利用分光光度计测量光学晶体的折射率

Measurement of Refractive Index of the Optical Crystal with Spectrophotometer

晶体折射率的准确测定是晶体上薄膜器件设计的基础。介绍了利用分光光度计测量晶体折射率的方法,通过背面影响系数法、背面镀增透膜和将两者结合起来的方法消除晶体反射率测量时背面反射带来的影响,给出了具体的步骤并对测量误差进行了分析。由于晶体的光学各向异性,采用起偏器扫描的方法测量晶体光学性质随方向的变化。通过对LiB3O5晶体的折射率的测量,证实了该方法的可行性并可用于其他光学晶体折射率的测量。

Design of thin film devices on the crystal is based on the accurate determination of crystal refractive index. Methods for measuring the refractive indices of crystals with spectrophotometer are introduced in this paper. The backside reflection effect is elimilated by means of backside influence coefficient, AR （antireflection） coating on backside, and combination of the former two when measuring the reflectance of the crystal. Specific steps are given and measurement errors are analyzed. The reflectance or transmittance change with propagation direction can be obtained using polarizer scanning due to the optical anisotropy of the crystal. The feasibility of the methods introduced is proved by measuring the refractive index of LiB3O5 crystal plate, and showing that the methods are used for measurement of the optical crystals.