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MultiConjugate Adaptive Optics from VLTs to ELTs

MultiConjugate Adaptive Optics from VLTs to ELTs. J.-M. Conan(1), B. Neichel(1,2), C. Petit(1), M. Nicolle(1) T. Fusco(1), E. Gendron(2), G. Rousset (3,2,1), P. Jagourel(2), F. Hammer(2) (1) ONERA – DOTA - HRA (2) Observatoire de Paris-Meudon

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MultiConjugate Adaptive Optics from VLTs to ELTs

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  1. MultiConjugate Adaptive Opticsfrom VLTs to ELTs J.-M. Conan(1), B. Neichel(1,2), C. Petit(1), M. Nicolle(1) T. Fusco(1), E. Gendron(2), G. Rousset (3,2,1), P. Jagourel(2), F. Hammer(2) (1) ONERA – DOTA - HRA (2) Observatoire de Paris-Meudon (3) Université Paris 7

  2. Adaptive Optics and Anisoplanatism Effects NAOS Data ; 2,2µm ; Field of View =27’’ ; courtesy D. Rouan Isoplanatic FoV~ 20’’ Isoplanatic FoV ~ 2’’ Standard AO corrected FoV is very limited

  3. MCAO allows wide FoV correction Specificities: • multi-guide-star wavefront sensing • multi-DM correction of the turbulent volume Expected performance: few arcmin diffraction limited correction for NIR VLT obs. with a few GSs and a few DMs Principle of MultiConjugate AO [MCAO]

  4. FoV No Correction: Seeing limited GLAO: reduced apparent seeing « Ground Layer » Adaptive Optics [GLAO] GLAO: • multi-GS WFS • single ground DM correcting average perturbation ~ near ground turbulence Expected performance: single Ground DM seeing improved and stabilized in very large FoV gain ~2 in 10 arcmin for NIR VLT obs.

  5. MultiObject AO [MOAO] – Falcon study Extra-galactic 3D spectrocopy near-diffraction limited correction on tens of faint/tiny galaxies in very large FoV MOAO: • specific correction/DM per galaxy • multi-GS WFS Expected Performance: Falcon: H band VLT obs. in 25’ FoV • 60 GS for WFS • 15 to 20 IFU on galaxies with 40% coupling in 250mas res. elts see Gendron et al., C. R. Phys., 6, 2005

  6. Outline • Key Features/Issues in MCAO • Multi-GS wavefront sensing • choice of the concept (Star/Layer Oriented, MFoV…) • Natural/Laser GS related to sky-coverage consideration [M. Nicolle et al., JOSA Aaccepted; T. Fusco et al., MNRASaccepted] • Correction optimisation in FoV of interest ≠ GS positions • Reconstruction of turbulent volume from WFS data (tomographic rec.) • multi-DM control • Current VLT MCAO/GLAO projects • MOAO for extra-galactic observations: from VLTs (8-10m) to ELTs (20 to 60m)

  7. Simplified Experimental Configuration : Off-Axis AO On axis pupil Off axis pupil metapupil DM WFS • Optimal Control: • reconstruction of phase in layer(s) • iterative Kalman filter • adequate projection onto DM(s) 1 turbulent layer in altitude 1 on axis GS for WFS 1 off axis star of interest

  8. AO Bench at ONERA : BOA Wave Front Sensor (Shack-Hartman 8*8) Deformable mirror SAM (9*9) Imaging camera (Princeton - 512) Turbulent phase screen Sources (2 stars) : fibered laser diode

  9. First Experimental Demonstration of Off-Axis AO C. Petit et al., C. R. Physique, 6, 2005 On-Axis Star Off-Axis Star collaboration with L2TI-Villetaneuse-Paris 13 and ShaktiWare

  10. Planned VLT Systems and Demonstrators 1/2 • 8m-VLT MAD MCAO demonstrator [ESO-Arcetri] first light end 2006 • 2’ FoV NIR imaging : 5 to 8 NGS, 2 DM (~60 act. each), • 8m-GEMINI South MCAO [Gemini] first light 2007 • 2’ FoV NIR imaging : 5 Na-LGS + 3 TT-NGS, 3 DM (~200 act. each), • 2x8m-LBT LINC-NIRVANA MCAO [MaxPlanck-Arcetri] • up to 2’ FoV NIR interometric-imaging : 12 NGS, 672 act. DSM +1 or 2 DMs (~300act.) • 8m-VLT GRAAL GLAO for HAWK-I [ESO] first light 2012 • 10’ FoV for NIR imaging : 4 Na-LGS + 1 TT-NGS, 1170 act. DSM • 8m-VLT GALACSI GLAO for MUSE [ESO] first light 2012 • 3’’ to 2’ FoV for Vis. spectro-imaging : 4 Na-LGS + 1 TT-NGS, 1170 act. DSM

  11. Planned VLT Systems and Demonstrators 2/2 • Solar MCAO: • KIS (80cm-VTT, future 1.5m-GregorTel) • NSO (70cm-DTT, future 4m-ATST) • Laboratory demonstrators, among others: • Sesame at Obs.-Meudon – multi-GS sigle-DM configuration available • Homer at Onera – currently in design phase, 2-DM config. planned for 2007

  12. MultiObject AO [MOAO] – Falcon study Extra-galactic 3D spectrocopy near-diffraction limited correction on tens of faint/tiny galaxies in very large FoV MOAO: • specific correction/DM per galaxy • multi-GS WFS Expected Performance: Falcon: H band VLT obs. in 25’ FoV • 60 GS for WFS • 15 to 20 IFU on galaxies with 40% coupling in 250mas res. elts see Gendron et al., C. R. Phys., 6, 2005

  13. MOAO VLT versus ELT specifications • 10 m class specifications • 0.5 < Z < 2 – 3 • galaxy size ~ 1 arcsec • R ~ 10000 • EE in H : 40% in 250 mas ~ 6 λ/D • 15 to 20 objects • 25’ FoV • 40 m class specifications • Z up to 5 – 8 • galaxy size 0.15 arcsec • R ~ 10000 • EE in H : 40% ?? in 50 mas ?? • 10 objects • 10’ FoV Falcon design study: • 60 GS for WFS • 15 to 20 IFU on galaxies with ~100 act. correction • sky-coverage ~ 50% at b=30° see Gendron et al., C. R. Phys., 6, 2005 • Preliminary hints on design choices: • specs versus NGS/LGS choice • MOAO compared to GLAO

  14. MOAO: impact of specifications 42 m telescope ideal case: noise + fitting, no anisoplanatism… , nact > 5000 LGS scientific specification ? NGS H band Specs strong impact on limiting magnitude

  15. Laser MOAO GLAO MOAO design issues: LGS/NGS , comparison with GLAO • GLAO far below specs • MOAO with GSs in 2 arcmin FoV meets specs • Ideal LGS here: no elongation/cone effect • for VERY large telescopes TT not an issue • but still is for 40m-tel, 50mas resel, 50m Lo Ensquared Energy in 50 mas Results strongly dependent on turbulence parameters: seeing, Cn2 and Lo profiles collab. with LUAN-Nice see B. Neichel et al., IAU Le Cap, 2005 & SPIE Orlando 2006

  16. MCAO: Current Status • MCAO/GLAO/MOAO Concepts well established: theorerical studies, numerical simulations • Laboratory tests are under progress at ESO, Obs. Meudon and Onera • 10m class telescope intrumentation programmes are launched • Next step: MCAO for ELTs • precise the scientific specifications and associated high level technical specs • pursue design studies for MCAO/GLAO/MOAO and specify key components (DMs, WFS, LGS, control…) • strong MOAO effort in France: ESO study MOMFIS, ELT-design-study WFSPEC • turbulence inputs are required: Paranal campaign planned by LUAN-ESO in collab. Onera • To know more on MCAO: Special Issue Comptes Rendus de l’Académie des Sciences, Physique Series, Dec. 2005 [articles available on ScienceDirect] • all this started with Come-On and with the VLT programme under the impulse of Pierre Léna • personnaly: Pierre helped me set up in 1990 a pre-doc at NSO-SacPeak • followed by PhD on AO co-supervised by Pierre and Gérard Rousset

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