A high-contrast imaging coronagraph for segmented-mirror large aperture telescopes using a spatial light modulator

The primary mirrors of current and future large telescopes always employ a segmented mirror configuration. The small but non-negligible gaps between neighboring segments cause additional diffraction, which restricts the performance of high-contrast coronagraph. To solve this problem, we propose a coronagraph system based on a single liquid crystal spatial light modulator (SLM). This spatial light modulator is used for amplitude apodization, and its feasibility and potential performance are demonstrated using a laboratory setup using the stochastic parallel gradient descent (SPGD) algorithm to control the spatial light modulator, which is based on point spread function (PSF) sensing and evaluation and optimized for maximum contrast in the discovery working area as a merit function. The system delivers a contrast in the order of 10⁻⁶, and shows excellent potential to be used in current and future large aperture telescopes, both on the ground and in space.