多角度偏振成像仪系统级偏振定标方法研究

系统级偏振定标是多角度偏振成像仪(Directional polarization camera, DPC)研制过程中的关键环节,对于提高大气气溶胶和云相态等定量化探测应用具有重要意义。结合矩阵光学和辐射度学理论,建立了多角度偏振成像仪偏振响应定标模型,对关键影响参量进行定标。采用大口径积分球参考光源和分视场测量方法,消除了光楔平板对DPC三检偏通道视场非一致性的影响,实现了高频和低频相对透过率的高精度测量。采用傅里叶级数的分析方法,建立全视场起偏度的测量模型,消除参考光源偏振方位角绝对位置引入的测量误差,实现光学系统偏振特性的准确测量。采用可调偏振度光源和大口径积分球辐射源,开展了偏振定标精度的比对验证实验和精度分析。测试结果表明,全视场偏振定标精度优于0.5\%,自然光状态下的偏振定标精度优于0.05\%,验证了宽视场偏振遥感器偏振辐射响应定标模型的合理性,说明该系统级偏振定标方法可满足宽视场光学偏振遥感器的高精度偏振观测科学应用要求。

System-Level Polarized Calibration Methods in Laboratory of Directional Polarization Camera

System-level polarized calibration is an important link in the development of directional polarization camera(DPC), which is of great significance for improving quantitative detection applications such as atmospheric aerosols and cloud phases. The polarization response calibration model is established combining with matrix optics and radiation theories, and key impact parameters are calibrated. An integrating sphere reference light source with large aperture and sectional viewing field measurement is used to eliminate the influence of the optical wedge plate on the non-consistency of the field view of DPC three partial channel, and high precision measurements of the high and low frequency relative transmittances are achieved. By using the Fourier series analysis method, the measurement model of the polarization degree of full view is established, and the measurement error introduced by the polarization azimuth absolute position of the reference light source is eliminated, which guarantees the precise measurement of polarization degree. The variable polarization light source and integrating sphere radiation source with large aperture are used for the comparison and precision analysis, the DPC full view polarization calibration uncertainty is better than 0.5\%, and the DPC measured polarization degree uncertainty under natural light is better than 0.05\%, which confirms the precision and reasonability of polarization remote sensor with wide field of view polarization radiation response calibration model. This system-level polarized calibration method can meet the requirements of high-precision polarization observation scientific application of wide field optical polarization remote sensor.