Mach-Zehnder Wavefront sensing in the context of Extreme Adaptive Optics on Extremely large telescopes
M. Langlois, M. Tallon, E. Thiébaut
CENTRE DE RECHERCHE ASTROPHYSIQUE DE LYON
We present results on the use of the Mach-Zehnder wavefront sensor in the context of Extreme Adaptive Optics (EXAO) on ELTs. Thanks to a very good sensitivity at high spatial frequencies, such wavefront sensor favors a clean correction of the starlight halo at small angular separations where the most demanding contrast is required, but its use is hampered by its non-linear response. It has already been studied in the context of 8m-class telescope (Langlois 2001) and shows very low noise propagation. In this paper we concentrate on the development of analytical and numerical modeling of the Mach-Zehnder in the ELTs context. This work is preparatory to the development of new methods for fast reconstruction with this type of wavefront sensor based on the sparseness advantage and Fractal Iterative method (Béchet, 2006) and the study of the inverse approach to unable very large dynamic wavefront measurement.