A new technique that uses far-infrared (terahertz) radiation to rapidly identify bulk or airborne materials inside sealed paper or plastic containers has been demonstrated by scientists at the National Institute of Standards and Technology (NIST) and SPARTA Inc., of Rosslyn, Va. The technology has several applications in homeland security such as detection of explosives in the mail.
The method involves directing a far-infrared light source at a sample in a closed container, detecting the light transmitted through the materials, and then analyzing the light that was absorbed by the sample.
The technique has proved useful in detecting aerosols (such as those that might contain anthrax spores), pharmaceutical powders, most gases, several explosives, and other common materials. Researchers plan to increase the sensitivity and speed of the technology with future experiments.