小波变换轮廓术在双频光栅条纹中的应用

Application of Wavelet Transform Profilometry in Bi-Frequency Grating Fringe

为了解决非连续物体三维面形测量中所存在的非连续相位解包问题,采用计算机生成的两频率之比为一无理数的电子光栅作为空间载频光栅条纹投影到待测物体表面。另外结合伽博小波变换分析的相位解调原理,在一幅变形双频光栅图像中分析得到两个频率各自所对应的包络相位分布,并且应用钟金钢等所提出的双频条纹查表法进行解包得到确定的调制相位分布。提出的双频光栅小波变换查表相位解包法很好地解决了傅里叶变换轮廓术,以及连续相位解包法在非连续物体三维面形测量中所存在的问题。给出了详细完整的理论推导过程、计算机模拟以及实验验证,证实了该方法的可行性。

In order to overcome the discontinuous phase unwrapping problems existing in the shape measurement of the discontinuous objects, the spatial carrier grating fringe pattern produced by the computer of which the ratio of two frequencies is an irrational number, is introduced. By using the wavelet transform profilometry, the wrapped phase distribution corresponding to the two frequencies respectively in one bi-frequency grating pattern is got. And then applying the phase unwrapping by a lookup table method for unwrapping, the determinate modulated phase distribution corresponding to the two frequencies is got. The technique can tolerate the height discontinuity of the shape of the objects. The detailed theoretical deduction, experimental verification and an example of 3-D shape measurement are shown.