Three-dimensional whole circumference shape measurement system using optical patterns projection technique

Abstract

An automatic three-dimensional whole circumference shapes measurement system using an optical patterns projection technique has been developed. The system is composed of an optical spatial modulator from which grating patterns are projected on the surface of the object set on a turntable stage, a CCD camera controlled by a robot arm, and a computer. The patterns on the surface of the object are taken into the computer by the CCD camera, and the three-dimensional coordinates of the patterns on the surface of the object are calculated according to a principle of a trigonometry measurement. The patterns faced to the CCD camera are taken into the computer by the CCD camera, four photographs at each turntable angle of 0, 90, 180, and 270 degrees are processed and the image processing data are composed as whole circumference shapes. This improved system using mechanical and optical method and data analysis has the following advantages. (1) It is possible to capture the surface topography without any contact. (2) The time required for the measurements is shorter than the light-section method. (3) The optical spatial modulator using a liquid crystal projector enables to control the striped patterns accurately by the computer. (4) It is possible to measure precisely and to expand the measurement area using a zoom camera. (5) The improved system has whole circumference shapes measurement area as well as high resolution.