A high-contrast imaging polarimeter with a stepped-transmission filter based coronagraph  

作　　者：Cheng-Chao Liu De-Qing Ren Yong-Tian Zhu Jiang-Pei Dou Jing Guo 

机构地区：[1]National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology,Chinese Academy of Sciences,Nanjing 210042,China [2]Key Laboratory of Astronomical Optics&Technology,National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology,Chinese Academy of Sciences,Nanjing 210042,China [3]Physics&Astronomy Department California State University Norihridge,18111 Nordhoff Street,Northridge,California 91330-8268,USA [4]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Research in Astronomy and Astrophysics》2016年第5期25-30,共6页天文和天体物理学研究（英文版）

基　　金：supported by the NSFC(Grant Nos.11220101001,11433007,11328302,11373005 and 11303064);the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant Nos.XDA04070600 and XDA04075200);the special funding for Young Researchers of Nanjing Institute of Astronomical Optics&Technology;the special fund for astronomy(Grant No.KT2013-022)of CAS.;carried out at California State University Northridge,with support from the Mt.Cuba Astronomical Foundation

摘　　要：The light reflected from planets is polarized mainly due to Rayleigh scattering, but starlight is normally unpolarized. Thus it provides an approach to enhance the imaging contrast by inducing the imaging polarimetry technique. In this paper, we propose a high-contrast imaging polarimeter that is op- timized for the direct imaging of exoplanets, combined with our recently developed stepped-transmission filter based coronagraph. Here we present the design and calibration method of the polarimetry system and the associated test of its high-contrast performance. In this polarimetry system, two liquid crystal variable retarders （LCVRs） act as a polarization modulator, which can extract the polarized signal. We show that our polarimeter can achieve a measurement accuracy of about 0.2% at a visible wavelength （632.8 nm） with linearly polarized light. Finally, the whole system demonstrates that a contrast of 10 9 at 5A/D is achievable, which can be used for direct imaging of Jupiter-like planets with a space telescope.The light reflected from planets is polarized mainly due to Rayleigh scattering, but starlight is normally unpolarized. Thus it provides an approach to enhance the imaging contrast by inducing the imaging polarimetry technique. In this paper, we propose a high-contrast imaging polarimeter that is op- timized for the direct imaging of exoplanets, combined with our recently developed stepped-transmission filter based coronagraph. Here we present the design and calibration method of the polarimetry system and the associated test of its high-contrast performance. In this polarimetry system, two liquid crystal variable retarders （LCVRs） act as a polarization modulator, which can extract the polarized signal. We show that our polarimeter can achieve a measurement accuracy of about 0.2% at a visible wavelength （632.8 nm） with linearly polarized light. Finally, the whole system demonstrates that a contrast of 10 9 at 5A/D is achievable, which can be used for direct imaging of Jupiter-like planets with a space telescope.

关 键 词：instrumentation： polarimeter coronagraph-- techniques： polarimetric -- methods： laboratory 

分 类 号：P111.41[天文地球—天文学]