一种基于PEM和EOM联合调制的波片参量检测方法

A method of wave plate parameter detection based on PEM and EOM

波片作为一种能改变入射光偏振状态产生相位延迟的重要光学元件,它的准确快速测量一直是研究的热点,为了解决波片参量检测灵敏度不足、速度慢的问题,提出了一种基于弹光和电光联合调制同时测量波片相位延迟量和快轴方位角的简单方法。在该方法中一个参考光路用于监测PEM的相位延迟量实现相位的稳定控制,另一个光路在PEM保持稳定后实现待测波片参量的检测,基于FPGA与数字锁相技术提取探测信号的倍频分量和直流分量,并在片上可编程系统中实现数据处理,从而快速高精度完成对波片相位延迟量和快轴方位角的检测。实验结果显示在PEM相位延迟量稳定在2.405 rad时,该系统检测波片的相位延迟量和快轴方位角的平均相对偏差分别为0.27%和0.25%。测量过程简单快捷、测量精度较高。

As an important optical element which can change the polarization state of incident light and produce phase delay,wave plate has been a hot research topic for its accurate and rapid measurement.To solve the problem of insufficient sensitivity and slow speed of wave plate parameter detection,a simple method based on photo-elastic modulator(PEM)and electro-optic modulator(EOM)for simultaneous measurement of phase retardation and fast-axis azimuth angle of wave plate is proposed.In this method,one reference optical path is used to monitor the phase retardation of the PEM to achieve phase stabilization control,and the other optical path is used to detect the parameters of the wave plate to be measured while maintaining the PEM stability.The double frequency component and the direct current component of the detection signal are extracted based on FPGA and digital phase-locked technology,and the data processing is realized in the on-chip programmable system,thus the phase retardation and fast-axis azimuth angle of the wave plate are detected with high speed and high precision.The experimental results show that when the PEM phase retardation is stable at 2.405 rad,the average relative deviation of phase retardation and fast-axis azimuth angle of the system is 0.27%and 0.25%respectively.The measuring process is simple and quick,and the measurement accuracy is high.