STANDOFF SENSING AND IMAGING OF EXPLOSIVE RELATED CHEMICAL AND BIO-CHEMICAL MATERIALS USING THz-TDS

2007 ◽  
Vol 17 (02) ◽  
pp. 239-249 ◽  
Author(s):  
Hua Zhong ◽  
Albert Redo-Sanchez ◽  
Xi-Cheng Zhang
Keyword(s):  
Remote Sensing ◽  
Glutamic Acid ◽  
Time Domain ◽  
Large Scale ◽  
Imaging System ◽  
Terahertz Time Domain Spectroscopy ◽  
Multiple Absorption ◽  
Thz Absorption ◽  
Absorption Features ◽  
Chemical Materials

We report the sensing and imaging of explosive related chemical and bio-chemical materials by using terahertz time domain spectroscopy (THz-TDS) at standoff distance. The 0.82 THz absorption peak of RDX is observed at a distance up to 30 m away from the emitter and receiver. Multiple absorption features of RDX, 2,4-DNT and Glutamic Acid are identified by using a large scale 2-D imaging system. These results support the feasibility of using THz-TDS technique in remote sensing and detection of chemical materials.

scholarly journals Transformation and dehydration kinetics of methylene blue hydrates detected by terahertz time-domain spectroscopy

RSC Advances ◽  
2017 ◽  
Vol 7 (66) ◽  
pp. 41667-41674 ◽  
Author(s):  
Shihan Yan ◽  
Hua Zhang ◽  
Zhongbo Yang ◽  
Mingjie Tang ◽  
Mingkun Zhang ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Time Domain ◽  
Terahertz Spectroscopy ◽  
Dehydration Kinetics ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Thz Absorption ◽  
Kinetics Of ◽  
Absorption Features ◽  
Crystalline Hydrates

Three methylene blue crystalline hydrates were identified by terahertz spectroscopy according to their different THz absorption features.

SIGNATURE AND SIGNAL GENERATION ASPECTS OF EXPLOSIVE DETECTION USING TERAHERTZ TIME-DOMAIN SPECTROSCOPY

2008 ◽  
Vol 18 (02) ◽  
pp. 295-306 ◽  
Author(s):  
ROBERT OSIANDER ◽  
MICHAEL J. FITCH ◽  
MEGAN LEAHY-HOPPA ◽  
YAMAC DIKMELIK ◽  
JAMES B. SPICER
Keyword(s):  
Time Domain ◽  
Explosive Detection ◽  
Reflection Spectra ◽  
Terahertz Time Domain Spectroscopy ◽  
Reflection And Transmission ◽  
Time Domain Spectroscopy ◽  
Grain Sizes ◽  
Full Analysis ◽  
Characteristic Features ◽  
Absorption Features

In the last few years, a number of researchers including our collaboration have assembled databases of terahertz (THz) time-domain spectroscopy (TDS) absorption spectra from bulk explosives. While this was a necessary and important step in demonstrating the feasibility of THz TDS for explosives detection, the goal of our research is to demonstrate selectivity of THz spectra from the clutter of background spectra coming from the substrate such as soil or sand. We have investigated THz TDS reflection spectra from sand with different grain sizes as well as from metallic powders in order to distinguish between the signals reflected from the rough surfaces compared to distributed reflections at finite depths in the granular material. With marker materials such as tartaric acid, which have absorption features in the 1-2 THz range, we have investigated the reflection spectra of granular substrates with marker chemicals, and compared this to reflection and transmission spectra of solid materials prepared in polyethylene sample pellets. In principle, the same experiments can then be performed using TNT, RDX, HMX and PETN, which all have characteristic features in the 0.5-8 THz frequency range. Absolute molecular absorption coefficients can be measured as well, and we include here preliminary values for RDX. A full analysis will be reported elsewhere.

Characteristic fingerprint spectrum of neurotransmitter norepinephrine with broadband terahertz time-domain spectroscopy

The Analyst ◽  
2019 ◽  
Vol 144 (8) ◽  
pp. 2504-2510 ◽  
Author(s):  
Zhongjie Zhu ◽  
Chao Cheng ◽  
Chao Chang ◽  
Guanhua Ren ◽  
Jianbing Zhang ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Time Domain ◽  
Vibrational Modes ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Thz Absorption ◽  
Broadband Terahertz

A broadband THz absorption spectrum of NE corresponds to specific vibrational modes.

Structurally Sensitive Changes in Absorption THz Spectra of Corticosteroids

2010 ◽  
Vol 5 (4) ◽  
pp. 162-167
Author(s):  
Irina N. Smirnova ◽  
Elena V. Fedulova ◽  
Maxim M. Nazarov ◽  
Оlga P. Cherkasova
Keyword(s):  
Steroid Hormones ◽  
Absorption Spectra ◽  
Time Domain ◽  
Spectral Response ◽  
Frequency Range ◽  
Terahertz Time Domain Spectroscopy ◽  
Characteristic Lines ◽  
Pure Substances ◽  
Thz Absorption ◽  
The Given

The series of steroid hormones, such as progesterone, 17α-hydroxyprogesterone, cortisol and other was measured by terahertz time-domain spectroscopy (THz TDS). It was obtained that THz absorption spectra of steroid hormones have characteristic lines of absorption in the frequency range 0.1-3.0 THz. We investigate the relation between the position of side functional groups and THz spectral response. Besides pellets of polycrystalline pure substances, steroids solution in methanol was analyzed. The given method can be applied for express diagnostics of different classes of steroid

scholarly journals Terahertz Time-domain Spectroscopy as a Novel Tool for Crystallographic Analysis in Cellulose: Cellulose I to Cellulose Ii, Tracing the Structural Changes Under Chemical Treatment

2021 ◽  
Author(s):  
Han Wang ◽  
Hiroki Kataoka ◽  
Satoru Tsuchikawa ◽  
Tetsuya Inagaki
Keyword(s):  
Absorption Coefficient ◽  
Time Domain ◽  
Structural Changes ◽  
Crystalline Lattice ◽  
Thz Radiation ◽  
Cellulose Ii ◽  
Cellulose I ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Thz Absorption

Abstract Terahertz time-domain spectroscopy (THz-TDS) has expanded possibilities in cellulose crystallography research, as THz radiation detects most intermolecular vibrations and responds to the phonons of crystalline lattices. In this study, we traced the transformation of the cellulose crystalline lattice from cellulose I to cellulose II by THz-TDS and X-ray powder diffraction. Cellulose II was obtained by treating cellulose I with NaOH of different concentrations (0 wt%–20 wt%, at 2 wt% intervals). The THz absorption coefficient spectra of cellulose II showed three characteristic peaks (at 1.32 THz, 1.76 THz, and 2.77 THz). The THz absorption coefficient spectra of cellulose II treated with 20-wt% NaOH and cellulose I without NaOH treatment were fitted by a seventh-order Fourier series. Thus, the THz absorption coefficient spectra of samples treated with NaOH of other concentrations could be considered a combination of these two fitted profiles of cellulose I and cellulose II, multiplied by different coefficients. Furthermore, the coefficients could reflect the relative contents of cellulose I and cellulose II in the samples.

scholarly journals Detection of Firmiana danxiaensis Canopies by a Customized Imaging System Mounted on an UAV Platform

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Chun Liu ◽  
Mengchi Ai ◽  
Zhuo Chen ◽  
Yuan Zhou ◽  
Hangbin Wu
Keyword(s):  
Remote Sensing ◽  
Plant Species ◽  
Local Governments ◽  
Large Scale ◽  
Imaging System ◽  
Hierarchical Classification ◽  
Support Vector ◽  
Svm Classifier ◽  
Surface Model ◽  
Rare And Endangered

The objective of this study was to test the effectiveness of mapping the canopies of Firmiana danxiaensis (FD), a rare and endangered plant species in China, from remotely sensed images acquired by a customized imaging system mounted on an unmanned aerial vehicle (UAV). The work was conducted in an experiment site (approximately 10 km2) at the foot of Danxia Mountain in Guangdong Province, China. The study was conducted as an experimental task for a to-be-launched large-scale FD surveying on Danxia Mountain (about 200 km2 in area) by remote sensing on UAV platforms. First, field-based spectra were collected through hand-held hyperspectral spectroradiometer and then analyzed to help design a classification schema which was capable of differentiating the targeted plant species in the study site. Second, remote-sensed images for the experiment site were acquired and calibrated through a variety of preprocessing steps. Orthoimages and a digital surface model (DSM) were generated as input data from the calibrated UAV images. The spectra and geometry features were used to segment the preprocessed UAV imagery into homogeneous patches. Lastly, a hierarchical classification, combined with a support vector machine (SVM), was proposed to identify FD canopies from the segmented patches. The effectiveness of the classification was evaluated by on-site GPS recordings. The result illustrated that the proposed hierarchical classification schema with a SVM classifier on the remote sensing imagery collected by the imaging system on UAV provided a promising method for mapping of the spatial distribution of the FD canopies, which serves as a replacement for field surveys in the attempt to realize a wide-scale plant survey by the local governments.

scholarly journals Quality Mapping of Offset Lithographic Printed Antenna Substrates and Electrodes by Millimeter-Wave Imaging

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 674
Author(s):  
Jiao Zhang ◽  
Jianhua Tang ◽  
Wenfeng Sun ◽  
Yan Zhang ◽  
Xinke Wang ◽  
...  
Keyword(s):  
Flexible Electronics ◽  
Time Scale ◽  
High Speed ◽  
Large Scale ◽  
Imaging System ◽  
Inspection Time ◽  
Large Area ◽  
Terahertz Time Domain Spectroscopy ◽  
Antenna Performance ◽  
Wave Imaging

Offset lithographic printed flexible antenna substrate boards and electrodes have attracted much attention recently due to the boost of flexible electronics. Unmanned quality inspection of these printed substrate boards and electrodes demands high-speed, large-scale and nondestructive methods, which is highly desired for manufacturing industries. The work here demonstrates two kinds of millimeter (mm)-wave imaging technologies for the quality (surface uniformity and functionality parameters) inspection of printed silver substrates and electrodes on paper and thin polyethylene film, respectively. One technology is a mm-wave line scanner system and the other is a terahertz-time domain spectroscopy-based charge-coupled device (CCD) imaging system. The former shows the ability of detecting transmitted mm-wave amplitude signals only; its detection is fast in a second time scale and the system shows great potential for the inspection of large-area printed surface uniformity. The latter technology achieves high spatial resolution images of up to hundreds of micrometers at the cost of increased inspection time, in a time scale of tens of seconds. With the exception of absorption rate information, the latter technology offers additional phase information, which can be used to work out 2D permittivity distribution. Moreover, its uniformity is vital for the antenna performance. Additionally, the results demonstrate that compression rolling treatment significantly improves the uniformity of printed silver surfaces and enhances the substrate’s permittivity values.

scholarly journals Terahertz spectroscopy and imaging for gastric cancer diagnosis

2020 ◽  
Author(s):  
Faustino Wahaia ◽  
Irmantas Kašalynas ◽  
Linas Minkevičius ◽  
Catia Carvalho Silva ◽  
Andrzej Urbanowicz ◽  
...  
Keyword(s):  
Time Domain ◽  
Terahertz Spectroscopy ◽  
Human Cancer ◽  
Terahertz Waves ◽  
Terahertz Time Domain Spectroscopy ◽  
Tissue Samples ◽  
Time Domain Spectroscopy ◽  
Affected Tissue ◽  
Gastrointestinal Tissue ◽  
Thz Absorption

Terahertz waves are sensitive to differences in biological tissue hydration, we present promising results regarding the feasibility of applying this with terahertz time-domain spectroscopy and imaging for early detection of cancer through the characterisation of human gastrointestinal tissue with cancer-affected regions. To do that, healthy (normal) and carcinoma-affected gastric tissue samples at different stages were measured using transmission terahertz time-domain spectroscopy in the frequency range of 0.15–2.00 THz. Absorption coefficients and refractive index spectra of both normal and carcinoma-affected tissue were extracted and analysed. The results confirm that the techniques may be powerful tools to perform qualitative, early diagnosis of human cancer.

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