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An adaptive optics (AO) system based on stochastic parallel gradient descent(SPGD) algorithm is proposed to reduce the speckle noises in the optical systemof stellar coronagraph in order to further improve the contrast. The principleof SPGD algorithm is described briefly and a metric suitable for point sourceimaging optimization is given. The feasibility and good performance of SPGDalgorithm is demonstrated by experimental system featured with a 140-actuatorsdeformable mirror (DM) and a Hartmann- Shark wavefront sensor. Then the SPGDbased AO is applied to a liquid crystal array (LCA) based coronagraph. The LCAcan modulate the incoming light to generate a pupil apodization mask in anypattern. A circular stepped pattern is used in our preliminary experiment andthe image contrast shows improvement from 10^-3 to 10^-4.5 at angular distanceof 2{\lambda}/D after corrected by SPGD based AO.

Stochastic parallel gradient descent based adaptive optics used for high contrast imaging coronagraph