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Roberto Ragazzoni INAF – Astronomical Observatory of Padova email@example.com Telescope optics ASI Headquarter - Rome, January 29th, 2000 On behalf and with extensive inputs from the Telescope Group (D. Magrin, D. Piazza, J. Farinato, S. Basso, M. Ghigo, M. Munari, P. Spano’, G. Piotto, E. Pace, S. Scuderi, I. Pagano, L. Gambicorti, C. Arcidiacono, R.U. Claudi, V. Viotto, M. Dima, G. Gentile, R. Canestrari, S. Desidera, S. Benatti) Timeline… ESTEC 2nd June 2008: claimed a new optical design is possible and useful First telescope group meeting end of 28th Aug. 2008 Meeting in ESTEC, 9th Sept. 2008 Meeting in Bern 24th Sept. 2008 Second telescope group meeting, 25th Sept. 2008 Third telescope group meeting, 18th Nov. 2008 ESTEC meeting 28th Nov. 2008 7 meetings, various optical design, always a current optical design… In the last ESTEC meeting decision to trace a new baseline with an all-refractive, 14..15arcsec/pixels scale!!! Requirements and design drivers Payload Definition Document (PDD) Spectral Range > 500 m Field of view ≥ 500 degree2 PSF size 90% en-squared energy 2×2 pixel2 PSF Flat-topped (defocused) Collecting Area ~ 100 cm2 × 28 telescopes EPD ~ 112.8 mm EPD unique telescope ~ 597 mm Plate scale 12.5 arcsec/pixel Detector format 3584×3584×4 Pixel size 18 m ESTEC Optical Design 809 mm Spectral Range 400 – 1000 m L1 M2 Field of view <634 degree2 Silica SiC Aspheric Aspheric Image quality 90% EE 2x2 pixel2 (Stop) NO PSF Flat-topped FPA Collecting Area ~83-105 cm2 412 mm (Vignetting) L2 BK7 Plate scale 12.5 arcsec/pixel Aspheric Optical elements 5.91 Kg mass M1 FPA size 130 mm SiC Aspheric ESTEC Optical Design 809 mm Spectral Range 400 – 1000 m L1 M2 Field of view <634 degree2 Silica SiC Aspheric Aspheric Image quality 90% EE 2x2 pixel2 (Stop) NO PSF Flat-topped FPA Collecting Area ~83-105 cm2 412 mm (Vignetting) L2 BK7 Plate scale 12.5 arcsec/pixel Aspheric Optical elements 5.91 Kg mass M1 FPA size 130 mm SiC Aspheric Still baffling undoable and performances far from the published one from the .Zmx files we have got so far (9th Sept. and later). We now think this is unrelevant today Refractive Optical Design 437 mm Spectral Range 500 – 900 m L1 CaF2 Field of view 550 degree2 L5 Aspheric L2 L3 L4 CaF2 Image quality 90% EE 2×2 S-TIM35 S-LAH79 CaF2 Aspheric pixel2 NO PSF Flat-topped Collecting Area 100 cm2 192 mm EPD ~ 112.8 mm FPA Plate scale 11.8 arcsec/pixel Optical elements 5.24 Kg Stop mass FPA size 129 mm Field Distortion 4.52% Refractive Optical Design 437 mm Spectral Range 500 – 900 m L1 CaF2 Field of view 550 degree2 L5 Aspheric L2 L3 L4 CaF2 Image quality 90% EE 2×2 S-TIM35 S-LAH79 CaF2 Aspheric pixel2 NO PSF Flat-topped Collecting Area 100 cm2 192 mm EPD ~ 112.8 mm FPA Plate scale 11.8 arcsec/pixel Optical elements 5.24 Kg Stop mass FPA size 129 mm Field Distortion 4.52% Lighter, more compact, same performances, thermal main concern! New Requirements Optics specifications: V 2.0, October 27th, 2008, Lucien Hill, Patrick Levacher Spectral Range 450-1000 m (400 – 1100 m) Field of view ≥ 500 degree2 (132x132 mm2, 133x133 mm2) PSF size range +/-50 m 90% EE diameter < 30 arcsec 90% EE diameter > 30 m (20 arcsec) cross sections Collecting Area ~ 110 cm2 x 30 telescopes EPD ~ 118.7 mm EPD unique telescope ~ 650 mm Plate scale ≤ 12.0 arcsec/pixel (Variation < 10%) Field Distortion < 1% (stability<0.1% over the Temperature range) Detector format 3584x3584x4 Pixel size 18 m “New” Refractive Optical Design 421 mm Spectral Range 450 – 1000 m L1 BaF2 L5 Field of view 550 degree2 Aspheric L3 L4 N-LAK22 L2 Image quality 90% EE 2.5×2.5 pixel2 N-PK52A BaF2 Aspheric LAFN7 Collecting Area 100 cm2 EPD ~ 112.8 mm 186 mm FPA Plate scale 11.99 arcsec/pixel Optical elements 5.63 Kg mass Stop FPA size 132 mm 13 mm Field Distortion 3.17% Mechanical design (Bern contribution) Mechanical design (Bern contribution) Based on preliminary tolerance analysis with an overall image quality deterioration by no more than 30% of the nominal value. Mechanical design (Bern contribution) Lines Of Sight Telescopes field Overlap Telescope scale ~ 12.5 arcsec/px -> Telescope Field f=24.9° side Configuration Total field side (2-k)f K= overlapping factor K=1 -> 1 LOS ->Total field side =f K=0-> 4 LOS ->Total field side =2f It is movie time… New “ESTEC-29-Nov” baseline Plate scale of 14..15arcsec/pixel Aperture of full 120mm Coverage on CCD of 132mm in size 800 square degrees of Field of View 90% of EE in 2x2 pixel 15 arcsec/pixel – 6 lenses 394 mm Spectral Range 450 – 1000 m Entrance Pupil Diameter 120 mm F/# 2.06 @ 700 m Field of view 28.64 × 28.64 degree2 225 mm FPA over FPA 129 mm = 786 degree2 2 over FPA 132 mm = 820 degree Image quality 80% EE 2×2 pixel2 90% EE 2.5×2.5 pixel2 Stop Plate scale 15 arcsec/pixel Lens glasses Schott catalogue RadHard Aspheric surfaces Optical elements < 7.5 Kg mass Optimization FPA size 132 mm Field Distortion 4.61% (Preliminary) conclusions New optical design with an additional lens are ready 14..15 arcsec/pixel dilemma?? Optical quality definition?? Which is the “current” baseline?? When can we really freeze the design?? Frozen specifications needed!!!
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