组合波片的椭圆率角测量方法

为精确测试组合波片的椭圆率角，提出了一种基于Mueller矩阵的椭圆率角测量方法.建立了组合波片的偏振模型，通过测量其Mueller矩阵，利用非线性拟合同时获得相位延迟、快轴方位和椭圆率角3个参数，并利用Mueller矩阵椭偏测量系统分别计算测量了λ/4和λ/2组合零级波片，结果表明基于此方法的拟合误差在0.004以内，椭圆率角和快轴方位角的测量误差为0.11°，相位延迟的测量误差为0.22°.通过本方法还发现组合零级波片的椭圆率角和快轴方位随波长震荡，λ/4和λ/2组合零级波片的震荡幅度分别为1°和0.4°.本方法适用于任意组合波片的椭圆率角测量，应用范围广. 

Method for Measuring Ellipticity Angle of Composite Waveplate

In order to accurately measure the ellipticity angle of composite wave plates, a method was proposed based on Mueller matrix. Firstly, a polarization model of the combined wave plate was established. Then, by measuring its Mueller matrix, three parameters, including retardation, fast axis azimuth and ellipticity angle were obtained simultaneously with non-linear fitting. Finally, the ellipticity angles of the combined zero-order wave plate with λ/4 and λ/2 were calculated and measured respectively by using the Mueller matrix ellipsometry system. The results show that the fitting error based on this method can achieve within 0.004, and the ellipticity angle and fast axis can achieve within 0.004. The measurement error of azimuth angle is 0.11° and that of phase delay is 0.22°. It is also found that the ellipticity angle and fast axis azimuth of the combined zero-order wave plate oscillate with wavelength, and the oscillation amplitudes of the combined zero-order wave plate are 1° and 0.4° respectively. This method is suitable for ellipticity angle measurement of arbitrary combined wave plates and has a wide application range.