Reconstruction Strategies for GeMS

Gemini Observatory, c/o AURA, Casilla 603 La Serena, Chile

^a e-mail: bneichel@gemini.edu

Abstract

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 relative to the LGS high-order path. We compare the performance obtained by a Least-Square Estimator (LSE) and a Minimum Mean Square Error (MMSE) reconstructor. The MMSE reconstructor is found to improve the performance compared to the classical LSE, particularly when the system is affected by noise. We show the results obtained by realistic simulations as well as the first results obtained in laboratory on CANOPUS, the GeMS AO bench.