AI 中文总结
研究基于MagAO-X升级后的高对比度偏振差分成像功能，表征其偏振响应并部署DQWP补偿器，提升偏振效率、降低仪器偏振，最终实现对HR 4796碎屑盘的近内工作角观测，为未来超大型望远镜偏振计应用奠定基础。
AI 中文摘要
MagAO-X是安装在6.5米麦哲伦克莱望远镜上的可见光极端自适应光学仪器，最近已升级，可在r'、i'和z'滤光片下实现高对比度偏振差分成像（PDI）。偏振测量是一种强大的技术，可用于抑制非偏振恒星光并分离星际尘埃散射的微弱偏振信号，但它需要精确校准望远镜和仪器光学元件引入的仪器偏振效应。我们概述了MagAO-X偏振计，并使用专门构建的偏振发生器（可注入已知偏振态的光）表征其偏振响应。根据这些测量结果，我们拟合了该仪器的穆勒矩阵模型，并量化了其偏振效率和仪器偏振随k镜图像旋转器角度及观测滤光片的变化。初始表征揭示了由图像旋转器驱动的显著动态低效率，这促使我们部署了双旋转四分之一波片（DQWP）补偿器，该补偿器可动态调整输入偏振至仪器的本征偏振。DQWP安装后，我们测量到所有滤光片的偏振效率平均提升了17.5%（至87.4%），仪器偏振降低了5.4%（至8.3%）。最后，我们通过对HR 4796周围碎屑盘进行i'成像，展示了该偏振计的在轨性能，获得了该碎屑盘明亮前向散射侧的近内工作角视图之一。这些结果为未来超大型望远镜（如GMT和ELT）上的偏振计应用铺平了道路。
英文摘要
MagAO-X is a visible-light extreme adaptive optics instrument on the 6.5 meter Magellan Clay Telescope, recently upgraded to enable high-contrast polarimetric differential imaging (PDI) in r', i', and z' filters. Polarimetry is a powerful technique for suppressing unpolarized starlight and isolating the faint, polarized signal scattered by circumstellar dust, but it demands precise calibration of instrumental polarization effects introduced by the telescope and instrument optics. We present an overview of the MagAO-X polarimeter and characterize its polarimetric response using a purpose-built polarization generator that injects light of a known polarization state. From these measurements, we fit a Mueller-matrix model of the instrument and quantify its polarimetric efficiency and instrumental polarization as a function of the k-mirror image rotator angle and observing filter. The initial characterization revealed significant, dynamic inefficiencies driven by the image rotator, motivating the deployment of a dual rotating quarter-wave plate (DQWP) compensator that dynamically reorients the input polarization to the instrument's eigenpolarization. Following installation of the DQWP, we measured an average increase in polarimetric efficiency of +17.5% (to 87.4%) and a reduction in instrumental polarization of -5.4% (to 8.3%) across all filters. Finally, we demonstrate the on-sky performance of the polarimeter with i' imaging of the debris disk around HR 4796, producing one of the closest inner-working-angle views of the bright, forward-scattering side of the disk. These results help pave the way for polarimeters on future extremely large telescopes such as GMT and ELT.
Comments20 pages, 11 figures, proceeding of SPIE Astronomical Telescopes + Instrumentation 2026 (Paper No. 14149-212)
