Identification of concealed materials, including explosives, by terahertz reflection spectroscopy

We report on a method for extracting the characteristic features of covered materials, including hexogen, in the range from 0.5 to 1.8 THz. This time-domain spectroscopy-based technique takes into account only part of the signal reflected from a covered sample and analyzes it by using the Fourier transform. The obtained power spectrum has distinctive peaks that correspond to peaks measured in the transmission configuration and can be used for further identification of the materials. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduc- tion of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.OE.53.3.031202) spectral dynamics analysis method for identification of explosives in the reflection regime. In this article, we propose a new signal processing method to reveal characteristic THz fingerprints of materials covered with semitransparent layers such as a sheet of polyethylene or paper in the range of about 0.5 to 1.8 THz. The method takes into account the only part of the signal reflected from the covered sample that is then analyzed in the frequency domain with the Fourier transform. The obtained spectrum has very distinctive peaks that correspond to the main peaks measured in the transmission configuration, and this obtained spectrum is what in turn makes reliable identifica- tion possible.