基于锁相技术和磁光调制的旋光角度检测

摘要

According to Faraday effect and lock-in amplification principle,the magneto-optical modulation of polarized light through an optical material occurs after deflection.The output light contains a fundamental signal and a frequency-doubled signal whose frequencies are equal and doubled to modulation frequency respectively.Based on the analyses of amplitudes of fundamental and frequency-doubled signals,we put forward an algorithm for measuring the rotation angle. According to the relation between optical rotation angle and magnetic declination,we put forward a method to calibrate the magnetic declination in the Faraday magneto-optic effect.The feasibility of such measurement approach has been verified by our experiments.%根据法拉第磁光效应和锁相基本原理，研究了经磁光调制后的偏振光通过旋光物质后的偏转情况，分析了透射光信号中的与调制频率相同的基频信号和二倍于调制频率的倍频信号。通过对基频幅值和倍频幅值进行比较，提出了一种测量旋光角度的计算方法，根据旋光角和磁偏角两者之间的关系，提出了一种用标准石英管来标定法拉第磁光效应中磁偏角大小的方法，并对其进行了实验研究，证明了这种测量方法的可行性。