3D Surface Profile Measurement of Moving Object Using Linear Sensors(Optical Method 2)

Abstract

A new method for measurement of the three dimensional surface profile and the deformation of continuously moving objects is proposed. A grid pattern made of an interference of plane wave is projected on a moving object. The deformed grid patterns projected on an object are acquired by three linear sensors continuously. Since a liner sensor records the light intensity on a single line along the original (reference) grid pattern, the result of the image forms a moire fringe pattern showing a profile of the object, like a scanning moire method. Using three images obtained by three linear sensors, the phase distribution of the moire fringe pattern is calculated by a phase-shifting method. The phase of the moire fringe pattern is simply proportional to the height of the object. This method can be used for not only the inspection of moving products on a belt conveyor but also health monitoring of huge structures, such as a tunnel from a moving train. The principle, and the accuracy of the proposed method are described in this paper. A simulation and an experiment for evaluating effectiveness of this method are explained.