Abstract: An apparatus detects the presence and location of at least one object in a field. The apparatus comprises a rotating arm which spins around the field, a position sensor for detecting the angular displacement of the rotating arm relative to a fixed point, and a processor. The rotating arm includes a transmitter and an opposing receiver array mounted thereon and fixed relative to each other. The receiver array includes a plurality of receivers located horizontally coplanar with each other. The receivers are concentrated towards one side of the receiver array which is aligned with a center region of the dartboard. The transmitter outputs a detection beam that emanates from a single point, such as a divergent beam. The detection beam overlaps the field and is simultaneously received at all times by the plurality of receivers of the receiver array. The receivers detect changes which occur in the field as a result of an object being in the field, manifested by shadows on the field.

Abstract: A system for transmitting optical power from a first location to a second location. The system includes a first light source at the first location which generates a first light beam. A power converter detects the first light beam at the second location. A first control circuit coupled to the power converter operates a second light source at the second location to generate a return safety light beam after detection of the first light beam. A photodetector detects the return safety light beam at the first location. A second control circuit is coupled between the photodetector and the first light source. The second control circuit detects the presence of the return safety light beam and operates the first light source to generate the first light beam at a first power level prior to detecting the return safety light beam and at a second power level, higher than the first power level, after detecting the return safety light beam.