Free space optical transmission system.

摘要

A spatial optical transmission apparatus includes: a light signal transmitting device for generating a signal beam which is modulated in accordance with a signal to be transmitted and is intensity-modulated with a lower frequency compared with a signal transmission speed; and a light signal demodulating device for receiving the signal beam from the light signal transmitting device by a detector, adjusting the direction of a locally oscillated beam based on the received signal beam so as to have a predetermined relationship with the direction of the signal beam so that intensity-modulated components in an output signal from the detector falls within a predetermined range of intensity, thereby aligning the wavefront of the signal beam with the wavefront of the locally oscillated beam, and extracting signal components which correspond to the transmitted signal from signal components modulated in accordance with the transmitted signal in the signal beam.