PARTIALLY COHERENT (WIDEBAND) INFRARED LIDAR SYSTEM FOR SPACE BASED AEROSOL BACKSCATTER AND CLOUD HEIGHT MEASUREMENTS

BECAUSE OF LIMITATIONS IN DETECTOR TECHNOLOGY IT IS NOT CURRENTLY PRACTICAL TO OPERATE AN INCOHERENT SPACE LIDAR IN THE EYESAFE REGION FOR AEROSOL BACKSCATTER MEASUREMENT. THIS PROPOSED EFFORT COMBINES THE SIMPLICITY OF INCOHERENT LIDARS WITH THE EXTREME SENSITIVITY OF COHERENT DETECTION TO OBTAIN SENSITIVE PERFORMANCE IN THE EYESAFE INFRARED REGION. THIS EFFORT WILL DETERMINE THE FEASIBILITY, PERFORMANCE, AND DESIGN PARAMETERS OF A "SIMPLIFIED", PARTIALLY COHERENT (WIDEBAND), INFRARED LASER RADAR SYSTEM FOR AEROSOL BACKSCATTER AND CLOUD HEIGHT MEASUREMENTS FROM A SPACE PLATFORM OPERATING IN THE EYESAFE REGION. THE PARTIALLY COHERENT LIDAR SYSTEM WILL RETAIN THE HETERODYNE DETECTION PROCESS, AND THEREFORE THE LOCAL OSCILLATOR, OF A FULLY COHERENT LIDAR SYSTEM, BUT WILL HAVE RELAXED SPECIFICATIONS IN THE AREAS OF TRANSMITTED PULSE FREQUENCY STABILITY, LOCAL OSCILLATOR FREQUENCY STABILITY, TRANSMITTED PULSE NARROW BANDWIDTH, RECEIVER NARROW BANDWIDTH, MECHANICAL AND OPTICAL TOLERANCES, AND DATA PROCESSING COMPLEXITY. IT WILL THEREFORE APPROACH THE SIMPLICITY OF AN INCOHERENT LIDAR SYSTEM BUT WILL BE MANY ORDERS OF MAGNITUDE MORE SENSITIVE IN THE EYESAFE, COVERT, INFRARED REGION ABOVE 1.4 MICRONS. IT IS EXPECTED THAT PARTIALLY COHERENT LIDAR SYSTEMS WILL BE IDEALLY SUITED TO THE PRESENT TECHNOLOGY IN SHORT-PULSE (WIDEBAND) INJECTIONSEEDED SOLID-STATE LASERS.