Terahertz spectroscopic identification of explosive and drug simulants concealed by various hiding techniques

Puc, Uroš; Abina, Andreja; Rutar, Melita; Zidanšek, Aleksander; Jeglic, A.; Valušis, Gintaras

doi:10.1364/ao.54.004495

Cited by 87 publications

(35 citation statements)

References 26 publications

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“…THz spectroscopy and imaging were actively used for this purpose during the past twenty years in the wide area of security applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. At the same time, this technique starts to be widely used for the non-destructive testing, for quality inspection of pharmaceuticals and food products as well as for medical applications [20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

High effective THz-TDS method for the detection and identification of substances in real conditions

et al. 2016

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Low efficiency of the standard THz-TDS method for the detection and identification of substances is demonstrated. For this purpose, we use a few examples. In the first example, we model the noisy THz signals transmitted through the amphetamine-type stimulant in real conditions. Namely, with a temperature 18° C, the relative humidity of about 50 % and the distance between the parabolic mirror and the object about of 3.5 meters. We show that the standard THz-TDS method reveals the spectral features of many neutral substances and explosives in the noisy THz signals from the illicit stimulant MA, at the same time this method is not able to detect the presence of this stimulant in the noisy signals. The second example is the detection and identification of plastids with inhomogeneous surface in reflection mode. We show that inhomogeneous surface distorts spectral characteristics of the reflected THz signal main pulse, which cannot be used for the detection and identification of the plastids by means of the THz TDS method. In the last example we show that even under laboratory conditions (at short distance from the receiver), THz TDS detects in the semiconductors the absorption frequencies, which belong to both hazardous and neutral substances. To overcome this disadvantage, we propose to use the time-dependent spectrum of the THz pulse, transmitted through or reflected from a substance. For quality assessment of the presence of the standard substance absorption frequency in the signal under analysis, we use time-dependent integral correlation criteria. The influence of aperture placed in front of the sample on spectral properties of silicon wafers with different resistivity is demonstrated as well.Keywords: reflected and transmitted THz pulse, noisy THz pulse, method of spectral dynamics analysis, integral correlation criteria, identification of explosives and drugs. *vatro@cs.msu.ru; phone 7 495 939-5255; fax 7 495 939-2597

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Section: Introductionmentioning

confidence: 99%

High effective THz-TDS method for the detection and identification of substances in real conditions

et al. 2016

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“…Next, we prepared three samples with various mean grain sizes of RDX particles (below 100, 200-250 and 300-350 μm) to study the influence of solubility and scattering. They are called PAX-41_100, PAX-41_200 and PAX-41_300, respectively (numbers [17][18][19]. The sample of IMX-104 (IMX-101) consisted of mixed powders of RDX and NTO (NQ and NTO) with a particle Both the internal structure of the cast disc (revealed from small broken-off pieces) and its surface were imaged using an SEM microscope.…”

Section: Sample Preparation and Characterizationmentioning

confidence: 99%

“…One of the driving forces behind the development of the terahertz technique (the spectral range from 0.1 to 10 THz) is the fact that many commonly used explosive materials (such as RDX, PETN, HMX, TNT and NQ) have unique spectral features in this range of radiation [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Moreover, non-polar dielectric materials (such as clothes, paper and plastics) are relatively transparent in the range up to about 3 THz [6,9], which raises hope of efficient identification of explosive materials remaining under cover or being inside packaging [6,12].…”

Section: Introductionmentioning

confidence: 99%

“…Experiments have been carried out in different temperatures [14]; also, solid-state density functional theory calculations have been performed [15]. Methods for identifying explosive materials by means of their spectra are constantly being developed [16][17][18][19]. RDX is the most widely investigated material due to the fact that it is a constituent of many commonly used plastic materials (such as C-4 and Semtex) and meltcastable materials (like Composition B).…”

Section: Introductionmentioning

confidence: 99%

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Transmission and Reflection Terahertz Spectroscopy of Insensitive Melt-Cast High-Explosive Materials

Pałka

Szala

2016

J Infrared Milli Terahz Waves

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Currently, artillery shells and grenades that are introduced into the market are based on melt-castable insensitive high explosives (IHEs), which do not explode while they run a risk of impact, heat or shrapnel. Particles of explosives (such as hexogen, nitroguanidine and nitrotriazolone) are suspended in different proportions in a matrix of 2.4-dinitroanisole. In this paper, we investigated samples of commonly used IHEs: PAX-41, IMX-104 and IMX-101, whose internal structures were determined by a scanning electron microscope. Terahertz time domain spectroscopy was applied in both transmission and reflection configurations. At first, the complex refraction indices of four pure constituents creating IHEs were determined and became the basis of further calculations. Next, the experimentally determined transmission and reflection spectra of IHEs and pure constituents were compared with theoretical considerations. The influence of the grain size of constituent material and scattering on the reflection spectra was analysed, and good agreement between the experimental and theoretical data was achieved.

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“…One area where tools of such remote identification are of great interest is security since potentially this provides means for in-field detection of limited-circulation substances in luggage and concealed under clothes [8][9][10][11][12][13][14][15][16][17]. The reasoning behind this is that many hazardous substances have characteristic spectral fingerprints in a THz frequency range [10,11] while common materials (with the exception of water) have significantly simpler spectral features in the region.…”

Section: Introductionmentioning

confidence: 99%

THz TDS of substance covered by disordered structure

2016

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Computer simulation of a few-cycle pulse interaction with a substance covered by disordered structure is performed in order to study the effects imposed on spectra of transmitted and reflected pulses by presence of the cover. The substance is described by semi-classic approach and the cover is described by classic electrodynamics equations for linear isotropic medium. The cover consists of a number of layers with different properties which is considered to be the cause of the distortions. The influence of relation between pulse wavelength and cover layer thickness is illustrated. Computer simulation results are compared with those of physical experiments conducted for paper and other common materials.

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Terahertz spectroscopic identification of explosive and drug simulants concealed by various hiding techniques

Cited by 87 publications

References 26 publications

High effective THz-TDS method for the detection and identification of substances in real conditions

High effective THz-TDS method for the detection and identification of substances in real conditions

Transmission and Reflection Terahertz Spectroscopy of Insensitive Melt-Cast High-Explosive Materials

THz TDS of substance covered by disordered structure

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