Laser Remote Sensing: FY07 Summary Report

Standoff detection and characterization of chemical plumes using Frequency Modulated Differential Absorption Lidar (FM-DIAL) is a promising technique for the detection of nuclear proliferation activities. For the last several years Pacific Northwest National Laboratory (PNNL) has been developing an FM-DIAL based remote sensing system as part of PNNL's Infrared Sensors project within NA-22's Enabling Technologies portfolio. In FY06 the remote sensing effort became a stand-alone project within the Plutonium Production portfolio with the primary goal of transitioning technology from the laboratory to the user community. Current systems remotely detect trace chemicals in the atmosphere over path lengths of hundreds of meters for monostatic operation (without a retro-reflector target) and up to ten kilometers for bistatic operation (with a retro-reflector target). The FM-DIAL sensor is sensitive and highly selective for chemicals with narrow-band absorption features on the order of 1-2 cm-1; as a result, the FM-DIAL sensors are best suited to simple di-atomic or tri-atomic molecules and other molecules with unusually narrow absorption features. A broadband sensor is currently being developed. It is designed to detect chemicals with spectral features on the order of several 10s of wavenumbers wide. This will expand the applicability of this technology to the detection of more complicated molecules. Our efforts in FY07 focused on the detection of chemicals associated with the PUREX process. The highest value performance measure for FY07, namely the demonstration of the Broadband Laser Spectrometer (BLS) during chemical release experiments, was successfully achieved in June, July and August of this year. Significant advancements have been made with each of the other tasks as well. A short-wave infrared version of the miniature FM-DIAL (FM-Mini) instrument was successfully demonstrated during field tests in June. During FY07 another version of the FM-Mini was built using long-wave infrared components. This instrument was deployed for field tests in July and August. The modeling task continued to study the impact of speckle on the FM-DIAL system as well as make further advancements in the sophistication of the numerical simulations.