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

Outline

The science & METIS AO SystemThe SCAO systemThe LTAO system

Conclusions

27 May 2013

Summary

• METIS• mid-IR imager & Spectrograph• 3rd on ESO Roadmap: ELT-MIR• Phase A:

– Internal SCAO– External LTAO

(ATLAS ?)

• Strong consortium– Refining science &

requirements– Preparing kick-off– Definition Interfaces

• Includes LTAO

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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

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 SystemHigh Contrast/Low residual jitter

Correction over a larger field of viewEmbedded sources

Tracking on moving sourcesHigh sky coverage/Extended sourcesFlexible AO system

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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

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Note: Both systems required to reach full potential of METIS

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?

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ELT Focus

METIS Entrance Window

Dichroic

Field Selector

Pupil de-rotator

ADC?

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

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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

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0 10 20 30 0 10 20 30 0 10 20 30 0 10 20 30K=7 0.90 0.85 0.76 0.66 0.90 0.85 0.75 0.64 0.90 0.85 0.77 0.66 0.88 0.81 0.69 0.57K=8 0.89 0.85 0.73 0.64 0.89 0.85 0.75 0.62 0.89 0.85 0.76 0.62 0.88 0.81 0.69 0.59K=9 0.88 0.83 0.74 0.65 0.88 0.83 0.73 0.60 0.88 0.84 0.74 0.65 0.87 0.80 0.68 0.54K=10 0.83 0.80 0.69 0.59 0.84 0.79 0.71 0.62 0.83 0.79 0.71 0.61 0.81 0.76 0.63 0.53K=11 0.73 0.69 0.61 0.51 0.72 0.69 0.61 0.53 0.72 0.70 0.61 0.52 0.71 0.66 0.55 0.49K=12 0.49 0.48 0.43 0.39 0.49 0.48 0.44 0.39 0.48 0.48 0.43 0.38 0.48 0.47 0.39 0.31K=13 0.13 0.16 0.16 0.11 0.13 0.16 0.15 0.14 0.17 0.17 0.15 0.13 0.15 0.16 0.13 0.12K=14 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.02 0.01 0.01K=15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00K=7 0.84 0.77 0.61 0.48 0.84 0.77 0.65 0.53 0.84 0.77 0.61 0.49 0.82 0.73 0.53 0.43K=8 0.84 0.76 0.65 0.51 0.83 0.75 0.63 0.48 0.83 0.77 0.63 0.51 0.81 0.71 0.51 0.39K=9 0.82 0.76 0.59 0.47 0.82 0.76 0.62 0.47 0.82 0.75 0.60 0.48 0.80 0.70 0.55 0.41K=10 0.77 0.71 0.59 0.49 0.77 0.72 0.57 0.45 0.77 0.71 0.59 0.46 0.75 0.65 0.51 0.38K=11 0.66 0.61 0.49 0.40 0.66 0.62 0.52 0.38 0.65 0.61 0.51 0.41 0.64 0.59 0.43 0.28K=12 0.43 0.40 0.35 0.28 0.43 0.42 0.34 0.27 0.42 0.42 0.35 0.28 0.39 0.38 0.29 0.24K=13 0.12 0.13 0.11 0.10 0.11 0.12 0.11 0.09 0.11 0.13 0.11 0.08 0.12 0.11 0.10 0.08K=14 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01K=15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

0.6"

0.8"

0 30Zenith AngleField Angle

Strehl45 60

SCAO Sky Coverage27 May 2013

Sky Coverage

Limiting Magnitude(I) Sky Coverage

Limiting Magnitude(I)

3.5 um Requirement (SR =0.60)

Galactic Equator (|l| < 5°)

0.104

13.2 Intermediate Latitudes (-35° < l < -25°) 0.012

Galactic Pole (l < -80°) 0.003

All sky average (-90° < l < 90°) 0.025

10 um Goal (SR = 0.95) Requirement (SR =0.93)

Galactic Equator (|l| < 5°) 0.073

12.7

0.130

13.5 Intermediate Latitudes (-35° < l < -25°) 0.008 0.015

Galactic Pole (l < -80°) 0.002 0.004

All sky average (-90° < l < 90°) 0.017 0.032

Forget getting any sky coverage on random targets

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?

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LTAO Simulations27 May 2013

2.2 µm 3.7 µm 10 µm

AO Only

AO + Telescope OnlyESO Octopus Simulations/Miska Le Louarn

Best case scenario

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

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Radius to prevent obscuration

Internal pick-up METIS

V~28 V~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 distanceNGS brightness

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