REVERSE ENGINEERING - HIGH-SPEED DIGITIZATION OF FREE-FORM SURFACES BY PHASE-SHIFTING GRATING PROJECTION MOIRE TOPOGRAPHY

A new digitization method is presented for automatic acquisition of ge ometric information on free-form surfaces for the sake of reverse engi neering. Principles of grating projection moire topography are utilize d with emphasis on enhancing the measuring resolution by incorporating phase-shifting fringe analysis, The measuring range and resolution ca n be readily adjusted to suit the object size to be measured, simply b y varying the spatial line pitch of the moire gratings. In addition, n o time-consuming beam scanning is required in the measurement, keeping the measuring time relatively low as compared with other existing tec hniques. Experimental results demonstrate that the three-dimensional c oordinate data of 640 X 480 points can be attained within 5 seconds ru n on an IBM PC 586, with measuring resolutions of 0.1 mm down to 0.001 mm. (C) 1998 Elsevier Science Ltd. All rights reserved.