星载光栅成像光谱仪的退偏器设计与分析

星载光栅成像光谱仪中的光栅通常有着强烈的偏振响应,为保证成像光谱仪测量结果的准确性,加入退偏器是消除光学系统的偏振响应的一种常用方法.对水平-垂直(H-V)型石英退偏器的退偏原理进行了理论分析,根据成像光谱仪的偏振响应特点,采用一片H-V型石英退偏器即可实现光谱仪的退偏要求.重点分析了退偏器引入的双像对成像光谱仪像质的影响,分析的结果表明,加入退偏器后,仪器偏振响应敏感度小于1%,MTF下降小于1.5%,像质满足使用要求,完全可应用于星载光栅成像光谱仪.

Design and analysis of a depolarizer for the space-borne grating imaging spectrometer

The main portion of the space-borne grating imaging spectrometer-grating has intense polarization response. The objective of spectrometer is to measure the intensity accurately without bias as to the incident polarization state. One common method to overcome polarization bias in optical systems is the insertion of a depolarizer. The theory of horizontal-vertical (H-V) quartz depolarizer operation is described. A single H-V depolarizer was met the spectrometer polarization requirement according to its polarization character. Both the degree of depolarization and image degradation (especially the image doubling) were analyzed for the depolarizer design. The analysis results show that it satisfies the design requirements of the spectrometer, the polarization sensitivity is within the specification of 1% and the decrease in MTF due to the depolarizer is less than 1.5%.