傅里叶变换轮廓术中三维坐标同时校准方法

在相位测量型光学三维面形测量中,最终都要将相位信息转换成被测物体的高度分布信息,这个过程往往是通过对已知世界空间坐标的特征点事先标定,获得测量系统的内外特征参数后,完成被测物体的三维坐标转换.因此,标定是三维面形测量的关键环节.本文基于双向二次相位-高度映射方法和摄像机针孔模型线性无畸变标定技术,充分利用傅里叶变换的频谱方向特性,提出了对含有特征点的二维标定物表面变形条纹的频谱进行方向滤波操作,同时获取测量系统XYZ三个方向上的标定数据,对测量系统进行立体校准的系统标定方法.结合旋转风扇叶片形变的测量系统,给出了该方法的标定结果:在XY面内(230mm×230mm)的标准偏差小于0.27mm;在Z方向上小于0.022mm,位移测量灵敏度优于0.05mm.该方法为测量系统的实用化奠定了基础.

Phase-height Mapping and Coordinate Simultaneous Calibration in Fourier Transform Profilometry

In three-dimensional (3D) shape measurement based on phase measuring, the ultimate and important job is to map the phase to height and map the image coordinates to the global ones, which are usually done by 3D calibration. It’s a key process because of its relation to the accuracy of the measurement. Based on the dual-direction nonlinear phase-height mapping technique and the Pinhole camera model without lens distortion, and considered the characteristic of Fourier spectrum of a linear structured signal, a method which can complete the calibration of height (Z) and the lateral coordinates (XY) simultaneously by orientation filter is presented. The method has been used successfully to calibrate the system of rotating blade measurement, its standard deviation is less than 0.27 mm in the lateral coordinates (230 mm× 230 mm) and 0.022 mm in height (72 mm). 3D calibrations can be easily and perfectly done with the method.