偏振光谱仪偏振探测精度分析

Polarization detection accuracy analysis of spectropolarimeter

用于野外地物偏振光谱测量的偏振光谱仪,其偏振探测精度直接影响到地物偏振光谱信息获取的准确性,进而影响到目标偏振特性的解译水平。设计了适用于光栅光谱仪的偏振测量组件,将两种型号的光栅光谱仪改装成偏振光谱仪。基于可调偏振度光源验证偏振光谱仪的偏振光谱测量精度,首先分析了偏振光谱仪的偏振敏感性,然后给出了偏振光谱仪对可调偏振度光源输出不同偏振度谱的实验测量结果。实验结果表明:在460~920 nm波长范围之间,偏振光谱仪具有一定的偏振敏感性,加装退偏器之后,偏振光谱仪对输出光的测量偏振度与可调偏振度光源输入的标准偏振度具有很好的一致性,实测值与理论值的绝对误差均在2%以内,从而验证了两种型号的偏振光谱仪偏振测量组件设计的可行性,能够满足实验测量的要求。

The accuracy of polarized detection for field-portable spectropolarimeter directly influences the precision of polarization spectrum of ground object, and thus affects the interpretation accuracy of the polarized characteristic of targets. A polarization measurement group unit was designed for grating spectrometer. Then the two kinds of grating spectrometers were transformed into spectropolarimeters. Based on variable polarization light source, the performances of the two spectropolarimeters were verified. The polarization sensitivity of the two spectropolarimeters was analyzed at first. The different degree of polarization spectra output from variable polarization light source was measured using the two spectropolarimeters. The results show that both of them have polarization sensitivity and the degree of polarization of output light measured by the two spectropolarimeters are consistent with the theoretical output of the variable polarization light source. The error between theoretical output and measured results are within 2% when the wavelength range is from 460 nm to 920 nm. It verifies that the feasibility of two spectropolarimeter polarization measurement group unit which could meet the experiment requirements.