Schmidt棱镜偏振像差对成像质量的影响

Effect of Polarization Aberration on the Image Quality of Schmidt Prism

为了分析Schmidt棱镜偏振像差在自然光成像系统中对成像质量的影响,以线偏振光矢量衍射光强分布为基础,利用两种非相干叠加积分模型,获得了自然光通过Schmidt棱镜后完全相同的衍射光强分布关系。通过这个关系式分析得知,自然光经过屋脊棱镜的偏振像差表现为衍射光斑的对称分裂。对分裂导致的像面中心亮度比、分辨率以及所提出的像面变形度等像质评价参数进行了分析计算。结果表明,Schmidt棱镜的成像质量受到其偏振像差的影响严重。Jones矩阵因子B作为棱镜的结构特性参数,影响并决定棱镜的成像质量。B因子的大小就是Schmidt棱镜偏振像差的大小。理论分析及实验结果均表明,B=0为校正Schmidt棱镜偏振像差的一个条件。

In order to analyze the effect of Schmidt prism′s polarization aberration on the imaging quality with the widely used un-polarized light, based on diffraction intensity distribution of polarized light vector and by using two incoherent superposition integral methods, the same diffraction patterns as un-polarized light passing through the Schmidt prism are obtained. According to the equation of diffraction pattern, the polarization aberration consists of doubling of the image after the un-polarized passing through Schmidt prism and they are symmetrical. Analysis results of the central intensity ratio, resolution and the surface deformation defined in this paper show that the imaging quality of Schmidt prism is severely affected by the polarization aberration. B, one of the Jones matrix factors, as the structure characteristic of prism parameters, influences and determines the quality of imaging prism. The value of B indicates the size of polarization aberration of Schmidt prism. Both theoretical analysis and experimental results show that, the best condition for correction of Schmidt prism polarization aberration is B=0.