AN ACRONYM FOR LASER IMAGING DETECTION AND RANGING, LIDAR ILLUMINATES THE ENVIRONMENT WITHIN ITS FIELD OF VIEW AND CREATES A 3D IMAGE OF THE SURROUNDINGS. THE THIRD DIMENSION (DISTANCE TO A POINT) IS DETERMINED BY MEASURING THE TIME IT TAKES FOR THE REFLECTED LIGHT TO REACH BACK TO THE DEVICE. LIDAR IS A VERY HIGH-RESOLUTION VERSION OF RADAR.
THERE ARE TWO MAIN TYPES OF LIDAR: FLASH AND SCANNING. IN FLASH LIDAR, THE ENTIRE SEEN IS ILLUMINATED WITH A SINGLE PULSE OF LIGHT AND THE REFLECTED LIGHT IS IMAGED (PIXELATED) USING A DETECTOR ARRAY. IN SCANNED LIDAR, A NARROW LASER BEAM DEFINES THE PIXEL SIZE THAT IS SCANNED ACROSS THE SCENE TO BUILD THE 3D IMAGE.
SIMULTANEOUS ILLUMINATION OF THE ENTIRE SCENE ALLOWS FOR FAST FRAME UPDATES WITH FLASH LIDAR. HOWEVER, POWER REQUIREMENTS LIMIT RANGE, AND DETECTOR ARRAY SIZES LIMIT RESOLUTION. SCANNING ALLOWS FOR MUCH LONGER EFFECTIVE RANGE BUT CURRENT SCANNING TECHNOLOGIES ARE SLOW AND FRAME REFRESH RATES ARE LIMITED TO WELL BELOW REAL TIME IMAGING.
AN ELECTRONIC BEAM SCANNING TECHNIQUE USING AN ARRAY OF LASER EMITTERS WITH PRECISION PHASE CONTROL CAN ACHIEVE THE REQUISITE SCANNING SPEEDS TO ENABLE HIGH SPEED IMAGING WHILE MAINTAINING LONG OPERATING RANGE. RESOLUTION CAN ALSO BE ENHANCED THROUGH SYNTHETIC APERTURE ENHANCEMENT. SATISFACTORY IMPLEMENTATION OF PHASED ARRAY LIDAR DEPENDS ON COMPONENT TECHNOLOGIES AND SYSTEM ARCHITECTURES YET TO BE DEMONSTRATED IN COMMERCIAL SYSTEMS.