Source: http://www.afmc.af.mil/news/story.asp?id=123044434AirForceMaterielCommand

    Air Force Office of Scientific Research-funded scientists at the University of Bath, England, are using radiation to detect dangerous materials.

    To detect the materials ¡ª biological agents, chemical explosives, imperfections, contamination and hidden compartments found in confined spaces ¡ª scientists combine terahertz radiation and metamaterials technology.

    Terahertz radiation interacts with substances such as light and other radiation types. The interaction occurs in ways different from naturally occurring materials known as metamaterial technology. Terahertz radiation and metamaterial technology work together to guide wavelengths into narrow spaces or holes where they can detect explosives as they absorb the radiation.

    Research previously was unable to prove the usefulness of this kind of radiation because the components to conduct experiments ¡ª such as lenses, polarizers, beamsplitters, and mirrors ¡ª were not readily available.

    According to Dr. Gernot Pomrenke, the AFOSR program manager who is overseeing the project, promising application of the interaction lies in the fields of environmental, biological, and security sensing.

    ¡°A successful experimental demonstration of guiding and focusing of terahertz radiation will have a major impact on all scientific and technological areas where radiation in the far-infrared region is employed,¡± said Mr. Pomrenke, who manages the high density optical memory and the optoelectronics (components and information processing) portfolios for AFOSR.

    Terahertz radiation becomes visible and identifiable because it is transmitted through many substances such as cardboard, clothing, plastic, and wood. It can potentially be used to search the contents of containers or for hidden devices under clothing.

    ¡°Metal wires can be used to guide radiation around them but, unfortunately, the waves extend a distance into the surrounding areas, increasing loss,¡± said Dr. Stefan Maier, principal investigator on the project at the University of Bath. ¡°We found that by regularly structuring the wires with ring-shaped grooves, we can confine the waves much more strongly. The challenge now is to make the grooves on the wires deep.¡±

    Deep grooves, he explained, help the radiation ¡¯stick¡¯ closely to the wire in large concentrations, but the technique isn¡¯t easy to do. He said the team plans to use laser machining or direct milling to achieve this goal.