Development of Range Sensor with Circular Scanning

ORANGES System

Abstract

This paper describes the prototype of an optical range sensor with circular scanning of a beam spot and its fundamental characteristics. The prototype sensor: ORANGES system whose name is an abbreviation of an Optical RANGE Sensor system provides with a function of an optical range sensing at each point sequentially along a circular path, which is a locus on the surface of an object generating by the circular scanning of a beam spot.
ORANGES system is made up by both mechanisms of generating the circular scanning of a laser beam spot and measuring distance to it. The former mechanism is provided for the projection of a laser beam spot onto the surface of object along the circular path. The latter mechanism is constructed by four devices with a collecting cylindrical lens mounted on the PSD sensors at perpendicular intersection each other. Each device is capable of detecting the x or y axis components of a distance from the displacement of the image of a light spot on each PSD sensor by triangulation. The range data are taken from the two devices which are selected by the combination of the x and y axis components in the four devices. Moreover, ORANGES system is capable to do the range sensing from four different directions to the same laser beam spot.
The experimental results confirm the accuracy of range as less than ±0.2 [mm] (±3σ, σ: standard deviation, in a dark room) in the range of 30-60 [mm] and also ±2.0 [mm] (±3σ) in the range of 60-100 [mm].