Patent ID: 6433330
Filing Date: 2002-08-13
Classification: G01J,G01S

Abstract:
A light detection system for detecting laser beams where high levels of light from an extraneous source may be present at one area in the system's field-of-view, the light detection system comprising means to focus an image of the field-of-view onto a surface of a photodetector, an optical limiter being located between the means to focus and the photodetector, the optical limiter having means to limit transmission of said high levels of light received from the extraneous source at a particular area where the high levels are directed onto the optical limiter by the means to focus, the optical limiter remaining transmissive to light received from areas in the field-of-view outside of said particular area and allowing any laser beam received from the field-of-view outside of the particular area to be focussed onto the photodetector, said photodetector comprising a position sensing photodetector from which the position of any laser beam focussed onto the photodetector can be determined and an angle-of-arrival of such a laser beam can be determined from said position, and said optical limiter comprising a liquid crystal display (LCD) and said system further including means to determine the location on the LCD of an area onto which the high levels of light are directed by the means to focus, the system further including means to activate the LCD to place the LCD in an opaque mode at the area where said high levels of light are directed.