标题： SCExAO-CHARIS光谱偏振模式仪器偏振效应的校准 显示英文标题

标题： Calibration of the instrumental polarization effects of SCExAO-CHARIS' spectropolarimetric mode

摘要： SCExAO在 Subaru 望远镜上是一个可见光和近红外高对比度成像仪器，使用极端自适应光学和日冕观测法。 该仪器将近红外光（JHK）引导至积分场光谱仪CHARIS。 最近，在CHARIS的光路中增加了一个沃拉斯顿棱镜，使CHARIS获得了独特的光谱偏振能力，这是高对比度成像仪器中独一无二的。 我们提出一个详细的穆勒矩阵模型，描述了整个光学路径，包括望远镜和仪器的仪器偏振效应。 CHARIS的22个波长区间提供了独特的机会来详细研究仪器偏振效应的波长依赖性。 通过内部光源的测量，我们发现图像旋转变换器（K镜）产生了强烈的波长依赖性串扰，在最坏的情况下将约95%的入射线性偏振转换为无法测量的圆偏振光。 理论计算表明，望远镜的仪器偏振效应随着波长在大约0.5%到0.7%之间变化，并且其角度正好等于望远镜的高度角。 我们计划通过观测偏振标准星更准确地确定望远镜的仪器偏振，并拟合更全面的物理模型以匹配所有实验数据。 此外，我们计划将完整的穆勒矩阵模型集成到现有的CHARIS后处理管道中，目标是在线性偏振的程度上实现小于0.1%的偏振精度。 我们的CHARIS光谱偏振模式校准将使我们能够进行独特的定量偏振研究，涉及环绕恒星盘以及行星和褐矮星伴星。 显示英文摘要

摘要： SCExAO at the Subaru telescope is a visible and near-infrared high-contrast imaging instrument employing extreme adaptive optics and coronagraphy. The instrument feeds the near-infrared light (JHK) to the integral field spectrograph CHARIS. Recently, a Wollaston prism was added to CHARIS' optical path, giving CHARIS a spectropolarimetric capability that is unique among high-contrast imaging instruments. We present a detailed Mueller matrix model describing the instrumental polarization effects of the complete optical path, thus the telescope and instrument. The 22 wavelength bins of CHARIS provide a unique opportunity to investigate in detail the wavelength dependence of the instrumental polarization effects. From measurements with the internal light source, we find that the image derotator (K-mirror) produces strong wavelength-dependent crosstalk, in the worst case converting ~95% of the incident linear polarization to circularly polarized light that cannot be measured. Theoretical calculations show that the magnitude of the instrumental polarization of the telescope varies with wavelength between approximately 0.5% and 0.7%, and that its angle is exactly equal to the altitude angle of the telescope. We plan to more accurately determine the instrumental polarization of the telescope with observations of a polarization standard star, and fit more comprehensive physical models to all experimental data. In addition, we plan to integrate the complete Mueller matrix model into the existing CHARIS post-processing pipeline, with the aim to achieve a polarimetric accuracy of <0.1% in the degree of linear polarization. Our calibrations of CHARIS' spectropolarimetric mode will enable unique quantitative polarimetric studies of circumstellar disks and planetary and brown dwarf companions.