Acquisition and tracking system for optical radar

Claim 1

In a target acquisition and tracking system having a laser source for transmitting a laser beam, a modulator for modulating said transmitted laser beam at a predetermined frequency, and a beam steerer for scanning said modulated beam in search of a target, the improvement comprising: a target adapted to reflect said laser beam received thereon in a retrodirection, a telescope means having optic means associated therewith for directing Said transmitted laser beam from said beam steerer along the mechanical axis of said telescope means, said beam steerer adapted to direct said laser beam over a predetermined acquisition field in search of said target, said telescope means having optics for receiving said reflected laser beam from said target, a first image dissector associated with said telescope means, said telescope means having additional optic means adapted to direct said reflected laser beam toward the imaging section of said first image dissector, said first image dissector having a total field of view corresponding to said acquisition field of view, and an instantaneous field of view of about the size of the transmitted laser beam, a control system having an acquisition means for generating a first control signal for causing said first image dissector to raster scan its instantaneous field of view over its total field of view in search of the received reflected laser beam, and a second control signal to cause said beam steerer to direct said transmitted laser beam in a raster scan of said acquisition field of view in search for said target, both signals being slaved together so the total field of view of the first image dissector and said acquisition field of view are scanned coaxially in a corresponding manner, said first image dissector producing a tracking signal when the received reflected laser beam is detected within the total field of view, said control system having a tracking control means responsive to said tracking signal of said image dissector for causing said first image dissector to stop raster scanning and to start scanning its instantaneous field of view in a cross-scan pattern, said control system generating error signals representing the offset of the received reflected laser beam, and thus the target, from the center of said cross-scan pattern of said first image dissector, said control means being responsive to said error signals so as to cause said first image dissector to center said cross-scan pattern on said reflected laser beam regardless where it is in said total field of view, and said control means being responsive to said error signals to also cause said beam steerer to center said transmitted laser beam on said target.