Des MOEMS dans les instruments astronomiques du futur

Transcription

1 Des MOEMS dans les instruments astronomiques du futur Frederic Zamkotsian 1, Patrick Lanzoni 1, Michael Canonica 2, Wilfried Noell 2, Laurent Marchand 3 Laboratoire d Astrophysique de Marseille, France EPFL, Suisse Agence Spatiale Européenne, Pays-Bas

2 Instrumental needs Instrumental needs using micro-opto-electro-mechanical systems (MOEMS) Phase Wavefront control - Deformable mirrors Intensity Object selection - Programmable slits Wavelength Spectral domain application - Programmable gratings

3 Exoplanets

4 Adaptive Optics Principle Corrected plane wave Perturbated wavefront, from the telescope Wavefront sensor (Shack-Hartmann, curvature) Deformable mirror (piezo, bimorph) Computer

5 NAOS: PSF recovery

6 Deformable mirrors Mirrors with classical technology Piezo and magnetic actuators Few 100 actuators Inter-actuator spacing 5mm Micro-deformable mirrors (MDM) Electrostatic force Up to actuators (Extremely Large Telescope) Inter-actuator spacing 500µm-1mm MDM with membrane MDM with attached actuators

7 Electrostatic MOEMS deformable mirror Actuator Mirror Design Realization Characterization Characterization Realization Design Actuators + Mirror α Design Realization Characterization Y (µm) MDM prototype + X (µm)

8 Bulk micro-machined continuous MDM Mirror Surface STRUCTURE 37 actuators for 15 mm optical aperture 9 µm deflection with 255 V driving voltage 1 khz bandwidth Substrate Electrodes l h (Vdovin, Delft University, Netherlands) Advantages: Disadvantages: - Continuous membrane - Good quality of the mirror surface - Large deflection - Good bandwidth - Fragile suspended membrane - Large inter-actuator coupling - Limited size of the optical aperture - Limited number of actuators (high order perturbation correction is limited)

9 OKO mirror Actuator at maximum voltage (one by one) Actuators with ramp voltage (all) OKO #1: Vmax = 160V OKO #2: Vmax = 220V

10 Segmented micro-machined MDM STRUCTURE Mirror Surface Flexure arms 128 actuators and 203 µm inter-actuator spacing 0.6 µm deflection with 15 V driving voltage 80 % fill factor Substrate Actuators l h (Cowan, Air Force Research Lab., USA) Advantages: Disadvantages: - Independent actuators - Unlimited number of actuators (high order perturbation correction) - Good quality of the mirror surface - Low driving voltage - No inter-actuator coupling - Segmented mirror surface (diffraction effects) - Small deflection - Fill factor < 100 %

11 Surface micro-machined continuous MDM STRUCTURE Mirror Surface Anchoring post 140 / 4096 actuators, 300 µm inter-act. spacing 2-6 µm deflection with 250 V driving voltage 7 khz bandwidth Substrate Actuators l h (Bifano, Boston University, USA) Advantages: Disadvantages: - Continuous membrane - Unlimited number of actuators (high order perturbation correction) - Limited inter-actuator coupling (10 %) - Good bandwidth - Print-through effect - Large driving voltage - Coating stress

12 MMD en boucle ouverte L Optique Adaptative Multi-Objets (MOAO) a besoin de miroirs déformables en boucle ouverte L actionnement électrostatique est hautement non linéaire F e = 2 ε 0 SV t 2(( g + ) w) ε r 2 Electronique dédiée de linéarisation 400 Déplacements (nm) Attendue_fit ChRep Obtenue_mesures différence Tensions (V) Différence (nm) Actual motion (nm) Déviation: 3.5nm Command (nm)

13 Universe expansion

14 EUCLID EUCLID Mission for ESA Cosmic Vision Program Looking for Dark Energy and Dark Matter EUCLID - NIS Near Infrared Spectrograph Measurement red-shifts of galaxies Huge sample of millions galaxies Dark Energy 73% E NIS Matter 4% Dark Matter 23% DMD Multi-Object Spectrograph option based on DMD DMD 2048x1080 Micromirrors made by TI DMD space evaluation (Visitech - LAM)

15 Multi-Object Spectroscopy (MOS) Field of view Measured spectra Space Telescope Light trap Micro-mirror array in the telescope focal plane Spectrometer CCD camera

16 DMD 2048 x 1080 micromirrors DMD chip 2048 x 1080 micromirrors (13.68 µm pitch) Designed for use at ambient temperature, at atmospheric pressure and to be actuated several thousand times per second, DMD operation in EUCLID Vacuum, -40 C, static patterns for 1500s Space evaluation: under vacuum, at cold temperature, life test, thermal cycling, physical analysis, radiations, vibration & shock No showstopper

17 MIRA: une matrice de micro-miroirs européenne

18 MIRA: the requirements Initial list of requirements Mirror size of 100 x 200 µm 2 Individual addressing of the micromirrors High contrast of at least 1000:1 20 mechanical tilt angle Uniform tilt angle over the whole array Fill factor of more than 90% (if possible >95% in one direction Wavelength range from visible to infrared Optically flat mirrors in operation < λ/20 with λ = 1 µm Cryogenic operating temperature (<100K, 30K goal)

19 MIRA: the principle Concept and design a) Rest position b) 1 st tilting c) Stopper & 2 nd tilting d) Electrostatic latching electrode fix-points mirror

20 MIRA: the realization

21 MIRA: the realization 100x200 µm 2 mirrors

22 MIRA: the realization 2048 mirrors (64 x 32)

23 MIRA: the realization 2048 mirrors (64 x 32)

24 Interferometric bench Bench in operation since 2004 Michelson interferometer scheme Resolution XY: 3 µm Resolution Z: < 1 nm 0,1nm -0,1nm

25 MIRA: the performances Performances Mirror size of 100 x 200 µm 2 20 mechanical tilt angle Applied voltage around or below 100V Uniform tilt angle over the whole array Fill factor of more than 85% (97% in long-slit direction) Optically flat mirrors in operation (< 10 nm PtV) Cryogenic operation Individual addressing of the micromirrors (line-column addressing scheme)

26 Cryogenic test Specific cryo chamber developped, compatible with our interferometric bench Vacuum 10-6 mbar Cryogenic temperatures

27 Cryogenic test Specific cryo chamber developped, compatible with our interferometric bench Vacuum 10-6 mbar Cryogenic temperatures

28 Cryogenic test 162K 0 V

29 Cryogenic test 162K 148 V

30 MIRA: the line-column addressing -10V -30V -30V - 80V 80V 20V

31 MIRA: the future Short-term future Large array wire bonding Large array optical characterization Large array cryo testing at < 100K Mid- and long-term future Yield issue Even larger arrays Cryo testing at < 30K (facility available summer 2012) Integrated electronics

32 Intégration de l électronique Wafer électronique (ASIC) Interposer Stack de wafers Vias MIRA: à venir Electronique compatible en environnement spatial (vide, cryo, radiations) Micromirror Interposer Low voltage coupled with High voltage ASIC

33 Des MOS à base de MOEMS

34 Des MOEMS pour l astronomie Utilisation des MOEMS en spectroscopie multi-objets, en optique adaptative et sur des spectrographes programmables Développements européens spécifiques en cours, comme le projet MIRA de fentes programmables en réflexion Les MOEMS développés pour l astronomie peuvent aussi avoir des applications dans d autres domaines (physique, biologie )