Getting the most out of mid-IR on the E-ELT with the METIS Adaptive Optics system
R. Stuik, S. Hippler, A. Stolte, B. Brandl
Leiden Observatory, Leiden University; Max Planck Institute for Astronomy, Heidelberg; Argelander Institut für Astronomie Universität Bonn; Leiden Observatory, Leiden University
The Mid-infrared E-ELT Imager and Spectrometer (METIS) will bring unprecedented resolution and sensitivity for the mid-infrared to the European Extremely Large Telescope (E-ELT). An adaptive optics system is required to get the most out of METIS both for achieving the resolution as well as the sensitivity and to be competitive and complementary to space missions. Due to the longer wavelength, the complexity of the AO system is significantly reduced, both in required speed as well as order of the AO system, as compared to other E-ELT instruments operating at visible and near-IR wavelengths, but for METIS on the E-ELT, the complexity is still comparable to the high-order AO systems currently coming on-line on the 8-10 meter class telescopes.
Adaptive Optics has been demonstrated to deliver consistently Strehl Ratios exceeding 95% on 6-8 meter class telescopes at 10 microns, and similar performance is expected for METIS on the E-ELT. But to provide a reliable system on the E-ELT, several effects which have a minor impact on 6-8 meter class telescopes will need to be investigated for their impact on METIS AO. Refractivity effects and atmospheric composition variations have the potential of significantly decreasing the performance of METIS AO, while operation in a complex operational environment given by both METIS as well as the E-ELT will make the actual implementation of METIS AO non-trivial.
In this paper we describe the scientific requirements on the METIS AO system, the trade-off of possible solutions to reach the requirements and expected performance of the METIS AO system on the E-ELT.