title: Improving the performance of a pyramid wavefront sensor with modal sensitivity compensation.
abstract: We describe a solution to increase the performance of a pyramid wavefront sensor (P-WFS) under bad seeing conditions. We show that most of the issues involve a reduced sensitivity that depends on the magnitude of the high frequency atmospheric distortions. We demonstrate in end-to-end closed loop adaptive optics simulations that with a modal sensitivity compensation method a high-order system with a nonmodulated P-WFS is robust in conditions with the Fried parameter r 0 at 0.5 microm in the range of 0.05-0.10 m. We also show that the method makes it possible to use a modal predictive control system to reach a total performance improvement of 0.06-0.45 in Strehl ratio at 1.6 microm. Especially at r 0=0.05 m the gain is dramatic.
authors.affiliation: European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching b. München, Germany. vkorkiak@eso.org
authors.forename: Visa
authors.initials: V
authors.lastname: Korkiakoski
authors.forename: Christophe
authors.initials: C
authors.lastname: Vérinaud
authors.forename: Miska
authors.initials: M
authors.lastname: Le Louarn