The segmented pupil experiment for exoplanet detection. 4. A versatile image-based wavefront sensor for active optics

Abstract

SPEED – the segmented pupil experiment for exoplanet detection – currently in final integration phase, is designed to test strategies and technologies for high-contrast instrumentation with segmented telescopes by offering an ideal cocoon to progress in these domains with complex telescope apertures. SPEED combines precision segment phasing architectures, optimised small inner-working angle (IWA) coronagraphy, and wavefront shaping to create a small IWA and small field of view (FoV) dark hole in the science detector. Over the years SPEED has made significant hardware and software progress to start the exploitation of the bench. We have completed several key hardware including the common-path wavefront sensor for cophasing optics based on the self-coherent camera (SCC) concept. In this paper, we report on the wavefront sensing strategy designed for SPEED, from the adaptation of the SCC concept to cophasing optics towards an alternative implementation of the conventional SCC, called the fast-modulated SCC, for both wavefront control and shaping applications. We present a progress overview on this wavefront sensor for (i) cophasing control and monitoring from the scientific image, as well as (ii) its interest for the wavefront shaping unit of the bench.