液晶光谱偏振系统选偏器方位误差研究

Misalignment errors of polarizer in the liquid crystal spectropolarimetric system

为了分析液晶光谱偏振系统的方位误差并降低测量误差,提出了选偏器方位误差的分析方法。该方法基于Stokes矢量及Mueller矩阵,将偏振角的方位误差转化为Stokes矢量传递误差,推导了误差的协方差矩阵,分析了权重系数与延迟相位的变化关系,并对不同偏振态入射光条件下的品质因数变化进行了计算仿真。方位误差依赖于入射光Stokes参数与延迟相位,不同偏振态的入射光品质因数随延迟相位成抛物线变化。当延迟相位位于[60°,120°]区间内,选偏器的方位误差较小,测量误差较小适宜测量。通过对液晶偏振光谱系统配准误差的研究,获得误差来源,为进一步提高系统测量精度奠定了理论基础。

In order to analyze the misalignment errors of the liquid crystal spectropolarimetric system and reduce measurement errors, a research method for misalignment errors of liquid crystal polarizer is proposed. By transforming the misalignment errors of polarizing angle into Stokes vector transfer errors, the errors covariance matrix is derived based Stokes vectors and Mueller matrix. And the rela- tionship between weight coefficients and phase delay and the change of quality factor with different in- cident light are investigated. The reached conclusion is that azimuth errors depend on Stokes parame- ters of incident light and phase delay and quality factors are parabolic with different incident polariza- tion state. When delay phase locates in [60°, 120°], the azimuth errors of polarizer are lesser, which is more appropriate to measure. By investigating the misalignment errors of the liquid crystal spectropo- larimetric system, the error sources are obtained which can lay the foundation for measuring accuracy enhancement.