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

作　　者：Bing Dong De-Qing Ren Xi Zhang 

机构地区：[1]Physics ＆ Astronomy Department, California State University Northridge, CA, 91330-8268, USA [2]National Astronomical Observatories/Nanjing Institute of Astronomical Optics ＆ Technology, Chinese Academy of Sciences, Nanjing, 210042, China

出　　处：《Research in Astronomy and Astrophysics》2011年第8期997-1002,共6页天文和天体物理学研究（英文版）

基　　金：Supported by the National Natural Science Foundation of China(Grant Nos. 10873024 and 11003031);supported by the National Science Foundation under Grant ATM-0841440

摘　　要：An adaptive optics （AO） system based on a stochastic parallel gradient descent （SPGD） algorithm is proposed to reduce the speckle noises in the optical system of a stellar coronagraph in order to further improve the contrast. The principle of the SPGD algorithm is described briefly and a metric suitable for point source imaging optimization is given. The feasibility and good performance of the SPGD algorithm is demonstrated by an experimental system featured with a 140-actuator deformable mirror and a Hartrnann-Shark wavefront sensor. Then the SPGD based AO is applied to a liquid crystal array （LCA） based coronagraph to improve the contrast. The LCA can modulate the incoming light to generate a pupil apodization mask of any pattern. A circular stepped pattern is used in our preliminary experiment and the image contrast shows improvement from 10^-3 to 10^-4.5 at an angular distance of 2A/D after being corrected by SPGD based AO.An adaptive optics （AO） system based on a stochastic parallel gradient descent （SPGD） algorithm is proposed to reduce the speckle noises in the optical system of a stellar coronagraph in order to further improve the contrast. The principle of the SPGD algorithm is described briefly and a metric suitable for point source imaging optimization is given. The feasibility and good performance of the SPGD algorithm is demonstrated by an experimental system featured with a 140-actuator deformable mirror and a Hartrnann-Shark wavefront sensor. Then the SPGD based AO is applied to a liquid crystal array （LCA） based coronagraph to improve the contrast. The LCA can modulate the incoming light to generate a pupil apodization mask of any pattern. A circular stepped pattern is used in our preliminary experiment and the image contrast shows improvement from 10^-3 to 10^-4.5 at an angular distance of 2A/D after being corrected by SPGD based AO.

关 键 词：instrumentation： adaptive optics -- methods： laboratory -- techniques： image processing CORONAGRAPH 

分 类 号：TP183[自动化与计算机技术—控制理论与控制工程] O439[自动化与计算机技术—控制科学与工程]