Patent attributes
An improved laser light beam receiver rejects unwanted pulses of optical energy, such as strobe lights or other flashes of light, that can occur on a jobsite. The receiver analyzes a light beam reception by using a photosensitive light beam detector arrangement and a separate photoelectric detector serving as an interference signal detector. This additional detector is not easily able to detect the light beams needed in normal operation. On the other hand, the additional detector does detect mostly all interfering light flashes—caused by flash lamps and other similar devices—whose threshold limit is either at the same level or below that of the light beam detector arrangement. An evaluating circuit such as a microcontroller correlates the time of reception of the light beam detector arrangement and the interference signal detector in order to discard the result if the times of reception correspond to a major extent.
