研究了随机电磁光源辐射光束的偏振度的轴向演化规律和在垂轴截面内的分布情况, 探讨偏振度传播规律的主要影响因素, 并发现存在相干性和偏振度以外的其他因素影响辐射的偏振性质。以高斯-谢尔模型光源为例, 导出了其谱相干度、偏振度和交叉偏振度与光源各参数依赖关系的解析表达式, 在此基础上指出具有相同相干性和偏振度的一组光源可具有不同的交叉偏振度。针对相干光源和非相干光源两种情况, 各计算了一组光源的辐射场偏振度随传播距离的变化曲线及其在与光束轴垂直的横截面内的分布情况, 结果表明, 在交叉偏振度中出现的光场两垂直分量间相关系数可显著影响辐射光束偏振度纵向变化规律。

The effects of source cross polarization on the polarization degree of radiation beam were investigated. Formulas expressing the spectral degrees of coherence, of polarization and the degree of cross polarization of a Gaussian-Schell-model source were analytically derived. From these formulas it was demonstrated that sources with the same set of degrees of coherence and polarization may have different degrees of cross polarization. The spectral degrees of polarization as a function of the distance from the source were calculated for coherent and incoherent sources respectively. The plots show that the correlation coefficients between the two mutually orthogonal components of sources may evidently affect the longitudinal evolution and the asymptotic values of the polarization degree.