MODEL FOR PORT SCATTER FROM LASERS

SCATTER FROM GROUND-BASED LASER PORTS (WEAPONS, COMMUNICATION SYSTEMS, RANGE FINDERS) CAN BE LARGE ENOUGH THAT THE LASER LOCATION MAY BE DETERMINED BY DETECTORS POSITIONED WELL AWAY FROM THE BEAM. PORT SCATTER CAN BE REDUCED, BUT NOT ELIMINATED, THROUGH THE USE OF BAFFLES TO LIMIT DIRECT VIEWING OF THE LASER OPTICS. THIS DOCUMENT PROPOSES DEVELOPING A METHOD TO PREDICT THE SCATTER SIGNAL FROM LASER PORTS GIVEN THE DESIGN OF THE OUTPUT OPTICS AND BAFFLES. THE METHOD INVOLVES COMBINING SCATTER DATA FROM KNOWN TYPES OF COMPONENTS (WINDOW, MIRRORS, LENSES, BAFFLES) WITH A RAY TRACING COMPUTER PROGRAM THAT WILL FOLLOW SCATTER PROPAGATION THROUGH AN OPTICAL SYSTEM. LIGHT THAT IS SCATTERED THREE OR MORE TIMES IS IGNORED. THE OBSERVER IS ASSUMED TO BE IN THE DIFFRACTION FAR FIELD AND THE DETECTOR APERTURE LARGE ENOUGH SO THAT INTERFERENCE EFFECTS CAN BE IGNORED. THE OBJECT OF PHASE I IS TO DEMONSTRATE FEASIBILITY BY CORRECTLY PREDICTING THE PORT SCATTER FROM A SIMPLE HE-NE LASER, BAFFLE COMBINATION.