Experimental parametric study of the self-coherent camera

TL;DR

This paper presents an experimental and numerical study of the Self-Coherent Camera (SCC), a novel instrument designed to estimate and correct wavefront aberrations in space telescopes for improved exoplanet imaging.

Contribution

It introduces the SCC with a reference hole in the Lyot stop, along with algorithms to decode fringes and estimate the electric field, demonstrating its potential for wavefront correction.

Findings

The size of the reference hole significantly affects the SCC performance.

Experimental and simulation results validate the SCC's ability to estimate the electric field.

The study provides insights into optimizing the SCC design for space-based exoplanet imaging.

Abstract

Direct imaging of exoplanets requires the detection of very faint objects orbiting close to very bright stars. In this context, the SPICES mission was proposed to the European Space Agency for planet characterization at visible wavelength. SPICES is a 1.5m space telescope which uses a coronagraph to strongly attenuate the central source. However, small optical aberrations, which appear even in space telescopes, dramatically decrease coronagraph performance. To reduce these aberrations, we want to estimate, directly on the coronagraphic image, the electric field, and, with the help of a deformable mirror, correct the wavefront upstream of the coronagraph. We propose an instrument, the Self-Coherent Camera (SCC) for this purpose. By adding a small "reference hole" into the Lyot stop, located after the coronagraph, we can produce interferences in the focal plane, using the coherence of the stellar light. We developed algorithms to decode the information contained in these Fizeau fringes and retrieve an estimation of the field in the focal plane. After briefly recalling the SCC principle, we will present the results of a study, based on both experiment and numerical simulation, analyzing the impact of the size of the reference hole.