Quan Chenggen, Fu Yu, Tay Cho Jui, Tan Jia Min
Department of Mechanical Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore.
Appl Opt. 2005 Jun 1;44(16):3284-90. doi: 10.1364/ao.44.003284.
A temporal wavelet analysis algorithm is proposed for shadow-moiré-based three-dimensional surface profiling on objects having discontinuous height steps. A grating is positioned close to an object, and its shadow is observed through the grating. The moiré fringe patterns vary when the grating is in-plane rotating. A series of fringe patterns are captured by a CCD camera at different rotating angles. Phase values are evaluated point by point with the continuous wavelet transform. From the phase values of each point on the object, the distance between the object and the grating can be retrieved. The surface profile is obtained without temporal or spatial phase unwrapping. This technique is applicable to objects with discontinuous height steps, which are impossible to measure with conventional shadow moiré topography. Two specimens are tested to demonstrate the validity of the method: One is an object with a height step of 1.6 mm, and another is a small coin with unevenness of less than 0.2 mm. The experimental results are compared with test results by use of the mechanical stylus method.
提出了一种基于时间小波分析的算法，用于对具有不连续高度台阶的物体进行基于阴影莫尔的三维表面轮廓测量。将一个光栅放置在靠近物体的位置，并通过该光栅观察其阴影。当光栅在平面内旋转时，莫尔条纹图案会发生变化。在不同的旋转角度下，由电荷耦合器件（CCD）相机捕获一系列条纹图案。利用连续小波变换逐点评估相位值。根据物体上各点的相位值，可以反演出物体与光栅之间的距离。无需进行时间或空间相位解缠即可获得表面轮廓。该技术适用于具有不连续高度台阶的物体，而这些物体用传统的阴影莫尔形貌法是无法测量的。测试了两个样本以证明该方法的有效性：一个是高度台阶为1.6毫米的物体，另一个是不平度小于0.2毫米的小硬币。将实验结果与使用机械触针法的测试结果进行了比较。
