基于法拉第调制的线偏振光旋转角检测技术

Measurement of linearly polarized light rotation based on Faraday modulation

分析了基于法拉第调制的线偏振光旋转角检测技术的基本原理,证明输出信号基频分量的振幅与偏振面旋转角θ成正比,仿真发现基频分量远小于零频和二倍频分量,需采用锁相放大技术进行基频信号提取。实验采用ZF7玻璃和TG28晶体作为旋光介质,分别制作了标准旋转角产生装置和偏振面调制装置,并结合锁相放大器搭建偏振光旋转角检测系统。实验结果证明,当法拉第调制频率为1.45kHz、调制幅度为0.035rad时,该方法可以实现6.3×10-8rad的微小偏转角检测。

The principle of linearly polarized light rotation based on Faraday modulation is analyzed.The results indicated that the output amplitude of fundamental frequency component is proportional to optical rotationθ.But the fundamental frequency component,which is less than zeroth-order and second-order frequency component,need be extracted by lock-in amplification technique.The ZF7 glass and TG28 crystal are used as the standard optical rotation and polarization modulation devices.The measurement system of linearly polarized light rotation is built by a lock-in amplifier.When the modulation frequency is 1.45 kHz and modulation magnitude is 0.035 rad,the experimental results show that the method can examine the angle of 6.3×10-8rad.