Orthogonal Spectroscopic Technologies for the Detection of Hazardous Substances

Reliable, high-sensitivity detection and identification of hazardous substances at stand-off distances is beyond the reach current commercial solutions, such as laser induced breakdown spectroscopy. To improve the possibility of detection and lower false alarm rates, spectroscopic techniques orthogonal to conventional LIBS systems are required. We propose to combine femtosecond LIBS with a radical new air-based THz generation and detection technique to create an orthogonal spectroscopic system with unparalleled capabilities to detect and identify hazardous materials in field conditions. Nonlinear optical mixing in ambient air using a portable Ti:sapphire laser generates unprecedented intense and ultrabroad bandwidth THz pulses, exceeding the performance of current solid state materials. Heterodyne detection of pulsed THz waves by using the ambient air has also been demonstrated, and holds the potential to be the most sensitive detection method yet. This revolutionary technique can be applied anywhere there is air, even at distances considered impossible using conventional methods. The proposed project will integrate a commercial femtosecond LIBS with a THz-ABCD system, and prove the feasibility of using the two techniques together to improve detection reliability. A prototype with stand-off capability will be demonstrated in Phase II to detect explosive compounds in an site survey security context.