新型双通道差分偏振干涉成像系统

针对Wollaston棱镜和Savart偏光镜(SP)组合的差分成像光谱系统存在光线溢出和无法改变系统光程等问题,设计了一种新型双通道差分偏振干涉成像系统.此系统不仅可获取正交偏振图像,还可以通过调整Savart偏光镜的厚度来改变系统光程.介绍了该系统的结构、理论原理,并利用琼斯矩阵推导出四束偏振光线的复振幅及其相干光干涉强度表达式.分析了宽视场Savart偏光镜(WSP)和可调光程的Savart偏光镜(MSP)的分束特性,得出WSP相较于SP具有更好的剪切能力和WSP可优化系统光路的结论.获得了不同楔形结构角下MSP的光程差、横向剪切量随楔形移动量的变化曲线.通过实验验证,获取了不同剪切量下的干涉图像和复色光下平行、垂直分量的空间图像,进而获得了总的强度图像和差分强度图像.得出差分强度图像相较于偏振强度图像具有较高对比度的结论.研究结果对双通道成像光谱系统的性能优化具有一定的参考意义.

Novel dual channel polarization interference imaging system

The interference images with fixed spectral resolution can be obtained by using the existing static polarization-difference imaging system because the optical path of the system cannot be changed flexibly. However, for different detection targets, the spectral resolution of the system determined by the optical path difference must be appropriate. To satisfy a variety of application requirements, a novel dual channel polarization-difference interference imaging system (DPDⅡS), based on the lateral shear of the wide-field-of-view Savart polariscope (WSP) and the modulated Savart polariscope (MSP), is presented. The two-dimensional space images of a target and orthogonal interference images can be obtained by adjusting the MSP under different lateral displacements simultaneously. In addition, the remarkable characteristics of the system avoid spilling over rays and optimizing the system optical path effectively. In this paper, by using the Jones matrix, the system structure is demonstrated and the theoretical principle of DPDⅡS is analyzed in detail. The amplitudes of the four beams from the MSP and the interference intensity expressions of the coherent light are derived. Then the splitting characteristics of the Savart polariscope (SP) and WSP are presented. It is concluded that the WSP has better shear ability than SP and the WSP can optimize the optical path effectively compared with Wollaston prism in the DPDⅡS. The change ranges of the optical path difference and lateral displacement produced by the MSP for structure angles α=π/3, π/4, π/6 are analyzed in detail. The reconstructed orthogonal interferograms and the experimental interferograms under 632.8 nm monochromatic light for d_MSP=1.00, 1.10, 1.20, 1.30 mm are obtained. A comparison between the experimental interference images and the simulated images proves that the interference fringes with different resolutions can be obtained simultaneously by adjusting the MSP. Meanwhile, the light intensities of the double optical paths are approximately equal and the same optical path difference is generated for the dual channel with the movement of MSP. The experimental results are consistent with the theoretical analyses. The spatial images of parallel and vertical components are detected under 632.8 nm polychromatic light. Then the total intensity image and the polarization-difference image are obtained through data processing. The conclusion that the polarization difference intensity image has a high resolution compared with the polarization intensity image is presented. The study has reference significance and practical value for the dual channel polarization interference imaging system.