提出一种空间相关实时相移标定方法,用于解决存在振动和空气扰动等干扰因素情况下,相移条纹图难以准确采集和相移器的非线性对相移精度的影响问题。分析了该方法的原理和使用条件,比较了与傅里叶标定方法间的异同。实验中通过对相移器不间断驱动,使存在干扰的干涉条纹相位呈单调变化,利用两幅条纹图采集存储的时间间隔插入一维空间相关计算,实时计算出所采集条纹图与参考图之间的相关系数及其与指定的相移量余弦值之差,差值最小时得到与指定相移量最接近的相移条纹图。实验结果表明,该方法适合在稀疏等间距干涉条纹下使用,实现方法简单,运算量小,实时性强,相移器的非线性对标定结果不会产生影响,即使存在一定干扰,也能准确实时标定出相移量。

In phase-shifting metrology, the accuracy of phase measurement is directly affected by the phase-shifting error, especially under existence of the circumstance of vibration and air turbulence, the expected value of phase shifting is hard to obtained. In this paper, a real-time high accuracy phase-shifting calibrating method based on one-dimensional spatial digital correlation is presented. In the experiment, the phase shifter is driven continuously to make the phase of interference fringes to change monotonously. By the use of the interval between the captured interference patterns to do one dimensional spatial correlative operation, the correlative coefficient and the cosine phase shifting difference between the captured interference pattern and the referenced interference pattern, and the expected value of phase shifting, can be real-time obtained, and the expected phase-shifting pattern is that with the minimum difference of phase shifting. The experiment result shows that the proposed method can be suitable for the phase measurement of the thin uniformly-spaced interference fringes. Even if the external turbulence exists, the result of phase-shifting calibration is not affected by the nonlinear of phase-shifter.