傅里叶磁光谱仪中的起偏器和检偏器的自动定位及误差分析

在傅里叶变换型磁光谱仪中，起偏器和检偏器的初始方位通常需要在测量前预先定位。提出了一种不需要专门对起偏器和检偏器定位即可完成磁光谱的测量计算的新方法，该方法可以计算出起偏器和检偏器的初始角度值，从而进行自动校准。推导了检偏器旋转角度偏差导致磁光偏转角测量误差的理论公式，并进行了数值分析，给出了测量误差与旋转步数的关系，数值结果表明检偏器角度偏差引起的误差与步数的平方根成反比关系。还给出了一个钴膜样品的磁光克尔角随外加磁场变化的实测曲线。

Auto-Alignment of Polarizer and Analyzer and Error Analysis in Fourier Magneto-Optic Spectrometry

In conventional Fourier-type magneto-optic spectrometer, the starting azimuth angle of polarizer and analyzer should be determined and aligned before the measurements. A novel method for the auto-alignment of polarizer and analyzer is proposed. The magneto-optical rotation angle can be measured and calculated without knowing the starting positions of polarizer and analyzer. The starting positions of polarizer and analyzer are computed during the measurement and can be automatically aligned. A formula of magneto-optical rotation angle error resulting from the positioning deviation of analyzer is derived, which gives a inverse proportional relation between measuring error and the square root of step number of rotating analyzer through a revolution. Numerical simulation is presented to demonstrate the theoretical analysis. As an example, the magneto-optical Kerr angle of Co films as a function of strength of magnetic field is given.