Remote measurement of HCI, CH(4), and N(2)O using a single-ended chemical-laser lidar system

The applicability of the high energy discretely tuned DF laser for remote measurement of HCl, CH(4), and N(2)O has been investigated. A single-ended or monostatic lidar system using radiation backscattered from topographical targets was tested. Selective absorption of the backscattered signal was used to infer concentration of gaseous species. Good agreement was obtained between the lidar measurements and the concentrations determined by in situ measurements in the remotely positioned sample chamber. The lowest measurable material concentration for each gas was inferred from random fluctuations in the measured concentration. Sensitivity of the existing system to HCl, CH(4), and N(2)O was found to be 0.05 ppm-km, 6.0 ppm-km, and 0.24 ppm-km, respectively. An N(2)O plume was also measured in the open atmosphere between the lidar system and a foliage target to demonstrate system capabilities under typical field conditions. Performance predictions indicate that total burden and range-resolved species concentration measurements are feasible to a range of 10 km or more with commercially available components.