SIGNALLING SYSTEM

摘要

An optical signalling system is provided comprising first and second signalling devices. The first signalling device comprises a retro-reflector and the second signalling device comprises a light source for transmitting light towards the retro-reflector. The second signalling device also includes means for controllably steering the optical signal towards the first signalling device; means for sensing the signal strength of the reflected signal; and means for controlling the steering means in dependence upon the sensed signal strength. The steering means may steer the beam using reflective, refractive or diffractive techniques.