旋光退偏器用于星载光栅成像光谱仪分析

对紫外-可见光谱区星载光栅光谱仪的响应偏振敏感性的问题,采用加入退偏器的方法来消除仪器的偏振响应,保证成像光谱仪测量结果的准确性.退偏器根据大气偏振的特点采用简单双光楔结构旋光退偏器,给出了其退偏度理论表达式,计算分析了系统的线性偏振敏感度.采用矩阵计算法推导分析了退偏器的偏振像差矩阵和光学传递矩阵,重点分析了退偏器引入的双像对成像光谱仪像质的影响.分析结果表明,加入退偏器后,仪器偏振响应敏感度小于1%,系统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.

Analysis of Rotation Depolarizer for the Space-borne Grating Imaging Spectrometer

In the ultraviolet and visible part of the spectrum,measurements of space-borne grating spectrometers are in general sensitive to the state of polarization of the observed light.One method to overcome polarization bias to measure the intensity accurately in imaging spectrometers is the insertion of a depolarizer.The double plate rotation depolarizer with simple structure was chosen according to the atmospheric polarization characteristics.The theoretical expression of depolarization and its effect on system linear polarization sensitivity(LPS)were described.The polarization aberration matrix(PAM)and optical transfer matrix(OTM)of the depolarizer were computed using matrix calculus.The image degradation(especially the image doubling)induced by the depolarizer using optical transfer matrix was analyzed for the depolarizer design.The results showed that it satisfied the design requirements of the spectrometer,the linear polarization sensitivity within the specification of 1% and the decrease in MTF due to the depolarizer less than 1.5%.