LARGE COHERENT ARRAYS FOR LASER RADARS

OUR "SELF-COHERING" METHODS PERMIT INCREASING THE RECEIVE APERTURE OF A LASER RADAR FAR BEYOND WHAT CONVENTIONAL OPTICAL DESIGNS ALLOW, THUS ACHIEVING UNPRECEDENTED RESOLUTION AND RANGE CAPABILITIES. A COHERENT APERTURE IS FORMED FROM A NUMBER OF MUCH SMALLER SUBAPERTURES WITHOUT REQUIRING STRICT MECHANICAL RIGIDITY. THE OTHERWISE USELESS DISTORTED APERTURE IS PHASE CORRECTED WITH NO NEED FOR A "PHASE-UP" SOURCE OF OPPORTUNITY BY PROCESSING THE RERADIATED FIELD FROM A FAIRLY GENERAL SCENE IN A NUMBER OF INNOVATIVE WAYS. DIFFRACTION LIMITED PERFORMANCE IS ACHIEVED. LARGE APERTURE LIDARS FIND NUMEROUS APPLICATIONS WHERE MECHANICAL VIBRATIONS EXIST (E.G., AN OPTICAL "SMART SKIN" DISTRIBUTED OVER THE SURFACE OF AN AIRCRAFT FOR DETECTING LOW RCS GROUND VEHICLES, OR FOR THEATER MISSILE DEFENSE). OUR METHODS COMPENSATE FOR THE DYNAMIC DISTORTION DUE TO VIBRATIONS AND PHASE ERRORS DUE TO THE ATMOSPHERE. MOREOVER, OPTICAL SUBAPERTURES CAN BE CONNECTED TO THE DETECTORS USING LIGHT-WEIGHT, INEXPENSIVE, FLEXIBLE OPTICAL FIBERS WITH NO PHASE TRIMMING. RESULTING PHASE ERRORS ARE CORRECTED AS WELL.