An accurate 3D inspection system using heterodyne multiple frequency phase-shifting algorithm

This paper presents an accurate 3D inspection system for industrial applications, which uses digital fringe projection technology. The system consists of two CCD cameras and a DLP projector. The mathematical model of the 3D inspection system with 10 distortion parameters for each camera is proposed. A heterodyne multiple frequency phase-shifting algorithm is employed for overcoming the unwrapping problem of phase functions and for a reliable unwrapping procedure. The redundant phase information is used to increase the accuracy of the 3D reconstruction. To demonstrate the effectiveness of our system, a standard sphere was used for testing. The verification test for the 3D inspection systems are based on the VDI standard 2634. The result shows the proposed system can be used for industrial quality inspection with high measurement precision.