Self-Alignment FSOC System With Miniaturized Structure for Small Mobile Platform

This paper presents a miniaturized equipment used in tracking and pointing, and provides a method for free space optical communication among small platform. This scheme uses simple scan mirror and receiver with single photo detector to achieve tracking function. Signal beacon is controlled to rotate around target receiver. Transmitter constantly adjusts emitting direction to track receiver according to received signal intensity, which is send back by reverse laser link. The prototype system is successfully established and its transmitting part consisted by directly modulated laser diode, mechanical collimation lens, and scan mirror is also proved. The receiving end is mainly composed of large area photo detector and short-focal lens. Field-programmable gate array chips set in both ends are used to implement tracking algorithm. This system can track target at speed of 40 mm/s within 2 m distance in an angle range of ±30°. For further application, the system has great potential for miniaturization because of elimination of motors, beacons and cameras in its scheme.