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Tomographic reconstruction strategies for Gemini’s MCAO system.

Abstract 128

Submitted by Benoit NEICHEL


B. Neichel (1), F. Rigaut (1), D. Gratadour (2), A. Garcia (1)


(1) Gemini Observatory ; (2) Observatoire de Paris - LESIA


The Gemini Multi-Conjugate Adaptive Optics System (GEMS) is a facility instrument for the Gemini-South telescope that can provide near-uniform atmospheric compensation over a 1 arc minute square field of view. To provide diffraction-limited image quality at near IR wavelengths across an extended field-of-view, the system includes 5 laser guide stars, 3 natural guide stars and 3 deformable mirrors optically conjugated at 0, 4.5 and 9km. By many ways, GEMS represents a unique system to prepare and understand any future wide field AO systems planned for the ELTs. In this paper, we present the different strategies developed for the phase volume estimation and correction. We investigate the performance achieved by a least square reconstructor, a more sophisticated reconstruction upon virtual deformable mirrors, and a minimum variance approach. We show the results obtained by realistic simulations as well as the first results obtained in laboratory on CANOPUS, the GEMS AO bench.