Patent attributes
A device and method detect a moving, relatively thin beam of laser light, and distinguishing between illumination of photodetectors by the beam, and illumination of the photodetectors by an omnidirectional pulse of light. A plurality of photodetector arrays are arranged in a generally vertical row, with each array having a generally vertical row of photodetector elements. Weighting circuits associated with the arrays provide first and second reference signals for each array related to the elements illuminated in the array. The ratio of sum of the reference signals to the difference between the largest and smallest of the reference signals is determined and interpreted as indicating illumination by a relatively thin beam of laser light when the ratio is less than a predetermined level, and as indicating illumination by an omnidirectional pulse of light when the ratio is greater than the predetermined level.
