关键词: 相位展开, 三维面形测量, 傅里叶变换轮廓术, 虚拟相位平面, 高度重建

Abstract:

In order to accurately reconstruct the height of the tested object, phase unwrapping plays an important role in the three-dimensional (3D) shape measurement system based on phase analysis. The traditional phase unwrapping method often requires additional projected images, and/or needs a time-consuming 2D spatial phase unwrapping algorithm. Meanwhile, Fourier Transform Profilometry (FTP) only needs to collect one or two deformed fringe pattern to restore the 3D shape of the measured object. It is fast and easy to implement and suitable to measure the dynamic object. A new phase unwrapping method is presented in this paper, in which the phase order can be correctly retrieved from integer multiples of 2π and the phase different between the wrapped phase and the unwrapped reference phase. If the measured object is more complex, some virtual phase plane created by adding or subtracting 2nπ from the reference phase will be used to get the correct phase order. Finally, the natural continuous phase distribution of the measured object can be obtained from the combination of the multi-step phase unwrapping results. The feasibility of this method is proved by the results of simulation and 2 actual experiments. It is proved that this method is fast, no spreading error and can be efficiently used in the measuring system based on FTP method.

Key words: phase unwrapping, 3D shape measurement, Fourier Transform Profilometry, virtual phase plane, height reconstruction