Disruptive technologies to trigger science discoveries

Transcription

1 Disruptive technologies to trigger science discoveries Emmanuel HUGOT Laboratoire d Astrophysique de Marseille EWASS Plenary talk, June 28th, 2017

2 Outline Chapter 0: The Era of Giants Large telescopes and related challenges Chapter I: Stress polished toric mirrors Contribution to the VLT SPHERE planet finder Chapter II: Curved and deformable detectors Focal planes, make them active 2

3 The Era of Giants: challenges ELT instrumentation Science drivers: farthest galaxies, faintest exoworlds,... Focal plane station = Size of a VLT unit (!) VLT SPHERE: 20m 3 E-ELT HARMONI ~100m 3 3

4 The Era of Giants: challenges ELT instrumentation Science drivers: farthest galaxies, faintest exoworlds,... Focal plane station = Size of a VLT unit (!) VLT SPHERE: 20m 3 E-ELT HARMONI ~100m 3 Wish list Cryogenic environment (IR) High throughput & stability High angular resolution PSF uniformity in the field And more: Multiplex Broad wavelenght range Low noise/large formats detectors... Beyond current limitations New paradigms 4

5 Towards efficient instrumentation Collimator: 4 lenses Grating From Cuby inc. Hugot Camera: 6 lenses Conventional spectrograph Length: 2.0 m Only 2 mirrors Volume gain x5 Throughput gain 20% No chromaticity Simplified AIT phase No collimator Camera: 1 freeform(!) Length: 0.6m Grating 5

6 The price to pay F/16 beam 150mm Detector 2k x 2k F/4 beam 1. Extreme freeform shape 10 times higher than state of the art 2. Flat field, large detector Increased optics complexity 6mm deviation Overcome fabrication limits Make them active Curve the focal plane Required optical quality <100nm 6

7 Diameter [m] Telescopes evolution The advent of Active optics NTT: New Technology Telescope The first active telescope Wilson+1991 Active telescopes Active telescopes Refractive Reflective, Monolithic Reflective, Segmented From Bastait, 2010 Year 7

8 FOCUS ON 8

9 Active Optics Stress polishing of the SPHERE toric mirrors in collaboration with the SPHERE consortium ESO press release 2012

10 Exoplanet imaging: VLT-SPHERE High contrast imaging Extreme AO 90% Strehl in H band Three Toric mirrors + Active Optics system SPHERE on the VLT-UT3 Nasmyth platform 41 x 41 actuators Deformable mirror Coronagraph for starlight extinction Contrast Off axis optical design Avoid diffraction effects Beuzit Fusco Dohlen Sauvage Vigan HR 4796A Iota Sgr Crédit ESO 10

11 Exoplanet imaging: VLT-SPHERE Tip Tilt High order deformable mirror Three Toric mirrors + Active Optics system HR 4796A Iota Sgr Crédit ESO 11

12 Exoplanet imaging: VLT-SPHERE Dealing with residual speckles Due to AO, randomly distributed, will average out during a ~ 1 hour exposure Due to static aberrations: will remain in the image plane and limit the high contrast performance 12

13 Exoplanet imaging: VLT-SPHERE Dealing with residual speckles HiF errors MidF errors Tiny static speckles come from optical surface errors Image plane = frequency domain mid frequency errors = performance loss 13

14 HIGH CONTRAST IMAGING & STRESS POLISHING 14

15 Stress polishing principle Step 1: Substrate warping Into the inverse form you want to reach Step 11: Spherical grinding/polishing Using full size tools and Imprint the warping function Step 111: Removal of the loads Get your aspherical surface at rest Gain: High quality off axis surfaces No sub aperture tool marks Perfectly suited for High contrast imaging 15

16 VLT-SPHERE Toric mirrors Three Toric mirrors in the AO common path Toric: Simple combination of a sphere + astigmatism, Astigmatism generation 2 pairs of equal and opposite forces Variation of the radius of curvature in 2 orthogonal directions Basic solution generates radial and angular harmonics

17 Analytical model FEA validations Solve this problem: Hugot et al Applied Optics 2009 Two thickness substrate (external thick ring) get rid of radial harmonics Angular thickness distribution get rid of angular harmonics Topological optimisation: optimise the mechanical warping down to nanometric precision Analytical definition Finite element analysis Interferometric validation Warping ~20µm Residuals <3nm RMS Solve the inverse problem

18 Blanks and warping harness Three substrates: Diameters 174mm, 40mm, 396mm Deformation system: Circular ring attached to the back + 2 micro-screws to warp the system TM1+deformation system TM3 396mm Spherical pitch lap TM1 174mm TM2-40mm

19 Super-polishing results Exquisite results Form errors Ultra-low HF level Sub-nm roughness ~10-20nm RMS ~1-2nm RMS ~5 Angströms Delivered to SPHERE in one spare in 2013

20 Super-polishing results Exquisite results Form errors Ultra-low HF level Sub-nm roughness ~10-20nm RMS ~1-2nm RMS ~5 Angströms Delivered to SPHERE in one spare in 2013 Hugot+2009 (App. Opt.) Hugot+2012 (A&A)

21 Super-polishing results Exquisite results Form errors Ultra-low HF level Sub-nm roughness ~10-20nm RMS ~1-2nm RMS ~5 Angströms Delivered to SPHERE in one spare in 2013 Hugot+2009 (App. Opt.) Hugot+2012 (A&A) BUT

22 Next step: Active Toric Mirror Big issue: ageing of High Order DM Large amount of Cylindrical bending 20 C! Strongly reduces the dynamic of the HODM (~20µm) Evolves with temperature and hygrometry Solution: Install a warping harness on TM3 for cylinder compensation Shape optimization with FEA: the influence function of one actuator generates the required cylinder

23 Next step: Active Toric Mirror Compensation results on SPHERE XAO now fully functional Hugot+2008, Sauvage Lemared Work done with: Sabri Lemared, Anais Bernard, Zalpha Challita, Jean Luc Beuzit, Jean François Sauvage, Anne Costille, Thierry Fusco, Kjetil Dohlen HODM 20 C AO off HODM + TM3@3mic HODM + TM3@10mic AO on Motorization system 94% 1.65µm Installing the active TM3 inside SPHERE On-sky demonstration of the complementarity between active and adaptive systems

24 NASA-STScI / HiCat mirrors HiCat = high contrast STScI Same challenges as on SPHERE, in terms of surface quality Delivery of 3 super-polished off axis mirrors in 2013 Exquisite results too: Only 12nm WFE after 15 optics! O34 O7 O8 LoF WFE [nm] MiF WFE [nm] HiF WFE [nm] Roughness [nm] N Diaye, Soummer

25 NASA-STScI / HiCat mirrors HiCat = high contrast STScI Same challenges as on SPHERE, in terms of surface quality Delivery of 3 super-polished off axis mirrors in 2013 proof Feasibility study 25

26 FOCUS ON 26

27 Curved µbolometer array Curved detectors PhD Delphine DUMAS Post doc Yann GAEREMYNCK PhD Wilfried JAHN PhD Christophe GASCHET PhD Mélanie ROULET Post doc Simona LOMBARDO in collaboration with Dumas, Fendler et al Multi-CMOS curved array Chambion inc. Jahn&Hugot

28 Breaking News: just delivered! 20 Megapixels, 24 x 32mm² full frame VIS curved CMOS sensor Radius: 150mm, Concave Fully functional, in its original packaging 28

29 Optical systems and curved focal planes Comparison between fisheye objectives and monocentric systems Stamenov+2015, Applied Optics 29

30 Flexible focal plane arrays The Fish eye exercise Two optimized optical designs Based on a CANON patent One lab prototype One pre-industrial demonstrator Dramatically increased optical quality up to 50% Save about 30% of optical surfaces Canon Design Flat focal plane 14 lenses 11 materials Chambion, Jahn, Hugot et al 2015 Lab proto LAM/LETI design #1 Concave variable FP 9 lenses 3 materials Patented Pre-indus design proto LAM/LETI design #2 Convex sensor 10 lenses 7 materials 30

31 Flexible focal plane arrays The Fish eye exercise Two optimized optical designs Based on a CANON patent One lab prototype Canon Design Flat focal plane 14 lenses 11 materials One pre-industrial demonstrator Chambion, Jahn, Hugot et al 2015 CAD design interfaced with Canon Camera Lab proto LAM/LETI design #1 Concave variable FP 9 lenses 3 materials Patented Pre-indus design proto LAM/LETI design #2 Convex sensor 10 lenses 7 materials 31

32 MANUFACTURING THE DEFORMABLE CURVED DETECTORS 32

33 Existing solutions Monolithic VIS 4kx4k Iwert ESO + UofA development Mosaic FPA with flat detectors Kepler focal plane Spherical Radius 80 mm Curved µ bolometer array Dumas, Fendler x 256 Spherical Radius 250 mm Aspherical shape Sony, Itonaga+2014 Curved image sensors Microsoft, Guenter+2017 Curved IRCMOS Tekaya, Fendler

34 Flexible focal plane arrays Principle Combine active mirrors and flexible arrays Gain Control the bending of the substrates Reach any curvature before breakage Test performance over a broad range of curvature Simplify manufacturing process? Curved single chip prototype On deformable substrate Ferrari 1998, A&A Variable Curvature mirrors for the VLTI 34

35 Flexible focal plane arrays Extensive simulation on (100)-oriented silicon plates to extract: min. allowable Radius achievable before breakage limit On top and bottom surface of the detectors For different thicknesses Outputs: Confirm previous results Allowed to extract Regions of Interest Other type of simulations on different structures (confidential) 35

36 Performance comparison flat/curved Data sheet Flat Sensor R=150 Curved sensor Conversion coefficient 0,25 DN/e - 0,24 DN/e - 0,22 DN/e - Dark noise 8 e - 9 e - 9 e - Dark current (25 C) 125 e - /s 119 e - /s 169 e - /s * Functional CMOS sensor on 150mm curvature radius Small curvature impact on electro-optical response Full characterization on going at CEA, results to be confirmed next month. Stay tuned! *Extrapolated values Considering +12,5%/ C 36

37 Project-wise roadmap FOCUS ANR program Pre-indus proto Development of prototypes Realization of optical systems ERC program LAM/LETI design #2 Convex variable FP N lenses N materials PhD and Post doc position A 350k CFT to be issued for prototypes realization next year Leverage to structure activity with ESO and ESA? ANR program Ground based demonstrator Schmidt telescope Opportunity to have a psychological impact with an on-sky system 37

38 Agencies ESO directorate of engineering LAM in Oct Working on a super-muse like concept, no optical solution without curved detectors This R&D is identified as a priority ESA roadmap Discussions with ESO direction of engineering GSTP on curved detectors already identified NASA roadmap Curved detectors listed in potential breakthrough technologies in the decadal survey currently ongoing. 38

39 Curved bolometer Rc = 80 mm Curved VIS prototype On deformable substrate Dumas et al 2012 Hugot et al 2016 CURVED DETECTORS soon off-the-shelf, soon on the E-ELT, soon in space? Highly curved VIS CMOS detector Rc = 150mm Curved IRCMOS Rc = 250 mm Gaschet, Jahn, Hugot, Ferrari et al 2017 in prep. Tekaya et al