采用单波长反射式椭偏仪以及多次旋转样品的方法,实现了光轴平行于表面的各向异性晶体光学参数的测量。分析了单波长椭偏法测量各向异性晶体光学参数的原理,改进了模拟退火单纯形联合反演算法,利用数值模拟讨论了光入射角、样品光轴取向、旋转角度及其定位误差对测量结果的影响。实验结果表明,该方法测量晶体的主折射率、吸收系数及光轴方位角的精度分别为0.0001~0.0003、0.000001~0.000400、0.02°~0.40°,具有较好的自洽性和准确性。

The optical parameters of anisotropic crystal, with optical axis parallel to surface is measured by employing a single-wavelength reflective ellipsometer and method of rotating the sample many times. The principle of measuring the optical parameters of anisotropic crystal by single-wavelength ellipsometer is analyzed, the simulated annealing simplex joint inversion algorithm is improved, the influence of the light incident angle, sample optical axis direction, rotation angle, and positioning error on the measurement results are numerically simulated and analyzed. Experimental results show that the measurement accuracy of the main refractive index, absorption coefficient, and optical axis azimuth angle of the crystal are 0.0001-0.0003, 0.000001-0.000400, 0.02°-0.40°, respectively, which indicates the method has high self-consistency and accuracy.