Low-power ultraviolet lidar for standoff detection of BW agents

A compact ultraviolet lidar stand-off sensor was recently developed and field-tested for detection of bio warfare (BW) agent stimulant aerosols and interferents. It employed a low-power (~5mW), continuous-wave, 375nm semiconductor ultraviolet optical source (SUVOS) laser diode that was modulated at high-speed with a pseudo-random (PR) code to provide range-resolved lidar detection of both aerosol elastic scattering and fluorescence. The sensor incorporated a 150mm diameter receiver telescope and 3 photon-counting detection channels centered at 375nm, 440nm, and 550nm. Aerosol elastic and fluorescence lidar profiles were obtained by correlating the signal photon-counts with the PR code. Tests of the lidar were performed first with simulants released in the Large Aerosol Chamber at Edgewood Chemical and Biological Center, MD at a lidar range of only 7.5m. The second phase of testing was done at Dugway Proving Ground, UT. Here the lidar was continuously scanned (± 13°) in a horizontal plane to detect downwind simulant and interferent aerosol disseminations at ranges of several hundred meters. Preliminary analyses of these tests show that the lidar detected fluorescence from the BW simulants at ranges up to 100m, and elastic scattering from aerosols up to 350m.