Comparison of terahertz technologies for detection and identification of explosives

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

THz Reflection Spectra of Different Materials, Including Explosives, Measured at a Distance up to 5 m

This work presents a terahertz system designed for the reflection spectroscopy of different materials located at a distance up to 5 m. The source of the radiation is a tunable solid-state optical parametric oscillator, which generates a narrow-band nanosecond pulses in the range of 0.7-2.5 THz. The signal is detected with relatively fast and having big sensitivity hot electron bolometer. The detailed description of each device and the functioning of the experimental setup are provided as well as the methodology of the measurement is explained. Investigations were performed in the 0.7-2.2 THz range in free space with relative humidity of about 40%. The experiment was divided into three series, each of which was carried out with different distance between the examined sample and the system - 1 m, 3 m, and 5 m. Obtained spectra of selected materials, including explosives, are similar to the results received from a purged time domain spectroscopy system. The observed small deviations are connected with fluctuations of the laser wavelength and the instability of the bolometer

Transmission Spectra of Materials in the Terahertz Range Measured by a Hot Electron Bolometer-Based System

This paper presents an optical system for transmission spectral measurements in the terahertz range. The source of radiation is a tunable solid-state laser, which generates a narrow-band nanosecond pulses in the range 0.67-2.68 THz and based on optical parametric oscillator phenomenon. The signal is detected with a fast and sensitive hot electron bolometer. Principle of generation and detection of pulses as well as methodology of measuring spectral characteristics are presented. We compared the results obtained with the free-space setup, which is based on the optical parametric oscillator and hot electron bolometer, with a purged time domain spectroscopy system in the range of 0.7-2.2 THz

«Terahertz properties of liquid crystals doped with ferroelectric BaTiO₃ nanoparticles prepared by the sol-gel process»

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Selected polymers on CW and pulsed THz investigations

AbstractThe paper gives the results of refractive indexes for three plastic materials: polyethylene, polymethyl methacrylate and polyvinyl chloride, which are measured and compared in two arrangements - a CW THz photomixer and a pulsed THz spectrometer.</jats:p

Selected nonapeptides in terahertz light

Eight synthetic histidine analogues of oxytocin and vasopressin are subject of investigations. The spectra of the peptides have been investigated in the terahertz band. The results are obtained in the terahertz time-domain spectroscopy arrangement