Terahertz technology to search for arms and narcotics

http://www.dlr.de/en/desktopdefault.aspx/tabid-6213/10205_read-31157/   9 June 2011  Security check using a millimetre-wave body scanner. Suspicious items detected on the person in the background are displayed on the screen on a schematic profile of the human body. Image: picture-alliance/dpa. Whether at airports or at mass events, Terahertz technology can enhance the effectiveness of security checks. DLR is developing innovative methods to detect arms and hazardous substances. All airplane passengers are familiar with the security checks at the entrance to the restricted area. So far, screening has largely been confined to metallic objects which metal detectors can identify. In addition, authorities and security companies rely on pat-down checks. Now, contact-free examination methods have become mature enough for everyday use. One of them, Terahertz (THz) technology, is even is capable of discovering non-metallic objects. Arms and substances like pharmaceuticals, narcotics, and explosives are often hidden on the human body or in letters. In the THz spectral range, such dangerous objects and substances can be tracked down particularly well. In the electromagnetic spectrum, the THz band is located between the millimetre-wave and the infrared range, which corresponds to frequencies between 300 GHz and 10 THz and wavelengths of between 1mm and 30µm. Thanks to the technological progress made in recent years, the THz technology is now ready to make its great leap from purely academic research to practical application. Shorter than millimetre waves Terahertz image (in colour) of a dummy weapon hidden under a T-shirt. The Terahertz image was superimposed with a visual, black-and-white image of the same scene. The dummy weapon was 18 m away from the THz scanner. Image: DLR. There are several reasons why this should be so. First, THz radiation is capable of penetrating clothing as well as many packaging materials. The fact that the wavelength of THz rays is shorter than that of millimetre waves permits building systems and scanners that are more compact and have a greater range. This opens up entirely new application potential, possibilities the stationary body scanners currently on trial using millimetre waves are not capable of. Another advantage that THz rays have over millimetre waves: in the THz range, many substances, including explosives and pharmaceuticals, have their own characteristic absorption and reflection signatures called fingerprint spectra by which they can be identified. Moreover, unlike X-rays, THz radiation has no ionizing effect, which, from what we know today, makes it safe to use on humans. At the Institute of Planetary Research in Berlin-Adlershof, DLR has for years been systematically investigating the advantages of using THz radiation in security applications.  Scientists aim to develop serviceable system demonstrators with a focus on THz scanners that are capable of detecting hidden objects from distances in excess of five metres. More than that: under favourable conditions, researchers were able to detect hidden objects from a distance of no less than 20 metres. Another research focus is on developing THz spectrometers to identify explosives. Yet another is to combine THz sensors with other detection methods. Cooperation with partners at home and abroad Terahertz image of a closed envelope containing the chip of an electronic musical greeting card and a small bag filled with sugar. Other electronic components and substances can be detected in a similar way. Image: DLR. In THz research, DLR cooperates with leading research institutions, industrial partners, and small and medium-sized enterprises at home and abroad. It manages or participates in security research projects of the Federal Ministry of Education and Research (BMBF), the European Commission, and other organisations. Thus, for example, the TeraSec project, one of the European Commission’s first security research projects, was coordinated by DLR. More than a dozen partners from five member countries participated in TeraSec, six from the industrial sector, seven universities, and three research institutions. Their shared objective is to improve THz technology as a means to maintain both security and mobility. Scientists from two of DLR’s main research areas, space and transport, are involved in this project, which at the same time forms part of DLR´s security research, a cross departmental programme under which defence- and security-related research and development activities are being planned and controlled.

Contact

Prof.Dr. Heinz-Wilhelm Hübers   German Aerospace Center Institute of Planetary Research, Experimental Planetary Physics Tel.: +49 30 67055-596 Fax: +49 30 67055-507