Laser optical system

Claim 1

AN INFRARED OPTICAL SYSTEM ADAPTED FOR VIEWING AT A RELATIVELY LONG RANGE UNDER CONDITIONS OF EXTREMELY LOW AMBIENT ILLUMINATION COMPRISING MEANS FOR GENERATING A PULSED NARROW, PULSED BEAM OF INFRARED RADIATION DIRECTED TOWARD A SELECTED TARGET AREA LOCATED AT A RELATIVELY LONG DISTANCE THEREFROM, EACH PULSE OF RADIATION HAVING A DURATION IN THE RANGE OF 2 TO 12 MILLISECONDS AND AN ENERGY OUTPUT IN THE RANGE OF 50 TO 100 JOULES, MEANS HIGHLY SENSITIVE TO EXTREMELY LOW LEVELS OF ILLUMINATION IN THE INFRARED REGION FOR DETECTING INFRARED RADIATION BEING REFLECTED BY SAID TARGET AREA AND FOR INTENSIFYING AN OPTICAL IMAGE THEREOF, MEANS CONNECTED TO AN OUTPUT OF SAID DETECTING AND IMAGE INTENSIFYING MEANS FOR PRODUCING A TEMPORARY IMAGE OF SAID TARGET AREA UNDER AMBIENT ILLUMINATION CONDITIONS OF SUBSTANTIALLY TOTAL DARKNESS, AND MEANS IN OPTICAL COMMUNICATION WITH SAID TEMPORARY IMAGE PRODUCING MEANS FOR PHOTOGRAPHING THE TEMPORARY IMAGE OF SAID TARGET AREA TO THEREBY RECORD A PERMANENT IMAGE OF SAID TARGET AREA UNDER AMBIENT ILLUMINATION CONDITIONS OF SUBSTANTIALLY TOTAL DARKNESS BY AN INDIRECT PHOTOGRAPHIC METHOD HAVING APPROXIMATELY 40 TIMES THE SENSITIVITY OF DIRECT METHODS OF PHOTOGRAPHING SAID TARGET AREA UNDER SIMILAR ILLUMINATION CONDITIONS, AND MEANS FOR SYNCHRONIZING SAID DETECTING AND IMAGE INTENSIFYING MEANS AND PHOTOGRAPHING MEANS WITH SAID RADIATION GENERATING MEANS WHEREBY SAID DETECTING MEANS AND PHOTOGRAPHING MEANS ARE RESPONSIVE TO THE REFLECTED RADIATION DURING ONLY A PREDETERMINED INTERVAL OF TIME THEREBY PREVENTING UNDESIRED RADIATION OCCURRING AT INTERVALS OTHER THAN DURING THE OPERATION OF SAID INFRARED OPTICAL SYSTEM FROM DEGRADING THE OPTICAL IMAGE BEING PERMANENTLY RECORDED.