Adaptive Optics With Segmented Deformable Bimorph Mirrors

Transcription

1 Adaptive Optics With Segmented Deformable Bimorph Mirrors Gonçalo N. M. C. Rodrigues Active Structures Laboratory, ULB, Brussels, Belgium February 26, 2010

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4 Astronomy Without Telescopes

5 The Telescope Hans Lippershey, 1608 Moons of Jupiter Galileo Galilei, 1609 Phases of Venus

6 Reflective Telescopes Isaac Newton, 1668 Chromatic Aberration

7 Atmospheric Turbulence The only remedy is a most serene and quiet air, such as may perhaps be found on the tops of the highest mountains...

8 Mount Wilson Ø = 2.5 m Little Sombrero

9 Saturated Resolution α = λ D

10 Space Astronomy Hubble Space Telescope, Ø = 2.4 m, 1990 Little Sombrero

11 James-Webb Space Telescope Ø= 4.5 m Ø= 6.5 m

12 Satellite Spotting Xinetics Deformable Mirrors ISS and Shuttle, 2007 LACROSS Spy Satellites

13 Adaptive Optics in Astronomy [Source: Claire Max]

14 Adaptive Optics [Source: Egner 2006]

15 Laser Guide Stars [Source: Egner 2006]

16 Very Large Telescopes Keck, Ø = 10 m Uranus by Hubble Space Telescope 1500 M$ VLT, Ø = 8.2 m Uranus by Keck Adaptive Optics 100 M$ [Source: Claire Max]

17 Primary Mirrors Lightweighted Monolithic Mirror Monolithic mirror with discrete linear actuators Segmented Mirror [Source: E. M. Flint (Mevicon Inc.), 2003]

18 Flexible Telescopes VLT, Ø = 8.2 m

19 Segmented Mirrors 6 Edge sensors 3 Position actuators

20 Active Optics 5 mm 5 µm [Adapted from: G.Z. Angeli, M.K. Cho & M.S. Whorton, 2003]

21 Evolution of M1 Space Telescopes HST 2.6m Herschel 3.5m JWST 6.5m (2014?) Ground Based Telescopes TMT 30m (2018?) E-ELT 42m (2018?) VLT 8m Keck 10m

22 Scaling Adaptive Optics Number of Actuators Required vs. D M1 Δx Δϕ = 2π λ

23 Radio Telescopes

24 Current Telescopes Number of Actuators Required vs. D M1 VLT 8 m Keck 10 m

25 Piston Actuated Deformable Mirrors Piezo-Stacked SAM1377 [Source: CILAS] Voice-Coil Electrostatic MEMS LBT AS 672 [Source: Fraunhofer]

26 Extremely Large Telescopes E-ELT, 2018 Number of Actuators Required vs. D M1 Ø = 42 m

27 Bimorph Mirrors BIM60 f 1 t 2 D ap mm BIM188 [Source: CILAS] W max E max f 1 d 31

28 Deformable Mirrors for ELTs M4AU M 1 M 2 M m [Source: ESO] M 3 [Source: Cullum 2008] Piezostacked Voice-coil Optical plate Actuator array, #8000 Base plate [Source: CILAS] [Source: Gallieni et al 2009]

29 Scalable Bimorph Mirrors

30 Screen Printed Silicon Mirrors Common mass electrode 80 μm PZT array (green) PZT array sintered Independent top electrodes

31 Scalable Silicon Bimorph Mirrors - Price

32 Prototype of Screen Printed Silicon Mirror 91 actuators

33 Zernike Polynomials

34 Mirror Morphing - FEA

35 Least Square Shape Control Interaction Matrix: T V U D Σ = Singular Value Decomposition: Truncated Pseudo-Inverse: T U V D 1 + Σ = > = ζ σ ζ σ σ σ i i i i 0,, 1/ 1 s = D v Pseudo-inverse: 0 s D v + = Dv s ε = Square Error:

36 Generation of Zernike Mode

37 Generation of Turbulent Screen

38 Experimental Bench Shack-Hartmann 101 x 101 micro-lenses Telescope Voltage Amplifiers Bimorph Mirror

39 Closed-Loop Experimental Results Defocus Astigmatism Tetrafoil 5 μm 4.5 μm 3 μm 140 V 80 V Requested Mode 20 V controlled modes 35 3 Z i

40 Open-Loop Experimental Results Numerical Simulation Experimental Results 5.4 μm 4.9 μm 3.6 μm 2.8 μm Defocus Astigmatism Trefoil Tetrafoil

41 Morphing Segmented Bimorph Mirrors

42 Morphing Continuity Between Segments Electrodes at Edge Mirror Shape

43 3 Segment Demonstrator of Concept

44 Hexagonal Bimorph Mirrors

45 Rigid Body Actuation

46 Voltage Amplification and Connectics

47 Conclusions Successful relative shape control of silicon bimorph mirrors Good Test vs. Analysis correlation Continuous morphing of assembly demonstrated by simulation Open Challenges Correction of permanent shape induced during production Segment co-phasing

48 André Preumont All ASL colleagues Renaud Bastaits Mihaita Horodinca Ioan Burda ULB: Alain Weymeersch Pierre Galland Commité d Accompagnement: Frank Dubois Yvan Stockman CSL: Steve Roose Fraunhofer-IKTS: Andreas Schönecker Sylvia Gebhardt Stephan Uhlig UTC: Pierre Villon Micromega Dynamics: Jean-Philipe Verschueren Thales-Alenia: Arnaud Liotard Lambda-X: Kris de Coninck Xavier Hutsebaut Luc Joannes Acknowledgments Carlos, Herdis, Fausto Ana, Rui and Julián Miguel, Ana, Mª José, Juviano, Nuno Family Mom and Dad Clóvis Verónica