为了分析胶合剂折射率对Glan-Thompson棱镜性能的影响, 采用理论分析的方法, 得出棱镜视场角以及光正入射和斜入射时棱镜的透射比与胶合剂折射率的关系式。在此基础上, 针对几种确定长度孔径比的Glan-Thompson棱镜, 利用计算机拟合, 取得棱镜视场角及透射比随胶合剂折射率变化的关系曲线, 并进行了实验验证。结果表明, 对于不同长度孔径比的棱镜, 最大视场角不同, 且对应不同的胶合剂折射率值;胶合剂折射率等于e光的主折射率时, 棱镜有最大透射比;由于棱镜的长度孔径比、最大视场角、透射比以及胶合剂折射率之间有相互制约的关系, 采用长度孔径比为2.5的棱镜设计和折射率为1.45～1.46的胶合剂是一种较佳的方案。这一结果对优化Glan-Thompson棱镜的视场角和透射比是有帮助的。

In order to analyze effect of refractive index of cement on a Glan-Thompson prism, the field angle of the prism and the relationship between the transmittance of the prism and refractive index of the cement at normal incidence or oblique incidence were obtained after theoretical analysis. On this basis, for several Glan-Thompson prisms which the ratio of length to aperture was determined, the relation curve of field angle and transmittance with the change of refractive index of cement was drawn by means of computer simulation. It is found that with the different ratios of length to aperture, the maximum field angle of the prism is different corresponding to different refractive index of cement. The prism has the maximum transmittance when refractive index of the cement is equal to the main refractive index of e light wave. Due to the mutual restraint relationship of the ratio of length to aperture, the largest field angle, the transmittance and the refractive index, It is optimum when the ratio of length to aperture is 2.5 and the refractive index of the cement is in the range from 1.45 to 1.46. The result is helpful for optimizing the field angle and transmittance of a Glan-Thompson prism.