Design and calibration of a high-sensitivity and high-accuracy polarimeter based on liquid crystal variable retarders  

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

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, Nanjing Institute of Astronomical Optics & Technology,Chinese Academy of Sciences, Nanjing 210042, China [3]Physics and Astronomy Department, California State University Northridge, 18111 Nordhoff Street, Northridge,California 91330-8268, USA [4]National Solar Observatory, Boulder, CO 80303, USA

出　　处：《Research in Astronomy and Astrophysics》2017年第1期87-96,共10页天文和天体物理学研究（英文版）

基　　金：funded by the National Natural Science Foundation of China(NSFC,Grant Nos.11661161011,11433007,11220101001,11328302,11373005 and 11303064);the Opening Project of Key Laboratory of Astronomical Optics&Technology,Nanjing Institute of Astronomical Optics&Technology,Chinese Academy of Sciences(CASKLAOT-KF201606);the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant No.XDA04075200);the special fund for astronomy of CAS(2015–2016);the special funding for Young Researcher of Nanjing Institute of Astronomical Optics&Technology;the International Partnership Program of the Chinese Academy of Sciences(Grant No.114A32KYSB20160018);the Mt.Cuba Astronomical Foundation

摘　　要：Polarimetry plays an important role in the measurement of solar magnetic fields. We devel- oped a high-sensitivity and high-accuracy polarimeter （HHP） based on nematic liquid crystal variable retarders （LCVRs）, which has a compact setup and no mechanical moving parts. The system design and calibration methods are discussed in detail. The azimuth error of the transmission axis of the polarizer as well as the fast axes of the two LCVRs and the quarter-wave plate were determined using dedicated procedures. Linearly and circularly polarized light were employed to evaluate the performance of the HHP. The experimental results indicate that a polarimetric sensitivity of better than 5.7 × 10-3 can be achieved by using a single short-exposure image, while an accuracy on the order of 10-5 can be reached by using a large number of short-exposure images. This makes the HHP a high-performance system that can be used with a ground-based solar telescope for high-precision solar magnetic field investigations.Polarimetry plays an important role in the measurement of solar magnetic fields. We devel- oped a high-sensitivity and high-accuracy polarimeter （HHP） based on nematic liquid crystal variable retarders （LCVRs）, which has a compact setup and no mechanical moving parts. The system design and calibration methods are discussed in detail. The azimuth error of the transmission axis of the polarizer as well as the fast axes of the two LCVRs and the quarter-wave plate were determined using dedicated procedures. Linearly and circularly polarized light were employed to evaluate the performance of the HHP. The experimental results indicate that a polarimetric sensitivity of better than 5.7 × 10-3 can be achieved by using a single short-exposure image, while an accuracy on the order of 10-5 can be reached by using a large number of short-exposure images. This makes the HHP a high-performance system that can be used with a ground-based solar telescope for high-precision solar magnetic field investigations.

关 键 词：instrumentation polarimeters - methods laboratory - Sun magnetic fields - tech-niques polarimetric 

分 类 号：P111.41[天文地球—天文学]