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Sensing Quasi-Static Aberrations of Adaptive Optics Systems On Line with Long-Exposure Phase Diversity

Abstract 150

Submitted by Laurent MUGNIER


L. M. Mugnier(1), J.-F. Sauvage(1), T. Fusco(1), S. Dandy(1), A. Cornia(2)


(1) ONERA; (2)ONERA/DOTA and Obs. Paris / LESIA


We propose and validate by simulations an extension of the phase diversity technique that uses long exposure adaptive optics corrected images for sensing quasi-static aberrations during the scientific observation, in particular for high-contrast imaging. The principle of the method is that, for a sufficiently long exposure time, the residual turbulence is averaged into a convolutive component of the image and that phase diversity estimates the sole static aberrations of interest.

The advantages of such a procedure, compared to the processing of short- exposure image pairs, are that the separation between static aberrations and turbulence-induced ones is performed by the long-exposure itself and not numerically, that only one image pair must be processed, that the estimation benefits from the high SNR of long-exposure images, and that only the static aberrations of interest are to be estimated. Long-exposure phase diversity can also be used as a phasing sensor for a segmented aperture telescope. Thus, it may be particularly useful for future planet finder projects such as EPICS on the European ELT.

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