Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.arcetri.astro.it/~carmelo/CD_Cover_Characterization.pdf Äàòà èçìåíåíèÿ: Mon Oct 4 12:47:14 2004 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 03:53:18 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: http astrokuban.info astrokuban

CD COVERS CHARACTERIZATION
C. ARCIDIACONO, A. BRINDISI AND S. KELLNER

Contents 1. Intro duction 2. Setup 3. Measurements pro cedure 4. Data 4.1. Screen 1 4.2. Screen 2 4.3. Screen 3 4.4. Screen 4 4.5. Screen 5 4.6. Screen 6 4.7. Screen 7 4.8. Screen 8 4.9. Screen 9 4.10. Screen 10 5. Conclusion 1 1 2 2 3 5 7 9 11 13 15 17 19 21 23

1. Introduction In this report the results of the characterization of the CD covers are listed. These screens were cut by Stephan Kellner at the MPIA laboratory in Heidelberg. The characterization was performed by using the interferometer in the Arcetri Adaptive Optics Laboratory. We analyzed 10 different CD screens and for each one we computed the wavefront distortion. We fixed a system of co ordinate on each screen defining the co ordinate axis the bottom left corner as origin. We labeled each screen writing the identification number in the bottom right corner. We measured on each screen the distorsion on a pupil of 50.8 mm (defined by the reflecting surface used in the setup). This pupil was identified on the CD cover by two (black picted) points at 36 mm and 84 mm in the x­direction and 55 mm in the y­direction (both). These two points were used as reference in positiong phase of the screen in front of the interferometer. In this way the centre of the pupils is at the 60 mm (x) and 55 mm (y) from the bottom left corner of the CD cover. 2. Setup We put in front of the interferometer (150 mm) the optical CD cover and the reflecting surface (300 mm from the interferometer). We checked the fringe contrast given by different surfaces (flat mirror, plane­concave lens, Esposito­neuter­filter and Ragazzoni­50/50­beam splitter) and we noted that the optimal solution was achived with the 2 inchs 50/50 beam splitter. The beam
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C. ARCIDIACONO, A. BRINDISI AND S. KELLNER

splitter was fixed while the CD covers were mounted on a linear stage in order to properly positionate the pupil on the screen (using the two dots). The WYKO program of the interferometer was used to retrieve the measurements from the interferometer itself. 3. Measurements procedure For each screen we measured 10 times the static aberration intro duced by the beam splitter and the aberration due to the both (CD and beam splitter) At the end the measurements were saved and averaged. 4. Data


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Figure 1. Screen case 1. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 1 0.39 0.39 1369.71 0.86 2817.05 25.28 Table 1. Results relative to the computed average and relative to the screen 1. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.1. Screen 1.


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C. ARCIDIACONO, A. BRINDISI AND S. KELLNER

Figure 2. Screen case 1. Here are represented the value of the Zernike co efficients.

Figure 3. Screen case 1. Here are represented the illumination of the 4 pupils.


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Figure 4. Screen case 2. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 2 0.84 0.83 193.74 0.50 990.54 10.13 Table 2. Results relative to the computed average and relative to the screen 2. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.2. Screen 2.


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C. ARCIDIACONO, A. BRINDISI AND S. KELLNER

Figure 5. Screen case 2. Here are represented the value of the Zernike co efficients.

Figure 6. Screen case 2. Here are represented the illumination of the 4 pupils.


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Figure 7. Screen case 3. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 3 0.90 0.89 230.31 0.45 849.34 9.30 Table 3. Results relative to the computed average and relative to the screen 3. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.3. Screen 3.


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C. ARCIDIACONO, A. BRINDISI AND S. KELLNER

Figure 8. Screen case 3. Here are represented the value of the Zernike co efficients.

Figure 9. Screen case 3. Here are represented the illumination of the 4 pupils.


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Figure 10. Screen case 4. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 4 0.76 0.76 204.50 0.56 866.41 11.39 Table 4. Results relative to the computed average and relative to the screen 4. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.4. Screen 4.


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C. ARCIDIACONO, A. BRINDISI AND S. KELLNER

Figure 11. Screen case 4. Here are represented the value of the Zernike co efficients.

Figure 12. Screen case 4. Here are represented the illumination of the 4 pupils.


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Figure 13. Screen case 5. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 5 0.71 0.71 258.41 0.60 870.22 12.29 Table 5. Results relative to the computed average and relative to the screen 5. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.5. Screen 5.


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C. ARCIDIACONO, A. BRINDISI AND S. KELLNER

Figure 14. Screen case 5. Here are represented the value of the Zernike co efficients.

Figure 15. Screen case 5. Here are represented the illumination of the 4 pupils.


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Figure 16. Screen case 6. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 6 0.52 0.52 289.20 0.76 962.45 17.89 Table 6. Results relative to the computed average and relative to the screen 6. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.6. Screen 6.


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Figure 17. Screen case 6. Here are represented the value of the Zernike co efficients.

Figure 18. Screen case 6. Here are represented the illumination of the 4 pupils.


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Figure 19. Screen case 7. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 7 0.60 0.60 287.55 0.70 1000.34 15.03 Table 7. Results relative to the computed average and relative to the screen 7. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.7. Screen 7.


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Figure 20. Screen case 7. Here are represented the value of the Zernike co efficients.

Figure 21. Screen case 7. Here are represented the illumination of the 4 pupils.


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Figure 22. Screen case 8. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 8 0.63 0.62 331.20 0.68 1020.50 14.32 Table 8. Results relative to the computed average and relative to the screen 8. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.8. Screen 8.


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Figure 23. Screen case 8. Here are represented the value of the Zernike co efficients.

Figure 24. Screen case 8. Here are represented the illumination of the 4 pupils.


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Figure 25. Screen case 9. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 9 0.73 0.73 307.99 0.59 828.93 11.94 Table 9. Results relative to the computed average and relative to the screen 9. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.9. Screen 9.


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C. ARCIDIACONO, A. BRINDISI AND S. KELLNER

Figure 26. Screen case 9. Here are represented the value of the Zernike co efficients.

Figure 27. Screen case 9. Here are represented the illumination of the 4 pupils.


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Figure 28. Screen case 10. On the left there is plotted the average of the 10 measurements taken into account computed directly from the program WYKO. On the right the same average measurements but coming from the pyramid simulation. Case WF rms Phase Average SR Peak to r0 at µm rms rad nm valley nm 6300nm Screen 10 0.59 0.59 264.20 0.71 859.61 15.37 Table 10. Results relative to the computed average and relative to the screen 10. The phase are computed at the wavelength of the laser (6.3µm). The r0 refers to a aperture of 8 meters diameter and suppose a Kolmogorov Power Spectrum. 4.10. Screen 10.


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Figure 29. Screen case 10. Here are represented the value of the Zernike co efficients.

Figure 30. Screen case 10. Here are represented the illumination of the 4 pupils.


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5. Conclusion The CDs were characterized properly but they present almost the same optical behaviour. We cannot use different portions of the screens because at the edge they present only a huge tip­tilt and only close to the centre we found the best characteristics of the aberration. So we need more screen taken from different CD cover factories, or, at least, from different CD box sets.

Figure 31. The general case. Here are represented the value of the Zernike co efficients rms of the ten cases taken into account.