SRI International has designed and developed a fully automated frequency-agile CO2 DIAL (differential absorption lidar) system. The system sensor head consists of a single, frequency- agile, CO2, TEA laser; a 10-inch receiver telescope, a liquid-nitrogen-cooled HgCdTe detector; and a transmit energy monitor. The sensor head and its auxiliary equipment (including the data acquisition and processing system, laser power supply, and water cooler) are mounted in a Grumman-Olson 11-ft step van. The self-contained, mobile system can be used to detect and quantify many volatile organic compounds (VOCs) at parts per million sensitivities over open-path ranges to 5 km. Characterization and demonstration of the system is ongoing. However, data collected on benzene, toluene, xylene, methanol, ethyl acetate, acetic anhydride, and other VOCs will be described herein. The system could be used by industry and government agencies in stand-off monitoring to map VOC emission sources and transport patterns into surrounding communities. A single mobile system could be used for several locations to verify compliance with environmental regulations such as the 1990 Clean Air Act Amendments.
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