We present results on the comparison of different THz technologies for the detection and identification of a variety of explosives from our laboratory tests that were carried out in the framework of NATO SET-193 THz technology for stand-off detection of explosives: from laboratory spectroscopy to detection in the field under the same controlled conditions. Several laser-pumped pulsed broadband THz time-domain spectroscopy (TDS) systems as well as one electronic frequency-modulated continuous wave (FMCW) device recorded THz spectra in transmission and/or reflection. © 2014 SPIE

Concerning several attacks using letter bombs within Europe in the last couple of years and the highly rising number of new drugs, there is a need for new kinds of detection devices for explosives and drugs. We present a postscanner on basis of Terahertz (THz) spectroscopy using novel chemometric methods for the evaluation of detected THz fingerprints

One of the most prominent applications of terahertz time-domain spectroscopy is the spectral investigation of materials covered by visibly opaque objects. Therefore, terahertz waves are well suited to inspect the content of mail. We report on our work on mail inspection in this spectral range including machine design, optical layouts, data analysis, and implementations.

Terahertz (THz) spectroscopy is a powerful technique for identification of dangerous materials like drugs and explosives, especially when hidden under optically opaque concealments. Multiple-reflections within such sample systems lead to additional spectral features which could be misinterpreted as artificial material absorption bands. We show that combinations of different chemometric tools help reducing such misinterpretations. However, an angle-depending detection scheme leads to a much more powerful artifact suppression. We received experimental data which are in good agreement with our numerical predictions. Hence, the overall false alarm rate of our pattern-recognition algorithm is significantly reduced

Letter bombs are an increasing problem for public authorities, companies and public persons. Nowadays every big company uses in his headquarters inspection system to check the incoming correspondence. Generally x-ray systems are used to inspect complete baskets or bags of letters. This concept which works very fine in big company with a large postal center is not usable for small companies or private persons. For an office environment with a small number of letters x-ray systems are too expensive and oversized. X-ray systems visualize the wires and electric circuits inside the envelope. If a letter contains no metallic components but hazard materials or drugs, the dangerous content is invisible for the most low-cost x-ray systems. Millimeter wave imagining systems offer the potential to close this gap