Optical Sensing Techniques For 3-D Machine Vision

Active optical vision systems rely on the analysis of images on an object illuminated by known structured optical patterns. Approaches differ by the choice of projected pattern (dots, stripes, grids, etc.) and the type of analysis used to extract shape information. A novel approach is reviewed, whereby a sinusoidal grating structure is projected onto an object, and the resulting deformed grating images are detected by a solid state array camera and analyzed by a microcomputer using digital interferometric phase-measuring algorithms. Large arrays of data points can be acquired and processed in parallel with very high accuracy and speed. Two systems are described, one that yields range measurement from a single point of view over a two-dimensional array of points, and a second that permits full 360 degree measurement. The case of parallel laser light illumination, as well as that of general white light diverging illumination are described. Experimental results and performance analysis are presented.