Abstract: This specification discloses a communication apparatus provided with light emitting means for generating transmission light modulated by an information signal, light receiving means for receiving modulated reception light, an optical member for reflecting one of the transmission light and the reception light and transmitting the other therethrough, a reflecting member for reflecting the transmission light emerging from the optical member to the transmission side and reflecting the reception light to the optical member, light splitting means for splitting part of the reception light obtained through the optical member, detecting means for detecting the positional state of the light obtained from the light splitting means, and driving means for rotatively driving the reflecting member about two axes in accordance with the positional state of the light detected by the detecting means.

Abstract: An optical space communication apparatus for propagating a beam of light through free space to thereby effect communication includes a transmitting device for transmitting a first optical signal converted into a beam of light, a expanse angle varying device for varying the angle of expanse of the beam of light into which the first optical signal has been converted, a level varying device for varying the output level of the first optical signal, a control device for controlling the expanse angle varying device and the level varying device, and a receiving device for receiving a second optical signal converted into a beam of light.