MultiConjugate Adaptive Optics from VLTs to ELTs

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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

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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
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Principle of MultiConjugate AO MCAO
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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.

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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

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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 A accepted T.
  Fusco et al., MNRAS accepted
• 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)

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Differents concepts dASO multi-direction
DM 2
DM 1
Pupil
COMMAND
1 WFS / GS
STAR ORIENTED
LO plus efficace en terme de bruit de détection
mais sensible aux écarts de flux entre EG

• Choix de la technique danalyse en fonction
• des spécifications (champ, performance)?

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Optimal Tomographic Reconstruction based on
Kalman Filter

• AO/MCAO System
• closed loop with delay
• WFS interaction matrix D
• DM influence function matrix N
• Phase expanded on modes
• Closed-loop measurement equation
• Global control problem
• find
  minimizing the stochastic
  criterion
• Principle of separation
• optimal estimation of the turbulent volume
• find
  minimizing
• Deterministic projection onto mirror space

u
Kalman Filtering
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Simplified Experimental Configuration Off-Axis
AO

• 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
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AO Bench at ONERA BOA
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First Experimental Demonstration of Off-Axis AO
On-Axis Star Off-Axis Star
collaboration with L2TI-Villetaneuse-Paris 13
and ShaktiWare
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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

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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

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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

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MOAO VLT versus ELT specifications

• 10 m class specifications
• 0.5 lt Z lt 2 3
• galaxy size 1 arcsec
• R 10000
• EE in H 40 in 250 mas 6 ?/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 b30
• see Gendron et al., C. R. Phys., 6, 2005

• Preliminary hints on design choices
• specs versus NGS/LGS choice
• MOAO compared to GLAO

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MOAO impact of specifications
42 m telescope ideal case noise fitting, no
anisoplanatism , nact gt 5000
LGS
scientific specification ?
NGS
H band
Specs strong impact on limiting
magnitude
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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
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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 lAcadémie 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