Patent ID: 7343099

Claim:
A free-space optical (FSO) laser communication system automatically stabilizing variations in the detected intensity of laser beam carrier signals, caused by atmospheric turbulence along signal reception channels supported within said FSO laser communication system, said FSO laser communication system comprising: at least first and second communication terminals in optical communication by way of a broad-band FSO laser beam communication link supporting signal transmission and reception channels; wherein each said communication terminal has a transmitter module and a receiver module; and wherein each said receiver module includes a receiving aperture for receiving a FSO laser beam carrier signal transmitted from said transmitter module of another one of said communication terminals; a fast steering mirror (FSM) for steering said FSO laser beam carrier signal along an optical pathway having downstream direction; a beam splitter, disposed downstream from said FSM, for splitting said FSO laser beam carrier signal into a first signal component and a second signal component; a receiving optical fiber, disposed at the end of said optical pathway, for receiving the second component of said FSO laser beam carrier signal after transmission along said optical pathway; a single-cell signal detector in optical communication with said receiving optical fiber, for detecting the intensity of said second component of said FSO laser beam carrier signal and generating an electrical signal corresponding thereto; a multi-segment signal detector, disposed downstream from said beam splitter, for detecting the intensity of said first signal component of said FSO laser beam carrier signal, and generating electrical signals corresponding thereto; a processor for automatically analyzing signals generated from said multi-segment signal detector, controlling said FSM, and automatically tracking or following a maximum intensity laser beam speckle in said FSO laser beam carrier signal, and moving low intensity laser beam speckles appearing in said FSO laser beam carrier signal away from said receiving optical fiber, and thereby achieving a first level of optical signal intensity stabilization at said single-cell signal detector in said receiver module; a spatial modulator for spatially modulating said second component of said FSO laser beam carrier signal; said processor further analyzing electrical signals produced by said single-cell signal detector, controlling said spatial modulator, and spatially modulating said second component of said FSO laser beam carrier signal so as to lock a maximum intensity speckle appearing in the received second component of said FSO laser beam carrier signal, onto said receiving optical fiber, and thereby achieving a second level of optical signal intensity stabilization at said single-cell signal detector in said receiver module.