orientation 58 65 output units 64 threshold 21 62 why focal lengths are used for flat elements 65 Zernike polynomials 22 35 62 73 75 76 155 163 164 165 166 167 169 172 light source for illuminating the test element 48 49 51 53 54 81 mounting the filter in the internal illumination system 33 off line analysis 22 73 optical parameters 13 reference source 81 summary of properties 35 system requirements for PC and laptop 40 test anaysis 14 test configuration choice of collimators 81 83 concave mirror 115 external illumination test of telescope at Cassegrain focus 107 test of telescope at Prime Newtonian focus 109 flat mirror 194 double pass 53 118 single pass 53 117 internal illumination flat mirror in Ritchey Common setup 129 human eye 127 multi component lens in parallel light using a spherical mirror 125 multiple component lens using a collimator and a flat mirror 121 single lens in parallel light using a spherical
140. th of collimator mm Recompute F and normalized pupil By entering new values for the aperture or the effective focal length of the element s under test or by changing the collimator focal length the normalized radius can be recomputed When the new value is inside the acceptance range press OK to overwrite the optical parameter values specified in Opt with the entered values You can then press the Analysis button on the dialog bar to analyze the test image with these new values or run test again Pressing Use current values anyway the old values will be kept for the next analysis and the control on the normalized pupil will be skipped pressing Cancel the program will not proceed Plot of centroids Have a look at the plot of the computed centroids see also Chapter 6 Do they look OK Are there any close double spots due to spurious reflections and other effects If yes then do one or all of the following Reduce spurious reflections Adjust the exposure time a higher S N ratio usually helps Specify a higher value of the ellipticity cutoff under SH Analysis parameters see section 1 2 11 Do an off line Analysis and increase the threshold compared to what has been found automatically SH Analysis Parameters Combined reference and Mir spots Is the plot of the combined reference and lens images OK Are there any obvious wrongly combined spots 16 Wavefront and Zernike coefficien
141. the MColl command applied to the beam expander 28 File menu Open SH result file cof Open Image file fit Open Image file tif Open centroid file cen Close Close all Load optical configuration Save optical configuration Save Save As Print Ctrl P Print Preview Print Setup Rename file Rename set of files Recent SH results cof Recent image files fits Recent image files tif Recent centroid files cen wuw ae Open all the files supported by Sensoft Output results file with cof extension Image files with fit extension Centroid file with cen extension Image with extension tif can be also opened and displayed by Sensoft but not analyzed To analyze these images you should convert them into fit format using the Save As function in File Menu Close active view file on the display Close all views files on the display Load Save configuration files with all the parameters specified in Sensoft dialogs that can be useful for the analysis of the optical system under test Save images and graphs Print the current image graphic on the display on the default printer Rename a single file or a group of files Open the most recent file created by Sensoft Image arithmetic Menu Perform image arithmetic on images 29 Info Toolbar The Info toolbar gives the information about the optical setup and optical parameters entered in the O
142. thout collimator Multiple lens in parallel light without collimator Human eye Flat mirror in Ritchey Common setup Spherical mirror Flat mirror Flat mirror Flat mirror Spherical mirror Spherical mirror Flat mirror Flat mirror Spherical mirror Spherical mirror None 2F mir F col 6 6mm F lens F col 6 6mm F lens F col 6 6mm F lens F col None F lens F col None F lens F col 6 6mm F lens F col 6 6mm F ens F col 6 6mm F eye F col None F lens F col 131 Notes For calibrating Optino for use with the laser a parallel calibration source is required The maximum diameter tested 6 6mm refers to the standard camera It can go up to 19mm with a larger camera Using a beam expander the maximum aperture of the optical element being tested can go up to 400mm For flat mirrors a collimator focal length of 100mm is assumed F denotes focal ratio S Single pass Wavefront is multiplied by a factor of 1 D Double pass Wavefront is multiplied by a factor of 0 5 The last three columns refer to the correction for the calibration of the defocus 3rd order spherical aberration and coma 132 Chapter 9 Motorized Beam Expanders from Spot Optics 133 9 1 Motorized beam expanders from Spot optics 9 1 1 Motorized beam expander principle Depending on the model the exit beam from Optino in the internal illumination mode varie
143. to the plate as explained in section 4 8 1 values can be saved and loaded from a default file using the Load Save optical configuration function in the File menu SH Select the directory for storing results from on line and off line analysis 25 Select the SH images to be used for analysis in off line mode Select the Zernike terms to be fit to the data Specify the threshold and ellipticity parameters for centroiding Select the output graphs that you wish to see after the analysis is over Use the utilities option Plots the output graphs for SH analysis without running the program again The output table of any previous run e g using the open command must already be open Analysis Live Used for running the SH analysis program in off line mode For starting stopping the camera exposure QAuto Auto Dark Ref Test Lens For quick automatic optimization of exposure time Use this feature when you can see a non empty dark image on the screen For automatic optimization of exposure time Sensoft is shipped with the dark images already stored on the CD These images are copied to the appropriate directory where Sensoft is installed Click this button if for any reason you need to redo the dark calibration A series of dark calibration images for the Shack Hartmann camera will be taken automatically Images will be taken up to 100msec of exposure and with different gain factors About 120Mb of disk
144. tomatically when the MColl box is checked See Section 1 3 Optino getting parallel light with the motorized collimator Alternatively the Coll command can be used to start the collimation process The motor is moved manually using the Collimator toolbar see Section 1 2 1 The tolerance for the collimation can be specified by pressing the button close to the Coll box in the Dialog bar A good tolerance limit is 0 2 or less Tolerances for collimation Tgrance 0 1 10 In Optino Uno the collimator is preset before shipment though it can be moved manually if required The suffix for the reference image will be given automatically by the program and depend from the reference test setup corresponding to the optical test setup selected in the Opt folder The test setup and the suggested reference setup are displayed on the bar shown in the figure below which appears on the bottom of the screen when you launch Sensoft Test Flat mirrer Int illum S pass Ref Use flat mirror Flux Collimation Alignment Sensoft Shack Hartmann we ont sensor software for Optino File Edit View Image arithmetic CCD Motor Align mulation _ _ Opt Wes SH fAnatysis Ptot 1725 Live O Auto 5 Measure C 1 Caign 7 cot mco imulation Utilities Help Press the Ref button on the dialog bar A dialo
145. ts Does the wavefront look OK In the Test the first 7 Zernike terms are fitted Do they look reasonable You can review the output result file also off line by opening the file Test0001 cof from the File menu and selecting the graphs that you want to display in the SH Graphics and SH Utilities folder 1 2 13 Do a full analysis by using the Lens button Go to the SH Directories folder and select the string to be used as prefix for the Lens image The string assumed as default is Lens Shack Hartmann Directories Zemikes Analysis parameters Utilities Graphics Selectcreate directory for results Select Reference image C sensoff Ref0002 fit Select Lens image s CAsensoft Test0001 fit Prefix for len image s good Go to the SH Zernikes and choose the Standard Zernike coefficients to fit to the data We recommend that to start with the 7 terms grouped under the Default item The selection is done with a simple drag and drop of groups or individual terms from the central window to the window at left Also specify if you wish to see the wavefront or the surface Select the Actual Quality definition as Tilt only or Tilt and Defocus 17 Shack Hartmann Directories Zemikes Analysis parameters Utilities Graphics Terms to fit and subtractMn data Select from the following Extra terms to fit K Default Hi
146. uired to get a good S N ratio without saturating overexposing the camera Increase or decrease the exposure until the background of the exposure time box in the dialog Bar on the top of the screen becomes green In OptinoPro and EE version the software can automatically regulate the exposure when the QAuto box on the dialog bar is checked Check also if the SH image is well centered 1 2 3 Align the Shack Hartmann camera The uncooled SH camera is mounted before shipment with the rows and columns along the horizontal and vertical directions The alignment of the SH camera can be done by loosening two screws holding the mounting of the camera at the top and left or bottom using Allen keys Once this has been done tighten the hex screws on the top and side or bottom of the flange holding the camera Note The alignment of the SH camera is important the SH spots should be aligned along the rows and columns with a precision of about 1 pixel 1 2 4 Take the dark calibration for the Shack Hartmann camera The dark calibration for your camera has been already taken and stored in the subdirectory Dark of the Sensoft installation CDROM The full content of the Dark subdirectory 5 subdirectories with 100 files each must be copied into the directory where Sensoft has been installed The procedure described below is required only if for any reason you need to take a new dark calibration Cover the instrument and switch
147. unction of no of spots Maximum normalized radius o b Roin La 6 i 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 No of spots in X or direction 72 4 11 Off line and on line analysis Analysis can be done in two ways 4 11 1 Off line analysis Enter the optical parameters in Opt Go to SH setup select the reference and Test image names Specify the Zernike polynomials chosen for the fit in SH Zernikes Choose the graphs that you wish to see after the analysis SH Graphics Click the Analysis button Check the results and the graphs 4 11 2 On line real time analysis Enter the optical parameters in Opt Do the optical setup for taking the reference image Optimize the exposure time using Live and QAuto take the reference image with Ref Do the optical setup for taking the Test image Click Live and align the Test image with the reference image using the Align command Click the Test button This will take the image of the Test element and do a full analysis with the first 7 Zernike terms Check the normalized pupil and the combination of the spots as well as other parameters that result from the analysis You can choose to rename the Test results by using the Rename command under File menu Now click the Lens button It will do a full analysis using the Zernike coefficients that you have chosen to fit An automatic threshold will be used for detecting the sp
148. uracy obtained with any system depends on its calibration against an external reference The light reaching the camera that records the spots passes not only through the Test element but also through other optical elements including the lenslet array window of the camera beam expanders etc This is the case also for an interferometer Then it becomes important to calibrate out the aberrations of these additional systems The calibration of these systems usually using a spherical or flat mirror sets the final accuracy achieved Thus calibration is a very important part of any metrology like interferometers and a lot of effort goes into doing it correctly if good results are to be obtained In addition in the case where the Test system is illuminated with an external light source flat or spherical mirrors are not used for the calibration The purity of the illumination system then sets the final accuracy Spot optics products for the calibration have been developed after extensive testing 4 4 2 Repeatability Precision 4 4 2 1 Wavefront With the uncooled camera Better than 3nm rms 4 125 With the cooled camera Better than 2nm rms 4 300 Here A 632 nm 4 4 2 2 Zernike coefficients The Zernike coefficients are obtained with a repeatability of better than 2nm rms 56 4 4 3 Accuracy The accuracy of the test depends on the purity of the light illuminating the system as well as the optical system used to calibrate o
149. ut any auxiliary optical system used like beam expanders 4 4 3 1 External illumination mode Pinhole light source Aberrations of the light source point source or parallel light These are typically free from aberrations as a special system for illuminating the very small pinhole gives pure light Parallel light source The light from the pinhole is made parallel by the collimator which can be a lens or a mirror or a complex optical system The achromatic collimators used by Spot optics have a diffraction limited performance at the design wavelength of 632nm typical accuracy better than 4 8 Other systems give an accuracy of A 8 4 4 3 2 Internal illumination mode Light source The same pinhole light source with collimator is used both for illuminating the test element and for obtaining the reference image In this case the aberrations due to the source alone cancel out and the final accuracy reached is independent of the light source Spherical or flat mirror Spherical or flat mirrors with a typical accuracy of 4 20 determine the final accuracy achieved They are commercially available from companies like Zygo and Edmund Optics 4 4 4 Which test to use Since the test in internal illumination 1s independent from the quality of the light source since both the reference and Test image are obtained with the same source it should be the preferred choice when the highest accuracy is required 57 4 5 Input 1 Opti
150. ven by software Image analysis Wavelength range 0 35 1 06p Optino Vis 0 7 0 4 1 6 Optino IR 35 Chapter 2 OMI Optino Minisensor Initial setup and use 36 2 1 OMI getting started How to get a good SH image Note Square brackets refer to commands of Sensoft OMI can be supplied either with a cooled SBIG camera or with an uncooled Firewire IEE1394 camera check which camera has been supplied with your system Switch off the PC If the OMI hardware includes a cooled camera Connect the SH CCD to any of the USB ports of your PC using the USB cable provided with OMI Connect the power supply and switch it on Wait until the red led on the back of the camera box is on When you launch Sensoft go to the WFS section and select to connect the camera The temperature regulation will be automatically started and the camera temperature will be regularly refreshed in the status bar on the bottom of the display Wait until the temperature is close to 0 C If the OMI hardware includes an uncooled camera Connect the digital FireWire camera to the FireWire PCI adapter or a built in FireWire port card in the case of a PC or to the PCMCIA FireWire adapter card dongle in case of the laptop using a FireWire cable with a 6 pin connector Switch on the PC Launch Sensoft Optino and fill in the parameters in the Opt section Switch on the light source for illuminating OMI place a flat mirror at the exit hole
151. wavefront of distortion 8 ECM25 and ECM60 and 4 ECM120 4 14 3 Reference source The reference light source Pin50 is used for calibrating out the aberrations of the collimator C2 Optino It is placed it at the focus of C2 81 4 15 Troubleshooting 4 15 1 Motorized collimator does not move When the stepper motor controlling the collimator or the beam expander lens does not function correctly try the following Check the power supply 12V 500mA Check that the power supply parity is correct inner positive The power output is set to the right voltage 12V Check that the power connector is of the right size Check the serial connection to PC Touch the lead screw of the motor 4 15 2 Firewire Camera If the camera does not respond to the commands from the PC disconnect the Firewire cable and attach it again 82 4 16 Choosing the right collimator 4 16 1 Collimators available Below is a list of collimators that are available The focal ratio has been computed for a beam size of 7mm Please contact us for faster focal ratios How to use the table Choose the collimator that has a focal ratio equal to that of the optical element being tested If that is not available choose the nearest focal ratio that is larger This will give a smaller sampling of spots by a factor that is equal to the ratio of the two focal ratios For example when testing an f 5 spherical mirror at its radius if curvature thus
152. wish to see the distribution of ellipticity for the very highly elongated spots also set the rejection limit for amp 1 and retry the analysis If the combination of the spots from the reference and optical system fails lower the rejection limit of and try again Please see Chapters 1 and 4 for more details 6 2 The various plots available 6 2 2 Distribution of the individual centroids over the pupil The following graphs are available both for the reference and for the lens image Distribution of the centroids of the spots used for computing the shape of the surface and the coefficients of the Zernike terms Ellipticity distribution of the spots used for identifying irregular shape of the area 300 from which the spot originates 93 Intensity distribution of the spots used for measuring reflectivity S N Signal to Noise ratio distribution of the spots same as intensity distribution but takes into account also the noise of the camera 6 2 3 3D and contour plots The intensity and ellipticity distribution better represent the form of 3D and contour plots They can be plotted to look for any vatiation Furthermore after the combination of the lapping plate vs reference centroids the second step in the Shack Hartmann analysis a 3D and contour of intensity of the spots normalized with respect to the image assumed as reference for the analysis The normalization takes into account any non uniformity in the calibrat
153. x y positions of all the pairs of combined spots and compute what are termed as residuals Fit the derivatives of the chosen Zernike polynomials to the data and compute the coefficients and their angles Compute the wavefront after at least subtracting out the effect of the tilt Zernike coefficient as tilt results from the imperfect alignment between the Lens and reference images Compute the Strehl Ratio Up to this point the basic computations have been done to get the Zernike coefficients and their angles Compute the spot diagram and the Encircled Energy This is in the focal plane of the converging lens For flat surfaces a perfect lens of focal length 100mm is assumed 4 12 2 Some definitions After the computations of the Zernike coefficients Sensoft will let you subtract out the contributions of the aberrations and look at the resulting or residual wavefront D80 etc 4 12 2 1 AQ Actual quality For converging elements this refers to the quality of the optical element after the subtraction of the contribution of tilt and defocus as computed from the Zernike coefficients For flat elements this refers to the quality of the optical element after the subtraction of the contribution of tilt as computed from the Zernike coefficients 4 12 2 2 RQ Residual quality For all the elements this refers to the quality of the optical element after the subtraction of the contribution of the Zernike coefficients fit by the us
154. xpander if already mounted as explained in sections 3 7 above Attach the beam expander to Optino using the appropriate coupling ensuring that the pins enter the front plate of Optino correctly Tighten the setscrews at the top and side of the BE Mount a good quality flat mirror flush pushed firmly against the faceplate of the BE exit Switch on the calibration light source and start the Live exposure Adjust the exposure time light intensity to get optimum exposure of the SH spots by using the QAuto or Auto command The aim is to center the SH image returning from the front mirror by adjusting the beam splitter see Chapter 1 Optino Pro and EE Initial setup and use section 1 4 Changing and adjusting the beam splitter Slide out the top cover of Optino You might wish to remove the side cover also to have easy access to the set screws on the side of the beam splitter mounting Adjust the beam expander till the SH image is centered on the camera Now mount the fixed lens L1 and the movable lens L2 according to the expansion factor desired as explained in sections 3 7 above Using the Coll button like for Optino move the motor of the BE to get parallel light Alternatively use the MBexp button Once the alignment is done this is the reference SH image for the subsequent analysis of your optical system when used with the beam expander Take the Test image aligning it carefully with the reference image taken in Step 10 tolerance
155. y is at upper left Sensoft follows the standard Cartesian system y increasing upward This reversal is taken into account by the software The angles ofthe Zernike coefficients are measured counterclockwise from X axis The origin of this system is atthe center of the pupil See Help Load default Save as default 4 8 2 Why focal lengths are used for flat elements Clearly for flat elements e g mirrors and filters the focal lengths fl and flo not required test However Sensoft allows you to see the spot diagram corresponding to the wavefront from a flat element as if it were focused by a perfect lens of a given focal length By default Sensoft sets fl 100mm test 65 4 9 Motorized beam expander of Spot Optics 4 9 1 Using Optino with motorized beam expander compressor Expanded beam Beam expander Input beam from Optino Motorized lens L1 Fixed lens L2 Depending on the model the exit beam from Optino in the internal illumination mode varies from about 5 to 20mm For testing optical elements larger than this beam size a beam expander is required that converts the standard input beam of Optino and expands it as shown above The beam expander can also be used to expand a laser beam external illumination mode It can also be used to compress a beam both in internal and external illumination mode This is useful for testing small opti
156. y up to 1 061 and thus can be used to test the Nd Yag laser as long as it is bright 14 2 2 Characteristics 1280 x 1024 pixels 7 5u pixel size 9 6mm x 7 6mm 10 Bits ADC resolution Mirror and flipped scan modes Programmable gain 0 14 dB Dynamic range 66 dB 14 2 3 Quantum efficiency Quantum efficiency of Standard CMOS camera of Optino QE 420 436 500 550 600 650 700 800 880 950 1100 Wavelength nm 180 14 3 Cooled camera 2 325 1100nm 30x30 spots small pixels slower read out 14 3 1 Cooled digital camera with CCD sensor The Peltier cooled CCD camera from SBIG model 10XE is offered as an optional camera tis ideal for use in the UV down to 350nm Given its small pixel size it can cover the wavelength range from 350nm 1100nm Since the camera is cooled long integration times can be used This is especially useful when the flux of the light source is low e g for narrow band filters USB controlled Pixels can be binned Download time 8 7sec full frame without binning 14 3 2 Characteristics 2184 H x 1472V Pixels with enhanced Spectral Response 6 8 x 6 8 pixels 2x2 and 3x3 binning 13 6 x 13 6 and 20 4 x 20 4u 14 85mm H x 10 26mm V Photosensitive Area High Output Sensitivity 20LV e 78 dB Dynamic Range Low Dark Current lt 7pA cm2 250C 14 3 3 Quantum efficiency Relative Quantum Efficiency KAF 3200ME vs KAF 3200E g
157. ysis Parameters 4 7 8 Correlation factor This is for the advanced user who is interested in analyzing the cross talk between the various Zernike coefficients computed by Sensoft You can set the value of the probability range 0 to 1 0 when the computed probability is greater than the value specified Sensoft will print them out Default value 1 Range 0 1 Where The selection is done in SH Analysis Parameters 4 7 9 Output units 4 7 9 1 Spot diagram distribution of residuals Encircled Energy profile The units can be either arcsec of microns Default unit microns Where In SH Graphics 4 7 9 2 Wavefront For the wavefront the output can be either in nm or waves in units of the wavelength specified in Opt Default unit nm Where In SH Graphics 64 4 8 Notes on the input parameters 4 8 1 Orientation The orientation of the pupil coming from the test system can be calibrated with respect to the mounting of the optical system like Left Right Top and Bottom The simplest way to do this is to cover the Top part of the beam and then note the obscuration on the SH image Repeat it for the Right side Enter this in the section WFS as shown below The orientation is used in the plots of the wavefront surface as well as for the indications given by Sensoft to correct for coma WFS setup SH camera Collimator BeamExp Orientation Down x Right Y The origin of the image displa

Optino manual

Contents

Download Pdf Manuals

Related Search

Related Contents