Design of an Optical Proximity Sensor Using Multiple Cones of Light for Measuring Surface Shape

摘要

A noncontact multi-light source optical proximity sensor which can measure the distance, orientation, and curvature of a surface has been developed. Beams of light are sequentially focused from the ends of fiber optic cables onto a target surface. An analog light-sensor- a planar PIN diode area sensor chip - measures the position of the spots of light on the surface, and the 3-D locations of the spots are computed by triangulation. By fitting a surface to a set of points, the distance, orientation and curvature of the target surface is calculated. The number of light sources, and their positions and orientations were chosen so that the uncertainty in the measurement of distance would be within 0.05 mm and the uncertainty in surface orientation would be within 1.0 deg. Since there are no moving parts and the spot position sensor chip outputs the position of the spot directly without scanning its field of view, fast operation of the proximity sensor can be realized. Earlier prototype versions of the sensor can give approximatley 1000 measurements of distance and 1.5 degrees for surface orientation. This proximity sensor will be useful for such applications as tracing an object surface by a robot manipulator with a specified distance and orientation relative to the surface. (Author)