Microcavity Device for Measuring Direction of a Laser Beacon

An optoelectronic device based on interferometry in a resonant microcavity has been proposed for use in measuring the direction of arrival of a circularly polarized beam of light from a beacon laser. In comparison with prior optoelectronic direction sensors, the proposed device would be simple, compact, and lightweight, in that it would contain no moving parts and no imaging optics and could be fabricated from semiconductor crystals. Moreover, it should be possible to integrate readout electronic circuits directly onto the device; these circuits would perform all needed intermediate signal processing to generate electrical output indicative of the angle of incidence of the laser beam on the device. In one potential application, the beacon would be located at one end of a free-space optical-communication link and would be used as a target for aiming a transmitting telescope located at the other end of the link. In another potential application, the beacon could be used similarly as a target for measuring angles precisely in land surveying.