Patent ID: 7030365
Filing Date: 2006-04-18
Classification: G01V

Abstract:
1. An object detection system comprising a retroreflector; and a emitter-detector assembly having a light emission area from which a light beam is emitted toward the retroreflector and having a light detection area in which light impinging thereon from the retroreflector produces an electrical signal, wherein the light emission area and the light detection area are concentric with one extending around the other; wherein the object detection system has a quality factor Q that is greater than 0.25, where the quality factor is given by the expression: in which Rs is a signal produced by the emitter-detector assembly in response to returned light from a retroreflector, Srf is the size of the field of view in steradians of the light detection area, and Srr is the size in steradians of the light beam that is subtended by the retroreflector, Rd is the signal produced by the emitter-detector assembly in response to returned light from a 100% uniformly diffuse surface, and Gmax is a maximum reflectance of the retroreflector compared to light returned from a 100% uniformly diffuse surface.