基于石英晶体的旋光色散原理,提出了一种测量石英晶体光轴方向厚度的光谱分析方法。利用光学矩阵方法对测量原理进行了分析,指出通过测量由两个正交的偏光镜和待测石英晶体所组成的系统的透射曲线就可以精确计算出待测石英晶体的厚度。在实验的过程中进行了误差分析,分析表明选取长的测量波段、低的扫描速度、短的响应时间和小的狭缝宽度都有利于提高测量精度,并从理论上证明所得厚度的精度高于电子数显千分尺的测量精度。利用三种不同的方法对两块不同厚度的石英晶体进行了测量,测量结果表明利用提出的方法所得厚度的精度可以达到0.1 μm,与理论分析的结果相一致。

A spectrometer method for determining the thickness of quartz plate along the crystal axis is presented based on the optical rotatory dispersion effect of the quartz. Its operating principle is analyzed by means of matrix formulation, and the result indicates that the thickness of the quartz plate along the crystal axis will be exactly obtained by accurate judgment of the transmission curve of a quartz plate sandwiched between two crossed polarizers. The error in the experiment is analyzed and it is found that the measuring accuracy will be improved by choosing longer wave band, lower scan speed, shorter response time and smaller slit width. At the same time, the theoretical analysis proves that the measuring accuracy of this method is higher than the digital micrometer's. In the end, two quartz plates with different thicknesses are measured by three different methods, respectively. It is shown that the accuracy of the tested thickness is 0.1 μm and is in good agreement with the theoretical prediction.