Patent ID: 6256016
Filing Date: 2001-07-03
Classification: G06F

Abstract:
An optical detection system for use with a surface, the system comprising:a coherent light source for producing a coherent light beam the coherent light beam to generate an illumination spot on the surface, for reflecting an image of the illumination spot;an optical sensing assembly, having a photosensor array and an optical element, for receiving the image of the illumination spot through said optical element and for generating a speckle image on said photosensor array; anda speckle image motion detection system for detecting movement of the speckle image, the speckle image motion detection system including a cross-correlation module for calculating movement of the speckle image relative to two directions,wherein the optical element includes an artificially limited anisotropic aperture having an aspect ratio, N, where N comprises the aperture along two directions.