Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Opt Lett. 2013 May 15;38(10):1657-9. doi: 10.1364/OL.38.001657.
Channeled spectropolarimeters measure the polarization state of light as a function of wavelength. Typically, a channeled spectropolarimeter uses high-order retarders made of uniaxial crystal to amplitude modulate the measured spectrum with the Stokes polarization information. A primary limitation of these instruments is the thermal variability of the retarders, which necessitates frequent system recalibration. Past work has addressed this issue by implementing an athermalized retarder produced from two uniaxial crystals. However, reducing the complexity of an athermalized retarder is advantageous for minimizing size and weight requirements. In this Letter, a technique for producing a thermally stable channeled spectropolarimeter using biaxial retarders is presented. This technique preserves a constant phase over an appreciable temperature range. Proof-of-concept results from a KTP-based athermal partial channeled spectropolarimeter are presented from 500 to 750 nm for temperature changes up to 26°C. Spectropolarimetric reconstructions produced from this system vary by <=2.6% RMS when the retarder experiences a 13°C increase in temperature above 21°C ambient, <=5.2% for a 20°C increase, and <=6.7% for a 26°C increase.
通道光谱偏振仪测量光的偏振状态作为波长的函数。通常，通道光谱偏振仪使用由单轴晶体制成的高阶延迟器，用斯托克斯偏振信息对测量光谱进行幅度调制。这些仪器的一个主要限制是延迟器的热变性，这需要频繁的系统重新校准。过去的工作通过实现由两个单轴晶体制成的热补偿延迟器来解决这个问题。然而，减少热补偿延迟器的复杂性有利于最小化尺寸和重量要求。在这篇文章中，提出了一种使用双轴延迟器制作热稳定的通道光谱偏振仪的技术。这种技术在相当大的温度范围内保持恒定的相位。从 500 到 750nm 提出了基于 KTP 的热部分通道光谱偏振仪的原理验证结果，温度变化高达 26°C。当延迟器在 21°C 环境温度以上升高 13°C 时，该系统产生的光谱偏振重建变化 <=2.6% RMS，当延迟器在 20°C 升高 20°C 时，变化 <=5.2%，在 26°C 升高 26°C 时，变化 <=6.7%。
