Calibration and analysis of eccentric error of the laser rotary-scanning measurement system

A laser rotary-scanning measurement system was developed for the reverse engineering of 360° objects. The system is constructed by an optical head and a rotary indexing. The optical head is composed of a laser diode strip-light projector and dual CCD cameras. Based on the principle of structured-light triangulation, a laser line is projected onto the object upon which the distorted line is captured by dual CCD cameras from left and right simultaneously. By processing a series of line fittings from the discrete angular positions of an object, the entire 3D profile can be reconstructed. Since the actual space coordinates of the object are computed according to the geometric relationship between the coordinate of optical head system and the coordinate of the rotary indexing systems, if these two coordinate systems are not in good alignment, errors in the computed coordinates will be introduced.This paper describes the influences of the alignment and eccentricity errors of the laser rotary-scanning measurement system on the computed geometrical profile. Calibration procedures are then proposed to adjust the alignment to avoid image distortions and thus enhance the system accuracy. Experimental results show that this easy-to-use calibration procedure can significantly improve the accuracy of the system.