A trace chemical detector is described that combines external-cavity quantum cascade lasers and a mercury cadmium telluride camera to capture hyperspectral images of the diffuse reflectance from a target surface in the long-wave infrared. The system is able to generate individual hypercubes in <0.1 s. When raster scanning the laser beam over the target surface, areal coverage rates of >60 cm2 / s have been achieved. Results are presented for standoff distances ranging from 0.1 to 25 m. Hyperspectral images generated by the system are analyzed for spectral features that indicate the presence of trace surface contaminants. This approach has been found to be highly capable of detecting trace chemical residues on a wide variety of surfaces, and we present a collection of detection results to demonstrate the capabilities of this technology. Examples include the detection of 10 μg of saccharin powder on a wide range of substrates, 0.2 μg of an explosive residue on a computer keyboard, residual pharmaceuticals within a plastic baggie, and a contaminated fingerprint on cell phone case.
Laser-based, long-wave infrared (LWIR) hyperspectral imaging systems are being developed for the standoff detection of trace chemicals on surfaces. Results of testing this technology at the Indianapolis Motor Speedway during the Indy500 will be presented. Also, we will describe two prototype systems that are being developed to address two different applications. One prototype will be mounted on a pan/tilt pointing system and be capable of detection at standoff distances between 5 and 30 m. A second system is being designed to screen parcels while they are being transported on a conveyor belt.