基于虚拟相位平面的相位展开方法

在基于相位分析的三维测量系统中,为了准确地得到物体的高度,相位展开扮演着很重要的角色。传统的相位展开方法常常需要额外的投影图,而傅里叶变换轮廓术只需要采集一幅或两幅变形条纹图就可以实现对物体轮廓的测量,其方法速度快,易于实现。针对傅里叶变换轮廓术方法计算得到的截断相位分布,本文提出了一种利用截断相位与参考平面相位差值2π的整数倍数获得截断相位的正确级次,辅助相位展开的方法。当被测物体较复杂,或者相位截断次数较多时,该方法在已有参考平面相位的基础上虚拟新的相位平面,依次比较截断相位和虚拟相位,进行多次分级相位展开,结合多个展开相位结果,最终得到正确的展开相位。该方法展开速度快,展开错误不会蔓延传递。仿真和实物实验结果证明了该方法的可行性,说明该方法可用于傅里叶变换轮廓术中进行截断相位的快速展开。

Phase Unwrapping Method Based on Virtual Phase Plane

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.