Laboratory results for speckle suppression with a self-coherent camera.
Pierre Baudoz(1), Marion Mas(1), Raphael Galicher(2), Gerard Rousset(1)
1 :LESIA, Observatoire de Paris-Meudon, France 2: Herzberg institute of astrophysics , Victoria, Canada
Direct imaging is a powerful tool for exoplanet atmosphere characterization. High performance of these techniques requires extreme wavefront correction for ground-based instruments as well as space projects. Wavefront sensors are usually physically separated from the common optics by a beam splitter in classical AO system. This separation introduces differential aberrations that are not measured by the wavefront sensor, which limits the performance of a planet finder instrument. We propose to use a Self-Coherent Camera (SCC) to directly measure the differential aberrations in the final coronagraphic science focal plane. The SCC is based on the principle of light coherence and allows us to estimate the wavefront errors upstream the coronagraph by spatially encoding the speckles with fringes in the final image. After recalling the SCC principle, we will present laboratory results on speckle suppression and compare it with expected performances from numerical simulations. We will also show the solution we developed to measure and correct the tip-tilt errors directly from the coronagraphic image.