在利用正弦相位调制菲佐干涉仪进行测量时, 由于菲佐板及待测物体表面对入射光的多次反射而产生多光束干涉, 干涉信号的强度随相位变化不是严格的余弦分布。按照双光束干涉的算法进行相位信息提取, 会引入一定的误差。以正弦相位调制菲佐干涉仪纳米精度微小位移测量为应用背景, 分析多光束干涉情况下该干涉仪信号解调算法的误差, 进而对干涉仪的相关参数进行优化, 并通过误差补偿对测量结果进行修正, 有效减小了多光束干涉产生的影响。

In a Fizeau interferometer using sinusoidal phase modulation technique, the variation of interference intensity with optical path difference (OPD) does not follow a rigorous cosine behaviour any more. This is because the presence of multi-reflection between the reference plate and the surface under test leads to multi-beam interferences. If the interference signal is processed according to double-beam interference theory, non-ignorable measurement error can be produced. In this paper, a sinusoidal phase modulation Fizeau interferometer used to measure micro-displacement with nanometer precision is established. The measurement error caused by multi-beam interference is analyzed in detail. Some parameters of the Fizeau interferometer are optimized and the measurement results are corrected using error compensation algorithm, so that the influence of multi-beam interference is reduced effectively.