Post-coronagraphic wave-front sensing dedicated to exoplanet detection


Sauvage Jean-Francois, Mugnier Laurent, Paul Baptiste




The final performance of current instruments dedicated to exoplanet search and imaging (such as SPHERE and EPICS) is strongly limited by uncorrected optical aberrations.

After correction of the atmospheric turbulence by an extreme AO system, the main contribution comes from the quasi-static aberrations introduced upstream of the coronagraph.

In order to measure and precompensate for these, we propose a focal-plane sensor which we call coronagraphic phase diversity (CPD). It is an adaptation of conventional phase diversity to the coronagraphic case and uses an analytical model for coronagraphic imaging.

In this communication, we validate two essential aspects of CPD:

- we validate by realistic simulations that our analytical imaging model, which assumes a perfect coronagraph, can indeed be used with real-life coronagraphs, and we assess the CPD performance;

- we perform the very first validation of CPD on experimental data obtained on an in-house AO bench.