法拉第旋转角测量的同相检测法

The In-phase Measurement of Faraday Rotary Angle

提出了利用同相检测实现精确测量法拉第旋转器旋转角的方法。通过1个起偏器和1个偏光分束镜,利用光矢量方向与偏光分束镜主平面间夹角φ为45°实现对法拉第旋转角的测量。理论分析表明,当测量精度给定时,对探测器的光强灵敏度的要求比φ为90°的消光法要低数个数量级。

The measurement precision of Faraday rotary angle was generally determined by the power sensitivity of detector and the precision of dial on polarizer in extinction method.The in-phase measurement of Faraday rotary angle was given,which utilizing a splitting-polarizer and equal light intensity detection in two optical paths.Based on Malus′law,When the polarizing angel approached 45°,difference of the two light intensities was extremely sensitive to change of the polarizing angle and was close to zero,so the power sensitivity of detector can be utilized sufficiently.In this measurement,the measurement precision of Faraday rotary angle was decided mostly by the precision of dial on polarizer,and was more precise than in extinction method.