Terahertz Systems for Security Applications
Hidden objects revealed – and identified
- Plastics, paper and cardboard are transparent in the THz range.
- Imaging with terahertz waves reveals hidden objects.
- Many explosives and illicit drugs show spectroscopic “fingerprints”.
- Recommended systems: TeraFlash pro, Imaging Extension, TeraFlash smart, TeraScan
Terahertz systems offer a unique combination of imaging and spectroscopic methods. Terahertz waves penetrate materials like plastics, paper and – to some extent – textiles. They can thus reveal the presence of objects e.g. concealed in parcels, and identify the material in question by spectroscopic techniques. Prospective applications include the detection of drugs or explosives in mail envelopes, or the identification of liquids in suspicious bottles.
Generally, both time-domain and frequency-domain systems have proven suitable for terahertz imaging. Continuous-wave systems – in particular in conjunction with a broadband Schottky receivers – offer inexpensive, yet flexible solutions for researchers who wish to explore the potential of “spectroscopic imaging”. On the other hand, pulsed systems additionally gain depth information and provide 3D-images of the internal structure of an object.
- Review paper: Naftaly, M., et al., Industrial applications of terahertz sensing: State of play, Sensors (2019)
- Publication: M. Yahyapour et al., Fastest thickness measurements with a terahertz time-domain system based on electronically controlled optical sampling; Appl. Sciences (2019)
- Publication: N. Vieweg et al., Terahertz-time domain spectrometer with 90 dB peak dynamic range; J Infrared Milli. Terahz. Waves 35:10 (2014)
- Scientific Paper: A. Roggenbuck et al., Coherent broadband continuous-wave terahertz spectroscopy on solid-state samples; New J. Phys. 12 (2010)