1. The two faces of the METIS Adaptive Optics system Remko Stuik, Stefan Hippler, Andrea Stolte, Bernhard Brandl, Lars Venema, Miska Le Louarn, Matt Kenworthy, Rainer Lenzen, Eric Pantin, Joris Blommaert, Alistair Glasse, Michael Meyer, and the METIS consortium

2. Outline The science & METIS AO System The SCAO system The LTAO system Conclusions 27 May 2013

3. Summary METIS mid-IR imager & Spectrograph 3 rd on ESO Roadmap: ELT-MIR Phase A: –Internal SCAO –External LTAO (ATLAS  ?) Strong consortium –Refining science & requirements –Preparing kick-off –Definition Interfaces Includes LTAO 27 May 2013

4. Instrument Baseline 1. An imager at L/M & N band with an 18˝×18˝ wide FOV. The imager includes: –Coronagraphy at L/M and N-band –Long slit, low-resolution (R ~ 5000) spectroscopy at L/M & N –Polarimetry at N-band [TBC]. 2. An IFU fed, high resolution spectrograph at L/M band –[2.9 – 5.3μm] with a FoV of ≈0.4˝×1.5˝ and –a spectral resolution of R≈100,000. All subsystems work at the diffraction limit –METIS requires AO correction 27 May 2013

5. Science versus AO Requirements The Science Discovery and Characterization of Exoplanets. Circumstellar Disk Structure and Evolution Formation and Evolution of Stars and Star Clusters. Physics and Chemistry of the Solar System. Formation and Evolution of Galaxies. Unique Scientific Opportunities. The AO System  High Contrast/ Low residual jitter  Correction over a larger field of view  Embedded sources  Tracking on moving sources  High sky coverage/ Extended sources  Flexible AO system 27 May 2013

6. The two faces SCAO Excellent on-axis Integrated in METIS –Minimize residual jitter ‘simple’ first light AO BUT: Requires bright GS –Low sky coverage No performance in field –Strong drop towards edge LTAO Wide(r) field performance Accepts fainter GS(s) – Increased sky coverage BUT: Decreased on-axis Separate system – Larger jitter Increased complexity 27 May 2013 Note: Both systems required to reach full potential of METIS

7. SCAO Implementation SCAO internal to METIS –Cold, low (M)IR background Dichroic first optic inside METIS –Cold! –Splits at ~2.5 micron –Full METIS field ~18x18” Large field selector –Full METIS field –Allows or field de-rotation ~40x40 sub-apertures –Reduced complexity IR WFS –Embedded sources –Selex experience Gravity Pyramid WFS –Detector available –But extended sources? 27 May 2013 ELT Focus METIS Entrance Window Dichroic Field Selector Pupil de-rotator ADC?

8. SCAO Simulations Currently running YAO simulations –Specific science cases –Include spiders, segmentation,… –Investigate static speckles But currently limited to AO impact only –Provide input METIS science team Next slide –To do: WFE/vibrations telescope + instrument –Stefan Hippler, Matt Kenworthy & RS 27 May 2013

9. Massive YAO Simulation for the METIS INM 2 Seeing Conditions (0.6 & 0.8”) 4 Zenith angles (0, 30, 45, 60°) 4 Off-axis angles (0, 10, 20, 30°) (18x18”) 9 Star brightnesses (K=7..15) 4 Wavelengths (2.0(WFS), 3.5, 4.7, 10.0 µm) 37 meter, 11.1 central obscuration Spiders + segmentation included 40x40 subapertures, Shack-Hartmann WFS, K-band only(!) ~Paranal atmosphere, Outer scale 25 m, K=13 Sky Background 1 sec integration @ 1000 Hz, 3e- RON, 0.56 throughput to WWFS 27 May 2013

10. SCAO Sky Coverage27 May 2013 Forget getting any sky coverage on random targets

11. LTAO I Phase A: –Facility LTAO: ATLAS Next phase: –Pre-focal station? –Directly attached to METIS? Piggybacking on Harmony LTAO –Relaxed specs  own solution? Several free parameters –LGS locations Trade-off performance, clear LGS path & clear science path –NGS off-axis distance Inside METIS (re-use SCAO)? External WFS? NGS Tomography? –NGS order Determines limiting magnitude Requirement by LTAO system? 27 May 2013

12. LTAO Simulations27 May 2013 2.2 µm3.7 µm10 µm AO Only AO + Telescope Only ESO Octopus Simulations/Miska Le Louarn Best case scenario

13. LGS Constellation ~insensitive to LGS guide star asterism  Easy to provide full clear aperture NGS position within 30”  Simple scheme NGS within METIS FoV  Simple scheme NGS 15-30” outside FoV  Tomography on NGS outside this range Not very sensitive to 2x2 or 1x1 NGS scheme  But might need to sense e.g. focus for LGS Faint NGS possible  Impact sky background TBD  Seems possible to use faint star near Science Target 27 May 2013 Radius to prevent obscuration Internal pick-up METIS V~28V~23 Only photon noise Vmag =20  100 ph/s Sky background optimization J+H+Ks ~31000ph/s/sq”  ~2 e-/s/pixels LGS Constellations NGS off-axis distance NGS brightness

14. Conclusions METIS requires an AO system to meet its science requirements –Requires both SCAO and LTAO [at first light] Reaching the diffraction limit (>60% @ N) relatively easy with a simple AO system –High Strehl, Stable PSF very likely –Can use standard components developed for other AO systems –>93% @ N requires more work/full end-to-end investigation Parallel development of an external LTAO system –Enhancing the sky coverage –Further improving PSF stability in field –Might use internal WFS for Lower Orders and/or NGS tomography Still much work to do –Full integrated modeling of all effects –Verifying input data atmospheric modeling –Cross-coupling of effects –Impact of telescope vibrations, etc.. 27 May 2013