Demetrio Magrin INAF Astronomical Observatory of Padova demetrio
Demetrio Magrin INAF – Astronomical Observatory of Padova demetrio. magrin@oapd. inaf. it Optical Design Catania, 11/06/2014
Outlines Design parameters (Definition phase) Nominal Baseline (Definition phase) Nominal Performances (EE, spot diagram, PSFs, vignetting factor) Sensitivity and thermal analysis Breadboard – Prototype New (Last…) Baseline Open Issues
Design parameters Spectral range Entrance Pupil Diameter Working F/# Field of View 500 – 1000 nm 120 mm 2. 06 @ 700 nm 1151. 5 degree 2 Image quality 90% Enclosed energy < 2× 2 pixel 2 over 1108. 3 degree 2 Maximum Field Distortion Plate scale Pixel size CCD format FPA size Optical elements weight Working Temperature Working Pressure 5. 043% 15 arcsec/pixel 18 micron 4510× 4510 (× 4) pixel 2 164. 36 mm (2 mm CCDs gap) 5 Kg (<6 Kg) -80°C 0 atm
Nominal Design Definition phase (18/03/2011) BK 7 (G 18) S-FPL 51 BK 7 N-KZFS 11 S-FPL 53 196. 2 mm Ca. F 2 368 mm KZFSN 5
Nominal Design Definition phase (18/03/2011) window Lens 1 Lens 2 Lens 3 Lens 4 Lens 5 Lens 6 FPA S 1 S 2 S 3 S 4 S 5 S 6 S 7 S 8 S 9 S 10 S 11 S 12 S 13 S 14 S 15 R Thickness (mm) infinity 6. 000 infinity 2. 000 177. 857 23. 000 infinity 27. 351 795. 855 7. 000 135. 943 56. 975 151. 697 23. 000 -225. 536 59. 886 -742. 200 17. 000 -139. 241 16. 240 -101. 194 5. 000 -144. 005 115. 547 -103. 083 5. 000 infinity 4. 000 infinity Glass K a 4 a 6 BK 7 G 18 S-FPL 51 Shape circular -3. 681 3. 605 E-8 -4. 020 E-12 circular NKZFS 11 circular CAF 2 circular S-FPL 53 circular KZFSN 5 circular N-BK 7 (G 18) circular square Diameter (mm) 190 178 142 130 114 116 130 131 129. 6 135. 4 154 184
Aspheric surface S-FPL 51 Maximum deviation from BFS 1. 050 mm See R. Ragazzoni presentation
Enclosed Energy G 0 V + detector QE 2 x 2 pixels
Enclosed Energy (through focus) -40 micron +40 micron
Spot diagrams and Fo. V 4 x 4 pixels 13. 6 deg, 13. 6 deg 14. 3 deg, 14. 3 deg
About vignetting Natural vignetting 9. 0% at the edge of the full Fo. V 7. 5% at the edge of the ‘in spec’ Fo. V
About vignetting Mechanical vignetting 6. 4% at the edge of the full Fo. V 4. 2% at the edge of the ‘in spec’ Fo. V
About vignetting Natural + Mechanical vignetting 15. 4% at the edge of the full Fo. V 11. 7% at the edge of the ‘in spec’ Fo. V
Polychromatic PSFs PLATOSim
Sensitivity Analysis Element L 1 L 2 L 3 L 4 L 5 L 6 Decentering (+/- in micron) 80 100 30 60 60 100 Tilt (+/- in degrees) 0. 07 0. 05 0. 03 0. 05 0. 10 Optical elements defocus 30 -50 micron Merit Function: 80%EE< 2× 2 pixel 2 over the corrected Fo. V
Thermal Analysis • In the case of the of a uniform change of the temperature the optical system has 2 C of tolerances without the need of refocusing. With a temperature change of 10 C the nominal performances are still recoverable by applying a defocus through the three resistors. • In the case of temperature gradient around the nominal temperature, the optical system maintain the nominal performance with a T=5 C without the need of refocusing. While the performances are recoverable by applying a defocus in the case of a T=10 C.
Bread. Board/Prototype Design The baseline design has been modified to allow the SESO tools adaptation (surfaces curvatures) and to facilitate and to speed up the manufacturing and mounting processes (some thicknesses and apertures have been increased). For procurement reasons, the glass of L 5, KZFSN 5, has been substituted by NKZFS 5. (J. Farinato / presentations) V. Viotto / M. Bergomi
My last ‘New Baseline’… 21/05/2011 1) A physical stop in front of L 3 (at about 2. 84 mm edge to edge). 2) New weights for the wavelengths used in the Zemax merit function provided by P. Levacher - P. Bernardi. 3) Change the glass of L 5 from KZFSN 5 to NKZFS 5 (almost no optical impact and facilitate the procurement). 4) Change thicknesses of L 5 and L 6 from 5 mm to 7 mm (all the industries suggested to increase these numbers). 5) Change on all lenses apertures from 1 mm to 2 mm with respect to the clear aperture. It should help to minimize the mechanical vignetting.
Open Issues Data mining… (about 3 years to resurrect). Converge on a well-identified design to use as baseline. Optimize the design for new/modified requirements. Plate scale, PSF size, window material and thickness, 2 F-TOUs dedicated design. Perform a detailed manufacturing/alignment tolerances and consolidate sensitivity/thermal analysis. RUAG warnings: the design is tight/ de-spacing tolerances are sub-micron. Double-check performances in terms of EE/Simulator Contact SESO and discuss the upgrade from breadboard to prototype with the related implications.
- Slides: 18