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星载多角度偏振成像仪自身的光学系统有一定的偏振效应,会影响非偏通道的辐射测量精度.斜入射到光学元件上的光透射率是偏振敏感的,导致了光学系统的线偏振效应.为精确反演解析出观测目标光的辐射强度,需对成型仪器本身的偏振效应进行准确的测量、定标、校正.通过分析仪器原理和光路结构,详细推导出仪器非偏通道含线偏振效应的辐射测量模型,并根据实际镜头特点合理简化了模型.提出了基于不同偏振角的完全线偏光在仪器全视场内稀疏入射并最小二乘拟合响应值的方法,对非偏通道全视场线偏振效应进行测量和定标,同时对此方法的定标过程进行了仿真.另外,分析了仪器主要物理参数有偏差时对不同偏振态入射光的反演误差,如仪器单像元方位角、显式起偏效应、低频透过率.对仪器开展了实验室定标实验,得到了仪器主要物理参数范围及其拟合偏差量,进一步算出显式起偏效应参数偏差引起的辐射定标强度相对误差最大为0.4%,满足仪器辐射精度5%的要求并留足余量.该研究为仪器非偏通道全视场的高精度辐射测量、定标及后期数据处理提供了理论依据及实验指导.
The optical system of a spaceborne multi-angle polarimeter itself has a polarization effect that affects the radiometric accuracy of non-deflected channels. The transmission of light obliquely onto an optical element is polarization-sensitive and results in a linear polarization effect of the optical system In order to accurately derive the radiation intensity of the observation target light, the polarization effect of the molding instrument itself needs to be accurately measured, calibrated and calibrated.According to the principle of the instrument and the optical path structure, the nonlinear polarization Effect of the radiation measurement model, and based on the actual lens characteristics of a reasonable simplification of the model.Furthermore, a method based on sparse incidence and least-squares fitting response of full linearly polarized light in the whole field of the instrument based on different polarization angles is proposed, The linear polarization effect of the field of view is measured and calibrated, and the scaling process of the method is simulated.Furthermore, the inversion errors of incident light with different polarization states when the main physical parameters of the instrument are deviated are analyzed, Azimuth angle, explicit polarizability, low frequency transmittance.A calibration experiment was carried out on the instrument, and the range of the main physical parameters of the instrument and its fitting And the relative error of the radiation calibration intensity caused by the deviation of the explicit polarizability parameter is further calculated to be 0.4%, which meets the requirement of 5% of the radiation accuracy of the instrument and leaves enough room for the study. High-precision radiation measurement, calibration and post-data processing provides a theoretical basis and experimental guidance.