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Experimental results of tomographic reconstruction on ONERA laboratory MCAO bench

Abstract 182

Submitted by Anne COSTILLE


A. Costille (1), C. Petit (1), J.-M. Conan (1), T. Fusco (1), C. Kulcsar (2), H.-F. Raynaud (2)


(1) ONERA - DOTA - Unité HRA ; (2) L2TI - Université Paris 13.


Classic Adaptive Optics (AO) is now a proven technique to correct turbulence for earth based astronomical telescopes. But the corrected Field of View (FoV)is however limited by the anisoplanatism effect. Many concepts of wide field AO systems are now under study, especially for ELT’s instruments. These systems allow a tomographic reconstruction of the turbulent volume thanks to the use of several WaveFront Sensor (WFS). They can provide a correction in a specific direction (Laser Tomography AO system) with one Deformable Mirror (DM) or in a wide FoV (Multi Conjugate AO system) with several DMs conjugated to different altitude. The performance optimization of such complex systems raises inevitably new questions in terms of calibration and control. We present our current developments on performance optimization of wide field AO system. We show that performance can be significantly improved with tomographic control based on Linear Quadratic Gaussian control, compared to more standard methods. The associated calibration and system modeling strategy is described. We especially study the calibration of the WFS references in a multi guide stars configuration. This issue is related to distorsion effects and astrometric precision. An experimental demonstration of these studies is presented on Homer. Homer is the recent bench developed at ONERA devoted to MCAO and wide field AO laboratory research. This bench implements two deformable mirrors and a wide field Shack-Hartmann WFS.

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