A pseudo-interferometric laser range finder for robot applications

A description is given of a low-cost laser ranger suitable for robot applications. The region to be observed is illuminated by a sinusoidal intensity distribution generated by an optical projection system with a laser source. The deformation of the sine-wave pattern is detected by a phase-sensing method widely used in optical interferometry, and can be easily related to the shape and range information. Over a range determined by the depth of field of the camera at a given aperture and focal setting, high-resolution measurements can be made. Experimental results show that at a camera distance of about 1 m, the resolution and repeatability in locating a flat 25-mm² surface are of the order of 0.2 mm