24 September 2012 Coronagraphic phase diversity for exoplanet detection
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The final performance of current and future instruments dedicated to exoplanet detection and characterisation (such as SPHERE on the VLT, GPI on Gemini North or EPICS on E-ELT) is limited by intensity residuals in the scientific image plane, which originate in uncorrected optical aberrations. After correction of the atmospheric turbulence, the main contribution to these residuals are the quasi-static aberrations introduced upstream of the coronagraphic mask. In order to reach the final detectivity, these aberrations have to be estimated and compensated for. Some of these aberrations are not seen by the wave-front sensor of the AO loop but only by the scientific instruments. In order to measure and compensate for these aberrations, we have recently proposed a dedicated focal-plane sensor called COFFEE (for COronagraphic Focal-plane wave-Front Estimation for Exoplanet detection), based on an analytical model for coronagraphic imaging. In this communication, we first present a thorough characterisation of COFFEE’s performance, by means of numerical simulations. We additionally present an experimental validation of COFFEE for low orders aberrations using an in-house Adaptive Optics Bench and an apodized Roddier and Roddier phase mask coronagraph.
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B. Paul, B. Paul, J.-F. Sauvage, J.-F. Sauvage, L. M. Mugnier, L. M. Mugnier, M. N'Diaye, M. N'Diaye, K. Dohlen, K. Dohlen, M. Ferrari, M. Ferrari, T. Fusco, T. Fusco, } "Coronagraphic phase diversity for exoplanet detection", Proc. SPIE 8446, Ground-based and Airborne Instrumentation for Astronomy IV, 84468B (24 September 2012); doi: 10.1117/12.925382; https://doi.org/10.1117/12.925382

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