An Effective Method for Substance Detection Using the Broad Spectrum THz Signal: A "Terahertz Nose"

Trofimov, Vyacheslav A.; Varentsova, Svetlana A.

doi:10.3390/s150612103

Cited by 36 publications

(67 citation statements)

References 39 publications

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“…In [30], [31] the integral criteria of probability assessment for the detection and identification of substance were proposed. In [32]- [36], [41] the spectral properties of THz pulses measured at long distances of about 3.5 meters were investigated by means of modified integral criteria.…”

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%

See 1 more Smart Citation

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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“…[1][2][3] Several efforts have been made for advancing the THz devices, [4][5][6] among which the THz absorber is believed to be a crucial component in developing THz detectors and sensors.…”

Section: Introductionmentioning

confidence: 99%

Electrically tunable terahertz dual-band metamaterial absorber based on a liquid crystal

Yin

Xia

et al. 2018

RSC Adv.

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In this paper, a liquid crystal (LC) based tunable metamaterial absorber with dual-band absorption is presented. The proposed absorber is analysed both numerically and experimentally. The analysis shows that the two absorption peaks, originating from the new resonant structure, are experimentally detected at 269.8 GHz and 301.4 GHz when no bias voltage is applied to the LC layer. In order to understand the absorption mechanisms, simulation results for the surface current and power loss distributions are presented. Since liquid crystals are used as the dielectric layer to realize the electrically tunable absorber, a frequency tunability of 2.45% and 3.65% for the two absorption peaks is experimentally demonstrated by changing the bias voltage of the LC layer from 0 V to 12 V. Furthermore, the absorber is polarization independent and a high absorption for a wide range of oblique incidence is achieved. The designed absorber provides a way forward for the realization of tunable metamaterial devices that can be applied in multi-band detection and imaging.

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An Effective Method for Substance Detection Using the Broad Spectrum THz Signal: A "Terahertz Nose"

Cited by 36 publications

References 39 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

Electrically tunable terahertz dual-band metamaterial absorber based on a liquid crystal

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