Explosives Detection by Terahertz Spectroscopy—A Bridge Too Far?

TLDR

Terahertz spectroscopy has been investigated for concealed explosives detection since spectroscopic signatures in common explosives were first identified almost 10 years ago. The paper investigates the feasibility of developing a deployable person‑borne IED detection system using terahertz spectroscopy. It examines the physical challenges, such as signal attenuation and interference, that impede practical deployment. The study concludes that terahertz spectroscopy is unlikely to be practical for safe, through‑barrier explosive detection because weak, broad spectral features are masked by atmospheric water vapor, barrier attenuation, and scattering, though lower‑frequency terahertz imaging may offer a more promising security application.

Abstract

Terahertz spectroscopy has been investigated as a technique for concealed explosives detection since spectroscopic signatures in common explosives were first identified almost 10 years ago. This paper explores the progress towards practical development of the technology and the physical basis of the challenges involved in creating a deployable person-borne IED detection system. We conclude that, despite the theoretical potential of terahertz to provide a safe, through-barrier spectroscopic detection technique, this is unlikely to be possible in practice. The relatively weak and broad explosives features tend to be masked by the combined effects of atmospheric water vapor absorption, barrier attenuation and scattering from both clothing and the target explosives. Imaging at the lower end of the terahertz frequency range, although not offering the same specificity, is a more promising technique for security applications.