Automatic Acquisition and Tracking System for Laser Communication

A laser communication system, which has an automatic acquisition and tracking capability without the aid of any other communication link, has been constructed and experimented. It consists of two terminals that can transmit one TV signal and error signals for tracking each other. The heart of this system is a combination of a laser, a position sensor, an angle detector, and an optical deflector that can send back a laser beam parallel to an incident beam as if it were a retroreflector. The availability of this system was proved from a transmission experiment at the distance of 500 m. The maximum propagation distance of this system is estimated to be 1 km if a 200-mm diameter receiving aperture is used, even though there are spot dancing and beam spreads.