MOAO design, specificities and performance for EAGLE, the high resolution multi-object spectrograph for the E-ELT


T. Fusco(1), G. Rousset(2), J.-G. Cuby(3), R. Myers(4), H. Schnetler(5), P. Jagourel(6) and the EAGLE team


(1) ONERA (2) Observatoire de Paris – LESIA (3) Observatoire de Marseille – LAM (4) University of Durham (5) UK-ATC (6) Observatoire de Paris – GEPI


EAGLE is a wide-field multi IFU near-infrared (NIR) (IZ, YJ, H and K) spectrograph for use on the European Extremely Large Telescope (E-ELT). The instrument shall be capable of observing twenty science targets simultaneously and the atmospheric disturbances will be corrected by making use of an Adaptive Optics (AO) system.

The wide field, highly specialised AO system is the heart of the EAGLE concept. Due to the large field-of-view, a multi-object adaptive optics (MOAO) system will control the GLAO corrected field of the ELT (M4 and M5) with an additional Deformable Mirror in each channel of EAGLE. Six Laser Guide Stars and up to five Natural Guide Stars will be used to efficiently perform a tomographic analysis of the turbulent volume.

Based on the EAGLE MOAO system requirements, we have optimized the MOAO concept, and derive a residual wavefront error breakdown as part of the Phase A system design. The critical system choices are analysed and justified. Specific MOAO items are highlighted and it is shown that most of them allow us to reduce the overall system complexity with respect to some other wide field AO concepts. Finally, based on existing off-the-shelves components, current day technologic developments and on-going concept demonstrations (such as the CANARY MOAO experiment) we demonstrate that the EAGLE-MOAO concept has now reached a high level of maturity compatible with an aggressive development plan for an early deployment on the telescope in its first years of activity.

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