采用双调制方式测量消光比参数

Measurement of extinction ratio by dual modulation

提出了一种采用磁光调制与光源调制技术高精度测量偏振棱镜消光比参数的方法并建立了相应的消光比测量系统。首先,根据偏振光的琼斯矩阵描述方式推导了系统的测量模型;采用磁光调制方式,实现了待测偏振棱镜晶体光轴与起偏器晶体光轴夹角的高精度定位。然后,采用光学斩波器对光源进行方波调制,消除了各种噪声对系统测量精度的影响,使得系统在待测偏振棱镜实现光轴精确定位后能够准确测量光强值。最后,对待测偏振棱镜进行了多次测量并求取平均值。实验结果显示,对偏振棱镜消光比参数的测量精度为10-6,验证了提出方法的有效性和稳定性。该系统精度高、稳定性好、容易实现工程化,对偏振器件的性能检验和实际应用具有指导意义。

A method by using magneto-optical modulation and light source modulation techniques was proposed to measure the extinction ratio of a polarizing prism precisely, and an extinction ratio meas- urement system was also established based on the two modulation techniques. Firstly, the system＇s measurement model was derived according to the Jones matrix describing manner of polarized light. By using a magneto-optical modulator, the optical axis angle between a polarizer and a measured polari- zing prism was precisely located. Then, by using a chopper to modulate the square wave of a light source, the impact of noises on the system measurement accuracy was eliminated and the system could measure the light intensity value accurately after the measured polarizing prism＇s axis was located pre- cisely. Finally, the polarizing prism was measured for a number of times and the data were averaged. The experimental results indicate that the measurement accuracy of extinction ratio for the polarizing prism can be 10^-6, which verifies the effectiveness and stability of the method. The system is charac terized by high stability, high accuracy, and can offer the references for the performance test and engi- neering applications of polarized devices.