傅里叶变换轮廓术中相位失真的预矫正方法

Prior Correction Method of Phase Distortion in Fourier Transform Profilometry

介绍了一种基于傅里叶变换轮廓术的三维面形测量系统中相位失真的预矫正方法。由于投影系统和成像系统的空间三角位置关系、投影仪的发散照明和两套系统蕴含的光学畸变,投影一幅相位与空间坐标成理想线性关系的标准正弦光场,拍摄到的条纹相位和空间坐标不再呈线性分布,引起相位失真,甚至会影响系统测量精度。该方法借鉴反向条纹投影的思想,计算拍摄光场的非线性相位分布与理想的线性相位分布之间的关系,预先矫正,反算出一个新的待投影光场。实验结果表明这种方法能有效地减小该类相位失真所导致的测量误差,获得了更好的测量结果。

A prior correction method of phase distortion in the three-dimensional shape measurement system based on Fourier Transform Profilometry is introduced. A standard sinusoidal fringe pattern with ideal linear relation between the phase and space coordinate is projected onto the surface of a tested object where the deformed fringe pattern could be recorded by an im- age system from other view. In terms of trigonometric spatial information between the projection system and imaging sys- tem, divergent illumination and a certain optical distortion existed in both two systems, the relationship between the phase of deformed fringe and its corresponding space coordinates does not distribute linearly, which will bring about phase distortion, even effect the measuring accuracy. Inspired by the idea of reverse fringe projection in this method, after calculating the rela- tion between the nonlinear phase distribution and the ideal linear phase distribution and prior correction, a new projected fringe pattern could be obtained after inverse calculation. The experimental results demonstrate that the proposed method can effectively reduce measurement errnr~ Pml^od h,, ,~1.~ A;o.~,： .a ___ a