A method for determining relative movement between an optical navigation device and a navigation terrain includes generating two overlapping coherent optical beams, and generating a pattern of interference fringes between the two overlapping optical beams. The method further includes illuminating a surface...http://www.google.de/patents/US20050073693?utm_source=gb-gplus-sharePatent US20050073693 - System and method for optical navigation using a projected fringe technique
