星载多角度偏振成像仪偏振辐射测量的理论误差分析

The Polarized Radiometric Theoretical Error of Spaceborne Directional Polarimetric Camera

星载多角度偏振成像仪可以获取目标的多角度偏振辐射信息,探测精度是重要的技术指标。为研究仪器的测量精度及相关的误差因素,以Stokes-Mueller为数学描述方法,分析仪器的原理和光路结构特点,从理论上推导了仪器的偏振辐射测量模型,并通过实验初步验证了镜头Mueller模型的正确性。在考虑目标光各种偏振态的情况下,分析了非理想光学器件重要参数对目标光偏振度测量结果的影响,得到了偏振度测量误差与通道相对透射率、空间高频相对透射率/响应率、线偏振片振透轴方位角、镜头线性双向衰减这四种参数偏差之间的关系。按照仪器探测精度要求,结合各参数偏差对应误差最敏感的目标光偏振态,从理论上提出了各重要参数的误差容限。该研究为整个仪器的研制、定标及后期数据处理提供了理论依据。

The measurement accuracy is an important technical index of the Spaceborne Directional Polarimetric Camera which achieves multiangle polarimetric information in target detection.In order to research the elements affecting the measurement accuracy of the instrument,the polarized radiometric theoretical model of every single pixel of the instrument which contains parameters representing physical concept clearly is established in steps by using mathematical description called Stokes-Muller and analyzing characteristics of the instrumental optical structure.The theoretical measurement errors of Degree of Linear Polarization on a single pixel,introduced by some important parameter deviations of all the components in the instrument,is calculated and analyzed.The results shows that there might exsit proportional relationship between the theoretical measurement errors of Degree of Linear Polarization and the deviation of the relative transmission of the channels,the deviation of the high frequency part of the spatial variation of the transmission mainly due to the inter-pixel sensitivity variation,the deviation of the orientation of the polarizer,the deviation of the polarization rate of the optics.When the deviations of the parameters exist,the theoretical measurement errors of Degree of Linear Polarization affected by the different kinds of incident light are acquired.According to the measurement accuracy of the instrument,the tolerances of the parameters are proposed for the most sensitive kinds of incident lights by the way of equal distribution of the errors.The study provides a theoretical basis and practical guidance for the development,calibration and data post-processing of the Directional Polarimetric Camera.