Arrangement for transmitting a light beam carrying an information signal through the atmosphere

摘要

In an optical atmospheric link system for transmitting a light beam carrying an information signal between a transmitter and a receiver which is located apart from the transmitter, the transmitter includes a light source for generating the first light beam modulated with the information signal, a first optical system for transmitting the light beam toward the receiver, a second optical system for turning at least a portion of the light beam, and a third optical system for observing the light beam turned by the second optical system and the receiver. Also, the receiver includes a first detector for receiving the first light beam transmitted from the transmitter through the first optical system, detecting a relative position of the first light beam received and the receiver and for generating a position error signal, a second light source for generating a second light beam modulated with the position error signal, and a second optical system for transmitting the second light beam generated by the second light source toward the transmitter, wherein the transmitter further includes a second detector for receiving the second light beam transmitted from the receiver through the second optical system and demodulating the second light beam to obtain the position error signal, and a position control circuit for controlling a position of the transmitter according to the position error signal obtained by the second detector so that the light beam is directed toward the receiver.