双轴晶体会聚偏光干涉的理论与实验研究

Theoretical and Experimental Study on the Interference of Convergent Polarized Light for a Biaxial Crystal

晶体会聚偏光干涉图包含了晶体特性的许多信息,建立偏光干涉图的定量分析方法可以使这些信息得到充分利用。基于双轴晶体折射时满足的波矢关系,导出了两折射光波相位差的精确计算公式。分析了光波在各界面折射时偏振态的变化,提出了会聚偏光干涉合成振幅的计算方法。针对任意取向的双轴晶体,计算了完整的偏光干涉图,反映了相位分布决定等色线、振幅分布决定消光影的规律。用数字图像模似了干涉图,并讨论了干涉图的变化情况。对4块不同取向的KTP晶片进行实验,实验干涉图与理论干涉图的特征完全一致,两者仔细对比可判断现有KTP晶体色散方程的优劣。

Many important information of a crystal is included in the convergent polarized light interference pattern, and can be completely utilized by numerical analysis of the pattern, Based on the relationship of wave vectors on.crystal interface, accurate formulas calculating phase difference between two refracted waves are deduced. Changes of light polarization in each interface are analyzed and the method to calculate total amplitude in convergent polarized light interference is proposed. The conoscopic interference patterns of crystals are calculated for any orientation biaxial crystal, which include information of isochromatic curve and isogyre. The interference patterns are simulated by digital image and the changes of the patterns are discussed. Experiment of the conoscopic interference is completed for four pieces of KTP crystals with different orientation, Comparison of the experimental patterns and theoretical patterns can judge which Sellmeier＇s equation is best.