Three Coordinates 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 value to height distribution and map the image coordinates to the global ones, which usually done by 3D calibration. It is the key process of 3D shape measurement cause of its relation of the measurement accuracy. Based on the dual-direction nonlinear phase-height mapping technique and Pinhole camera model, and considered the characteristic of Fourier spectrum of a linear structured signal, in this paper, a method which can complete the calibration of height (Z) and lateral coordinate (XY) simultaneously and perfectly by orientation filter is presented. This method has been used to successfully calibrate the measurement system of 3D shape and deformation of a rotating blade, its standard deviation is less than 0.27 mm in lateral coordinate (230×230 mm) and 0.022 mm in height (72 mm). This method can be used in 3D shape measurement instruments based on Fourier Transform Profilometry (FTP).