AO for ELT – Paris, June 2009 MAORY Multi conjugate Adaptive Optics RelaY for the E-ELT Emiliano Diolaiti (INAF–Osservatorio Astronomico di Bologna) On behalf of the MAORY Consortium INAF + University of Bologna ONERA ESO

AO for ELT – Paris, June Concept  Corrected field of view –Central 53"x53" unvignetted for MICADO –Outer field Ø=160" for Natural Guide Star search and other instruments  Wavefront sensing –6 Sodium Laser Guide Stars for high-order wavefront measurement –3 Natural Guide Stars for low-order and windshake measurement –1 Natural Guide Star used as high-order reference WFS  Wavefront correction –Telescope M4 + M5 –2 post-focal deformable mirrors –Simplified option with 1 post-focal DM and reduced outer field under study

AO for ELT – Paris, June Two ports 1) gravity invariant w/ field derotation 2) vertical w/o field derotation Preliminary bench size: 6335 mm  6755 mm Preliminary mass estimate: 13 t See poster by Italo Foppiani

AO for ELT – Paris, June Optical design M7 R = 10 m K = D = 1 m M9 R = 9.8 m K = D = 1.1 m M11 R = 9,.8 m K = D = 0.9 m M13 R = 10 m K = D = 0.9 m M13 R = 10 m K = D = 0.9 m M8 D = 370 ~45 act/D M10 Flat D = 0.9 m M12 D = 414 mm ~52 act./D Field Ø160" WFE  25 nm Distortion < 0.1% Field curvature R = 1.3m To LGS channel

AO for ELT – Paris, June LGS optics and aberrations Dichroic L1 D = 800 mm L2 D = 700 mm L3 D = 580 mm L4 D = 460 mm 200 km80 km 350 mm  Design features –All lenses made of BK7, spherical surfaces (with wedge) –Output focus F/5, telecentric  Image quality –LGS spot FWHM  0.17 arcsec (LGS image through atmosphere  1.5 arcsec) –RMS WFE  2.6 (average for 6 LGS)  SH WFS slope offset  0.5 arcsec  Solutions to LGS aberrations –Correcting optics (likely not static) in each LGS probe –Handled as slope offset  Pupil stabilization and jitter control to be implemented in each LGS probe

AO for ELT – Paris, June Thermal emission Telescope emissivity = 10% Sky brightness K = 13 mag/arcsec 2 Emissivity of MAORY optics = 1% per surface (left) or 2% per surface (right) No cooling for T < 30  CNo cooling for T < 16  C Requirement on thermal emission < 50% (telescope + K Requirement seems to be fulfilled at ambient temperature Paranal average temperature year 2003 (highest average ): T = (13.1  2.6)  C (from

AO for ELT – Paris, June Pupil rotations  Baseline –LGS fixed wrt telescope –Post-focal DMs derotated by 60° (  30°) –LGS WFS probes derotated by 60° (  30°)  How do things move in this scheme? –All DMs (M4 and post-focal) appear fixed wrt LGS WFS –Pupil rotates wrt post-focal NGS WFS at maximum speed ~15/s for a Zenith angle of 1°. Reconstruction matrix of low order modal loop to be updated every 10s –High order loop reconstruction matrix (25GB of data) must be updated every 140s (LGS footprint variation)  Alternatives –Post-focal DMs cannot be derotated  reconstruction matrix to be updated every 35s –LGS fixed wrt sky  reconstruction matrix to be updated every 0.5s

AO for ELT – Paris, June LGS Wavefront Sensor 0.75 "/pixel 1.0 "/pixel 1.5 "/pixel Weighted Center of Gravity Photons / subap = 500, RON = 3 Subaperture FoV = 15"  15" 0.75 "/pixel 1.0 "/pixel 1.5 "/pixel Non linearity WCoG vs. Quad-cell  Evaluation of algorithms performance for SH WFS –WFS noise –Impact of Sodium profile –LGS aberrations  Alternative WFS –Pyramid (smaller detectors) –Dynamic refocus (by segmented mirrors on sub-pupils?) Poster by Matteo Lombini

AO for ELT – Paris, June Focus reconstruction scheme Sodium focus sequence on 42 m aperture  Requires NGS reference 6 LGS measure atmospheric + Sodium focus  Used to “predict” focus in direction of NGS  Comparison of predicted NGS focus with actual focus gives Sodium term F(θ 1 ) + Na F(θ 2 ) + Na F(θ 3 ) + Na F(θ 4 ) + Na F(θ 5 ) + Na F(θ 6 ) + Na F(θ)

AO for ELT – Paris, June NGS Wavefront Sensor Target WFE = 100 nm (3 NGS)  4 mas residual jitter per NGS NGS measured in IR benefit from high-order loop correction Baseline H band Windshake is the most challenging issue for tip-tilt. After feedback on telescope main axes a residual jitter ~0.3 RMS is expected. Making use of a predictive control filter (like Kalman) it may be drastically reduced exploiting its high temporal correlation (low frequency components) 4-5 mas/pixel, 1"  1" FoV  at least 256  256 pixels detector required. This is 2  the foreseen high speed IR sensor by Teledyne (128  128, 5e - J. Beletic, SPIE 2008 Marseille) T = 5 ms

AO for ELT – Paris, June MCAO tomography WFS1WFS2WFS3 More details by Jean-Marc Conan and Clélia Robert  Tomography performed by –6 LGS, launched from M1 edge, kept fixed with telescope to relax requirements on RTC. LGS FoV = 2' –3 NGS for low-orders reconstruction  Star oriented architecture

AO for ELT – Paris, June Error sources ItemRMS WFE MCAO (High order)255 nm Generalized fitting + tomography232 nm LGS WFS noise77 nm Generalized aliasing41 nm Temporal error60 nm NGS WFS100 nm NGS WFS noise and time delay100 nm Implementation errors140 nm Optics (including non-common path errors) Deformable mirrors AO control Sodium layer Atmosphere TOTAL308 nm Current PSF estimates include MCAO error budget Other error sources included in Strehl Ratio and Encircled Energy End-to-end simulations ready soon Estimated by “Fourier” code + cone effect degradation factor Input to NGS WFS design and sky coverage estimation Top level allocations More details on simulations by Cyril Petit

AO for ELT – Paris, June Strehl Ratio NGS search field

AO for ELT – Paris, June Encircled Energy (0.8" seeing) 500 mas 200 mas 75 mas 50 mas

AO for ELT – Paris, June Performance & Sky coverage µm Strehl Ratio % K s (2.16 µm) H (1.65 µm) J (1.215 µm) Y (1.021 µm) I (0.9 µm) 0.8" " Nominal average performance over MICADO field of view (53"  53") µm Minimum field-averaged Strehl RatioProbability K s (2.16 µm) H (1.65 µm) J (1.215 µm) Y (1.021 µm) I (0.9 µm) 0.8" % % % 0.6" % % % Sky coverage at North Galactic Pole (L 0 = 25m, windshake included) 3 NGS (2 Tip-Tilt, 1 Tip-Tilt & Focus) measured at H band, NGS search field Ø = 2.5‘ Sky cov. estimated by Monte Carlo simulations of asterisms based on TRILEGAL code

AO for ELT – Paris, June PSF modeling for scientific analysis  AiryHexagonal MoffatMoffat Simulated PSF DIFFRACTIONFITTING ERRORS, UNSEEN MODESSEEING Model components PSF model Strehl Ratio  0.6 Image size = 2.7"

AO for ELT – Paris, June Acknlowledgment The activities outlined in this talk were partially funded by the European Community under the following grants: –Framework Programme 6, ELT Design Study, contract No –Framework Programme 7, Preparing for the Construction of the European Extremely Large Telescope, contract No INFRA