航空偏振相机的光学偏振特性实验研究

Experimental study for the polarization characteristics of airborne polarization camera

利用大孔径积分球辐射光源系统对航空偏振相机的偏振特性进行了实验研究,以各偏振工作波段中0°放置的偏振通道为基准,选取航空偏振相机中心视场64×64像素点计算并校正了各偏振通道中偏振片/滤光片的强度透过率差异;并进一步测量了航空偏振相机光学系统自身的起偏度,通过最小二乘法多项式拟合,给出了各偏振工作波段的偏振度随视场角的拟合函数。该实验的数据图像处理方法具有统计特性,可以消除光学元件部分缺陷及CCD探测器异常响应噪声对拟合偏振度曲线的影响。结果表明,偏振相机不同偏振通道的起偏特性不同,并且随着视场角的增加而变大。

This paper studies experimentall the polarization characteristics of airborne polarization camera based on the large-bore integrating sphere. The relative intensity transmission coefficients of the instrument polarizers and filters in all polarized spectral channels are given based on the 0° polarizer angle channel at the center of the CCD matrix 64 × 64 pixels. The degree of polarization variation of optical system in airborne polarization camera is analyzed by measuring the non-polarized radiance from the integrating sphere, and a fitted polynomial function of degree of polarization relating all viewing directions within the instrument field of view is presented. The flaws of optical components and the abnormal noise of the CCD detector have little influence on the fitted function because of the statistical treatment with the whole field of view of the airborne polarization camera. Experimental study shows that the polarization characteristics for different polarized spectral channels are variant, and the airborne polarization camera often has bigger degree of polarization at larger field of view.