| 摘要 |
A laser communication system with improved reliability and exceptionally low bit error rake. The proposed laser communication system completely eliminates the effects of turbulence and provides free space performance. These objectives are achieved by transmitting a laser beam to a receiver so that the beam waist is located entirely within the aperture of the receiver where the aperture size exceeds the effective spot size of the beam including effects of diffraction, atmospheric turbulence, and beam pointing error. In a preferred embodiment an imaging tracker at the transmitter and a laser beacon with a diverging beam at the receiver permits the transmitter to point a focusing beam accurately enough to assure that the entire beam is captured in the receiver aperture. In another embodiment a laser beam is transmitted from a first location to a modulatable retro-reflector at a second location. The beam transmitted from the first location is directed to within the aperture of the retro-reflector. This beam may be sampled at the second location for communications from the first location to the second location. The retro-reflector is modulated for transmission of information from the second location to the first location. In a preferred embodiment the same antenna is used for transmission and for reception at the first location except the portion used for reception is at least twice as large as the portion used for transmission. |
