Metrological Aspects of Laser Scanning System for Measurement of Cylindrical Objects

Abstract

In laser-scanning measurement of cylindrical objects the obtained fringe pattern is due to the superimposition of: reflected, unobstructed and scattered light. The proportions between these components vary in time and are affected strongly by instabilities of measuring system. The theoretical approach, based on Fresnel theory, leads to the conclusion that the existing solutions for diffraction of 3D bodies do not fit to engineering applications. Having the above in view, the close analysis of detector signal was carried out. The experiments concern: (1) warm-up time and stability of laser radiation, (2) the real structure of laser beam, (3) the influence of the active detector area on registered signal, (4) determination of the position of object edge in relation to the laser beam waist. The obtained results help to optimize the configuration of all interferometric laser measuring systems.