OPTICAL INFORMATION TRANSMITTING DEVICE AND METHOD

摘要

PROBLEM TO BE SOLVED: To provide an optical narrow cast system which can solve a problem where the power density is increased at a focal point that is set when the laser beams are condensed by a lens, etc., by modulating a laser beam based on the multiplex signal that is obtained by multiplexing plural information signals and then diffusing the laser beam to transmit these diffused beams as the signal beams. SOLUTION: A multiplexing part 24 of a transmitter 20A multiplexes the modulated signals S23A to S23C in terms of frequency and outputs them to a laser drive amplifier 25 as a multiplex signal S24. The amplifier 25 generates a laser drive current S25 from the signal S24 and transmits it to a laser diode 26. The diode 26 operates in response to the current S25 and transmits the signal beams S26 as the laser beams. A lens 27 sends the beams S26 to a surface wavefront converter 28 as parallel beams. Then two diffusion plates 29 of the converter 28 diffuse the passing beams S26 and transmit them as the signals S20A which have no characteristic of the coherent light.