Detection and identification of explosives hidden under barrier materials: what are the THz-technology challenges?

Rheenen, Arthur D. van; Haakestad, Magnus W.

doi:10.1117/12.886108

Cited by 9 publications

(13 citation statements)

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“…A great deal of research has been performed on the spectral signatures of explosives and related materials through THz TDS, including the conventional molecular explosives RDX, HMX, PETN, and simulant molecules [23][24][25][26][27][28]. Likewise, the spectral signatures of explosive mixtures and plastic compositions have been studied [26][27][28][29][30][31][32][33]. Additionally, spectral signatures of homemade explosives and related materials have been analyzed [34][35][36].…”

Section: Terahertz Spectroscopy and Imagingmentioning

confidence: 99%

“…), surface roughness of the samples, and water vapor or humidity present in the air [30,37]. Many researchers have addressed these challenges through developing methods to separate spectral fingerprints of explosives from barrier materials [30,31,[38][39][40], and signal-processing algorithms to compensate for water-vapor absorption [32].…”

Section: Terahertz Spectroscopy and Imagingmentioning

confidence: 99%

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Advances in explosives analysis—part II: photon and neutron methods

et al. 2015

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The number and capability of explosives detection and analysis methods have increased dramatically since publication of the Analytical and Bioanalytical Chemistry special issue devoted to Explosives Analysis [Moore DS, Goodpaster JV, Anal Bioanal Chem 395:245-246, 2009]. Here we review and critically evaluate the latest (the past five years) important advances in explosives detection, with details of the improvements over previous methods, and suggest possible avenues towards further advances in, e.g., stand-off distance, detection limit, selectivity, and penetration through camouflage or packaging. The review consists of two parts. Part I discussed methods based on animals, chemicals (including colorimetry, molecularly imprinted polymers, electrochemistry, and immunochemistry), ions (both ion-mobility spectrometry and mass spectrometry), and mechanical devices. This part, Part II, will review methods based on photons, from very energetic photons including X-rays and gamma rays down to the terahertz range, and neutrons.

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Section: Terahertz Spectroscopy and Imagingmentioning

confidence: 99%

Section: Terahertz Spectroscopy and Imagingmentioning

confidence: 99%

Advances in explosives analysis—part II: photon and neutron methods

et al. 2015

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“…The THz time-domain spectroscopy (THz TDS) is a non-destructive tool that is very popular nowadays for both basic research and the security screening and for industrial applications also. Is well known that the THz pulsed TDS is traditionally used for the detection and identification of explosive and illicit drug [1][2][3][4][5][6][7][8][9][10]. Moreover, it is currently considered to be a new powerful tool for application in the chemical sciences and molecular structure investigations [11][12][13][14], nondestructive inspections [15][16][17][18], thickness measurements [19,20], art investigations [21,22], pharmaceutical and biomedical applications [23][24][25][26], and food quality control [27][28][29].…”

Section: Literature Review and Introductionmentioning

confidence: 99%

Spurious Absorption Frequency Appearance Due to Frequency Conversion Processes in Pulsed THz TDS Problems

Trofimov

Wang

Qiu

et al. 2020

Sensors

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The appearance of the spurious absorption frequencies caused by the frequency conversion process at the broadband THz pulse propagation in a medium is theoretically and experimentally discussed. The spurious absorption frequencies appear due to both the frequency doubling and generation of waves with sum or difference frequency. Such generation might occur because of the nonlinear response of a medium or its non-instantaneous response. This phenomenon is confirmed by the results of a few physical experiments provided with the THz CW signals and broadband THz pulses that are transmitted through the ordinary or dangerous substances. A high correlation between the time-dependent spectral intensities for the basic frequency and generated frequencies is demonstrated while using the computer simulation results. This feature of the frequency conversion might be used for the detection and identification of a substance.

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“…Obviously, all these issues have been realized before and there is a vast body of literature [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] on identifying substances by comparing their spectra. Spectral features have been measured in numerous wavelength bands corresponding to the energies of the transitions of interest.…”

Section: Introductionmentioning

confidence: 99%

Robust identification of concealed dangerous substances using THz imaging spectroscopy

2015

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False alarm rates must be kept sufficiently low if a method to detect and identify objects or substances is to be implemented in real life applications. This is also true when trying to detect and identify dangerous substances such as explosives and drugs that are concealed in packaging materials. THz technology may be suited to detect these substances, especially when imaging and spectroscopy are combined. To achieve reasonable throughput, the detection and identification process must be automated and this implies reliance on algorithms to perform this task, rather than human beings. The identification part of the algorithm must compare spectral features of the unknown substance with those in a library of features and determining the distance, in some sense, between these features. If the distance is less than some defined threshold a match is declared. In this paper we consider two types of spectral characteristic that are derived from measured time-domain signals measured in the THz regime: the absorbance and its derivative. Also, we consider two schemes to measure the distance between the unknown and library characteristics: Spectral Angle Mapping (SAM) and Principal Component Analysis (PCA). Finally, the effect of windowing of the measured time-domain signal on the performance of the algorithms is studied, by varying the Blackman-Harris (B-H) window width. Algorithm performance is quantified by studying the receiver-operating characteristics (ROC). For the data considered in this study we conclude that the best performance is obtained when the derivative of the absorbance is used in combination with a narrow B-H window and SAM. SAM is a more straight-forward method and requires no large training data sets and tweaking.

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Detection and identification of explosives hidden under barrier materials: what are the THz-technology challenges?

Cited by 9 publications

References 0 publications

Advances in explosives analysis—part II: photon and neutron methods

Advances in explosives analysis—part II: photon and neutron methods

Spurious Absorption Frequency Appearance Due to Frequency Conversion Processes in Pulsed THz TDS Problems

Robust identification of concealed dangerous substances using THz imaging spectroscopy

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