Conceptual design of an acquisition, processing, and control system for a semi-autonomous, airborne, differential absorption lidar system

The Air Force Research Laboratory (AFRL) Laser Remote Optical Sensing (LROS) program has developed the Laser Airborne Remote Sensing (LARS) system for chemical detection using the differential absorption lidar (DIAL) technique. Airborne tests during the last year resulted in chemical detection at a slant range of 30 km. As the next step in the development process, concepts for a compact, semi-autonomous DIAL system are being considered. This paper describes the conceptual design and external interfaces of the acquisition, processing, and control system computers required to operate a semi-autonomous DIAL system. The conceptual design of the VME-based real-time computer system uses three CPUs: (1) a data acquisition and control CPU which synchronizes experiment timing and pulsed CO 2 laser operation while controlling lidar subsystem components such as pointing and tracking, wavelength sequencing, and optical alignment; (2) a data reduction CPU which serves as the semi-autonomous controller and performs real-time data reduction; and (3) a data analysis CPU which performs chemometric analysis including chemical identification and concentration. The triple-CPU and multi-layered software decouple time-critical and non-critical tasks allowing great flexibility in flight-time display and processing.