对包络变化及移相误差不敏感的宽带光八步移相算法

Eight-step phase shifting algorithm for broadband light interferometry insensitive to envelop variation and phase shifting error

提出了一种用于测量微观表面三维形貌的宽带光八步移相算法。该算法通过定位宽带光干涉条纹的零相位差位置实现微观轮廓的测量。计算宽带光移相干涉信号中相邻采样点的相位差得到实际移相间隔,从而实现实际移相量的在线标定以及移相误差的校正。分析了倾斜Si C平面的移相干涉条纹,计算结果的标准均方差为1.646 nm,与不存在移相误差时的计算结果吻合。宽带光八步移相算法对干涉包络的变化不敏感,能够抑制移相误差,是一种实用、高精度的微观表面轮廓测量方法。

An eight-step broadband light phase shifting algorithm was proposed for the determination of three dimensional micro textures. The actual phase step was calibrated to eliminate the phase shifting error, from the difference between the phase values of two neighbored sampling of the broadband light interference signal. The microscopic interference fringes with phase shifting error of the oblique SiC flat were analyzed. The standard deviation is 1.646 nm, showing excellent agreement with the result obtained without phase shifting error. The proposed method, insensitive to envelop variation and phase shifting error of the interference signal, is practical and accurate for understanding three dimensional micro textures.