Patent ID: 6786899
Filing Date: 2004-09-07
Classification: A61B

Abstract:
A position-detection apparatus for tracking eye movement comprising:a light source configured to produce a single infrared illumination beam projected onto an artificial reference affixed on an eye to be tracked, wherein said infrared illumination beam is projected near the visual axis of said eye and has a beam spot size on said eye greater than said reference and covering an area within which said reference moves with said eye, and wherein said reference has a retro-reflective surface producing backward scattering many orders of magnitude stronger than that from the tissue of said eye; an optical collector configured and positioned at a distance from said eye to collect backward scattered infrared light from said reference to form a bright image spot of said reference at a selected image location, wherein said bright image spot appears at said selected image location over a substantially dark background; a single-element positioning detector positioned at said selected image location to receive said bright image spot and configured to measure a two-dimensional position of said bright image spot of said reference on said positioning detector; and an electronic circuit coupled to said positioning detector to produce positioning signals indicative of a position of said reference according to a centroid of said bright image spot based on said measured two-dimensional position of said bright image spot on said positioning detector.