本文对晶体电光效应实验中偏振光干涉原理进行定量诠释. 借助折射率椭球和小角度近似，总结出会聚光入射下

相干级次与条纹位置和加载在晶体上的驱动电压之间的定量关系. 通过实验采集干涉条纹提取数据，验证了干涉级次和暗纹

与干涉中心距离平方的线性关系，不同驱动电压下，两者相关系数均高于0.99; 利用驱动电压和干涉级次的变化规律测得晶

体电光系数，与公认方法所获结果的误差约为1.45%. 本实验设计可加深低年级本科生对偏振光干涉理论知识的理解，丰富实

验内容.

The principle of polarized light interference is quantitatively demonstrated using experiment of

crystal electro-optic effect. With the help of index ellipsoid and small angle approximation，it is summarized that

inherent order of stripe under convergent incident light is depended on position of stripe and driving voltage loaded

on crystal. Extracting data from interference fringes，the linear relationship between the interference order and the

square of the dark pattern position is verified，in different driving voltages，the correlation coefficients are all higher

than 0.99; the electro-optic coefficient of crystal is measured by using the relationship between driving voltage and

interference order，the error of the result is about 1.45% compared to accepted method. The experimental design

can deepen the understanding of the theoretical knowledge of polarized light interference for junior undergraduates

and enrich the experimental content.