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Proceedings Paper

A coronagraph based on two spatial light modulators for active amplitude apodizing and phase corrections
Author(s): Jiangpei Dou; Deqing Ren; Xi Zhang; Yongtian Zhu; Gang Zhao; Zhen Wu; Rui Chen; Chengchao Liu; Feng Yang; Chao Yang
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Paper Abstract

Almost all high-contrast imaging coronagraphs proposed until now are based on passive coronagraph optical components. Recently, Ren and Zhu proposed for the first time a coronagraph that integrates a liquid crystal array (LCA) for the active pupil apodizing and a deformable mirror (DM) for the phase corrections. Here, for demonstration purpose, we present the initial test result of a coronagraphic system that is based on two liquid crystal spatial light modulators (SLM). In the system, one SLM is served as active pupil apodizing and amplitude correction to suppress the diffraction light; another SLM is used to correct the speckle noise that is caused by the wave-front distortions. In this way, both amplitude and phase error can be actively and efficiently compensated. In the test, we use the stochastic parallel gradient descent (SPGD) algorithm to control two SLMs, which is based on the point spread function (PSF) sensing and evaluation and optimized for a maximum contrast in the discovery area. Finally, it has demonstrated a contrast of 10-6 at an inner working angular distance of ~6.2 λ/D, which is a promising technique to be used for the direct imaging of young exoplanets on ground-based telescopes.

Paper Details

Date Published: 6 August 2014
PDF: 11 pages
Proc. SPIE 9147, Ground-based and Airborne Instrumentation for Astronomy V, 91478O (6 August 2014); doi: 10.1117/12.2055327
Show Author Affiliations
Jiangpei Dou, Nanjing Institute of Astronomical Optics and Technology (China)
Deqing Ren, Nanjing Institute of Astronomical Optics and Technology (China)
California State Univ., Northridge (United States)
Xi Zhang, Nanjing Institute of Astronomical Optics and Technology (China)
Yongtian Zhu, Nanjing Institute of Astronomical Optics and Technology (China)
Gang Zhao, Nanjing Institute of Astronomical Optics and Technology (China)
Zhen Wu, Nanjing Institute of Astronomical Optics and Technology (China)
Rui Chen, Nanjing Institute of Astronomical Optics and Technology (China)
Chengchao Liu, Nanjing Institute of Astronomical Optics and Technology (China)
Univ. of Chinese Academy of Sciences (China)
Feng Yang, Nanjing Institute of Astronomical Optics and Technology (China)
Univ. of Chinese Academy of Sciences (China)
Chao Yang, Nanjing Institute of Astronomical Optics and Technology (China)
Univ. of Chinese Academy of Sciences (China)


Published in SPIE Proceedings Vol. 9147:
Ground-based and Airborne Instrumentation for Astronomy V
Suzanne K. Ramsay; Ian S. McLean; Hideki Takami, Editor(s)

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