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25 October 2004 High-contrast imaging with ELTs: effects of cophasing and AO residual errors on the PSF contrast
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Direct detection and characterization of terrestrial extrasolar planets are now a high-priority scientific program where new major results from extremely large telescopes (ELTs) are expected. This application is also the most demanding for the adaptive optics (AO) and the mirror segment cophasing. To optimize the fundamental performances of an ELT in high-contrast imaging, we compare the effects of segment cophasing errors with the effects of each AO residual phase errors (wavefront sensor noise, fitting, aliasing, servo-lag) on the long-exposure point-spread function halo. We emphasize that an adaptive correction of the differential segment piston at a nanometric level is needed to keep the contrast gain provided by a high-order AO. We show the potential advantages of an adaptive primary mirror for this purpose. Lastly, we present the planet detection performances in the photon-noise-limited case for different telescopes, AO parameters, and observational conditions (star magnitudes and sites).
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Olivier Lardiere, Marcel Carbillet, Armando Riccardi, and Piero Salinari "High-contrast imaging with ELTs: effects of cophasing and AO residual errors on the PSF contrast", Proc. SPIE 5490, Advancements in Adaptive Optics, (25 October 2004);

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