A High-Efficiency and High-Accuracy Polarimeter for Solar Magnetic Field Measurements
A High-Efficiency and High-Accuracy Polarimeter for Solar Magnetic Field Measurements
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DOI：
10.1007/s11207-020-01676-2
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发表时间：
2020-08
期刊：
影响因子：
2.8
通讯作者：
D. Ren;Zijian Han;Jing Guo
中科院分区：
文献类型：
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作者：
D. Ren;Zijian Han;Jing Guo
太阳活动受磁场支配。如今，偏振仪是测量太阳磁场的必备工具，太阳磁场通常很微弱，与-数量级的偏振相对应。因此，高效率、高精度的极化测量对于研究微弱磁场是至关重要的。本文提出了一种基于向列型液晶可变延迟器(LCVR)和Wollaston棱镜(WP)的高效率、高精度的偏振测量仪。它使用专用的斯托克斯调制策略来实现高效率。研制了用于测量旋光仪响应矩阵的定标单元(CU)，提供了高精度的定标以校正可能的系统误差。与其他传统的旋光仪相比，我们的旋光仪的调制方式是灵活的。除了能够同时测量所有三个斯托克斯偏振分量(、、或)外，它还可以单独测量其中的一个或两个偏振分量，具有很高的偏振效率。我们为我们的旋光仪开发了专门的对准和校准技术，并实现了高测量精度。在我们的实验室实验测试中，我们基于两幅图像的偏振测量提供了一个数量级的总体测量精度，与我们以前使用传统的四像偏振调制的偏振测量仪相比，大约提高了10倍。这项工作为未来太阳天气观测的高效率、高精度的偏振测量提供了新的选择。
Solar activity is dominated by the magnetic field. Nowadays, a polarimeter is a mandatory tool to measure solar magnetic fields, which are generally faint and correspond to a polarization of an order of–. As such, polarization measurements of high efficiency with a high accuracy are crucial to investigate faint magnetic fields. Here we propose a high-efficiency and high-accuracy polarimeter, which is based on a pair of nematic liquid crystal variable retarders (LCVRs) and a Wollaston prism (WP). It uses a dedicated Stokes modulation strategy to achieve high efficiency. A calibration unit (CU) is developed to measure the polarimeter response matrix, which provides a high-precision calibration to correct possible systematic errors. Compared with other traditional polarimeters, the modulation scheme of our polarimeter is flexible. In addition to be able to measure all the three Stokes polarization components (,, or) simultaneously, it can also measure one or two of these polarization components alone, with high polarization efficiency. Dedicated alignment and calibration techniques optimized for our polarimeter are developed and high measurement accuracy is achieved. In our laboratory experimental test, our two-image based polarization measurement delivers an overall measurement accuracy of the order of, which is about 10 times better, compared with our previous polarimeters that use the traditional four-image polarization modulation. This work provides a new option for high-efficiency and high-accuracy polarization measurement for future solar synoptic observations.