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Article
Publication date: 12 July 2011

Przemysław Łopato, Tomasz Chady and Ryszard Sikora

The purpose of this paper is to present capabilities of terahertz imaging technology in case of various composite materials and to propose a new defect detection algorithm.

Abstract

Purpose

The purpose of this paper is to present capabilities of terahertz imaging technology in case of various composite materials and to propose a new defect detection algorithm.

Design/methodology/approach

This paper first discusses an applicability of the terahertz technique in composite materials inspection. It then describes source of terahertz radiation (photoconductive antenna) and general structure of terahertz time domain imaging system. Next the terahertz imaging results of composite anticorrosion coating, glass‐ and carbon‐fiber‐reinforced laminates are presented. Then the signal processing and identification scheme based on time domain A‐scan signal equalization and C‐scan thresholding is presented. Data processed in this way are parameterized and defect identification database is prepared. The proposed procedure is verified using the exemplary inspection results of glass‐fiber laminate delamination. Finally, some comparison of terahertz time domain inspection with low energy digital radiography is presented.

Findings

This paper shows terahertz imaging as a well‐suited technique for composite structures inspection. The terahertz imaging results of composite anticorrosion coating, glass‐ and carbon‐fiber‐reinforced laminates are presented. An application of proposed signal processing algorithm enables accurate defects detection and effective data collection for identification database purpose.

Originality/value

The paper provides an insight into the potential of terahertz imaging of various composite structures. Proposed signal processing and defects detection scheme is applicable to wide range of composite structures.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 4 July 2016

Przemyslaw Lopato

– The purpose of this paper is to present a system for automatic recognition of defects detected in non-conductive polymer composites using pulsed terahertz imaging.

Abstract

Purpose

The purpose of this paper is to present a system for automatic recognition of defects detected in non-conductive polymer composites using pulsed terahertz imaging.

Design/methodology/approach

On the beginning, non-destructive evaluation of composites using electromagnetic waves in terahertz frequency is shortly introduced. Next automatic defects recognition (ADR) algorithm is proposed, focussing on new features calculation. Dimensionality of features space is reduced by using principal component analysis. Finally, results of basalt fiber reinforced composite materials inspection and identification using artificial neural networks is presented and discussed.

Findings

It is possible to develop ADR system for non-destructive evaluation of dielectric materials using pulsed terahertz technique. New set of features in time and frequency domains is proposed and verified.

Originality/value

ADR in non-destructive testing is utilized in case of digital radiography and ultrasonic testing. Terahertz inspection with pulsed excitation is reported as a source of many useful information about the internal structure of the dielectric material. Up to now ADR based on terahertz non-destructive evaluation systems was not utilized.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 May 2005

Reviews the latest management developments across the globe and pinpoints practical implications from cutting‐edge research and case studies.

Abstract

Purpose

Reviews the latest management developments across the globe and pinpoints practical implications from cutting‐edge research and case studies.

Design/methodology/approach

Scans the top 400 management publications in the world to identify the most topical issues and latest concepts. These are presented in an easy‐to‐digest briefing of no more than 1,500 words.

Findings

Major technology advances have long since enabled us to “see” beyond the limits of visible light. Yet, while X‐rays, ultraviolet light and near infrared radiation have all been exploited, one potentially important region of the electromagnetic spectrum – between infra red and microwaves – has remained relatively unexplored; terahertz radiation, or t‐rays.

Practical implications

Provides strategic insights and practical thinking that have influenced some of the world's leading organizations.

Originality/value

The briefing saves busy executives and researchers hours of reading time by selecting only the very best, most pertinent information and presenting it in a condensed and easy‐to digest format.

Details

Strategic Direction, vol. 21 no. 5
Type: Research Article
ISSN: 0258-0543

Keywords

Article
Publication date: 3 May 2013

Przemyslaw Lopato, Tomasz Chady, Ryszard Sikora, Stanislaw Gratkowski and Marcin Ziolkowski

The purpose of this paper is to describe the full‐wave modelling of pulsed terahertz systems utilized in non‐destructive testing.

Abstract

Purpose

The purpose of this paper is to describe the full‐wave modelling of pulsed terahertz systems utilized in non‐destructive testing.

Design/methodology/approach

At the outset, some basic information on the terahertz NDT are outlined and then, general remarks on its numerical modelling are presented. Frequency domain FEM and time domain FDTD analysis is carried out. Finally comparison of computed and measured signals is shown in order to prove numerical analysis correctness.

Findings

It is possible to model in a relatively simple way a terahertz system for nondestructive evaluation of dielectric materials. In contrast to other published work, the entire measuring setup is modelled, including photoconductive antenna with hemispherical lens, focusing lens and evaluated material with exemplary defect.

Originality/value

This paper gives a description of the terahertz non‐destructive testing system with comparison of simulated and measured results.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 8 January 2018

Robert Bogue

This paper aims to provide a technical insight into a selection of recent developments and applications involving terahertz sensing technology.

1038

Abstract

Purpose

This paper aims to provide a technical insight into a selection of recent developments and applications involving terahertz sensing technology.

Design/methodology/approach

Following an introduction, the first part of this paper considers a selection of research activities involving terahertz radiation sources and detectors. The second part seeks to illustrate how the technology is exerting a commercial impact and discusses a number of product developments and applications.

Findings

Terahertz sensing is a rapidly developing field and a strong body of research seeks to develop sources and detectors with enhanced features which often exploit novel materials, phenomena and technologies. Commercialisation is gathering pace, and a growing number of companies are producing terahertz sensing and imaging products which are finding a diversity of applications.

Originality/value

This provides details of recent research, product developments and applications involving terahertz sensing technology.

Details

Sensor Review, vol. 38 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 26 January 2021

Elakkiya A., Radha Sankararajan and Sreeja B.S.

The proposed metamaterial absorber (MMA) has the following advantages: first, the structure of the MMA consists of one planar metallic resonator, which presents a new…

Abstract

Purpose

The proposed metamaterial absorber (MMA) has the following advantages: first, the structure of the MMA consists of one planar metallic resonator, which presents a new design approach to obtain a multiband absorption response, rather than using multiple unit-cells in the one large unit cell or stacking different layers. Second, the simultaneous realization of triple-band and dual-band absorption (or bi-functional absorption) at five different frequencies can integrate the respective advantages of the triple functions of the triple-band MMA and double-band MMA, and therefore, the bi-functional MMA will find more application prospects than multiple-functional devices of triple-band and dual-band. Third, the authors simulated the three combinations of MMA here, which is indium tin oxide (ITO)-Polyimide-ITO, ITO-Teflon-ITO and ITO-polyethylene terephthalate (PET)-ITO for the same planar structure and achieve a high absorption rate. Finally, the proposed structure is polarization and angle independent in nature.

Design/methodology/approach

This absorption device consists of the top circular resonator, the middle insulating SiO2 medium layer and the bottom metallic copper ground plane placed on a substrate. The conductivity of the copper metal is s = 5.8 × 107 s/m. As the transmission of the MMA structure is zero, the substrate materials can be selected randomly. Totally four combinations of terahertz MMA are designed and simulated here which are ITO- SiO2 –ITO, ITO-Polyimide-ITO, ITO-Teflon-ITO and ITO- PET-ITO for the same planar structure.

Findings

Compared with previous MMAs, the proposed MMA has the following advantages: First, the structure of the MMA consists of one planar metallic resonator, which presents a new design approach to obtain a multiband absorption response, rather than using multiple unit-cells in the one large unit cell or stacking different layers. Second, the simultaneous realization of triple-band and dual-band absorption (or bi-functional absorption) at five different frequencies can integrate the respective advantages of the triple functions of the triple-band MMA and double-band MMA, and therefore, the bi-functional MMA will find more application prospects than multiple-functional devices of triple-band and dual-band. Third, the authors simulated the three combinations of MMA here, which is ITO-polyimide-ITO, ITO-Teflon-ITO and ITO- PET-ITO for the same planar structure and achieve a high absorption rate. Finally, the proposed structure is polarization and angle independent in nature.

Originality/value

First, the structure of the MMA consists of one planar metallic resonator, which presents a new design approach to obtain a multiband absorption response, rather than using multiple unit-cells in the one large unit cell or stacking different layers. Second, the simultaneous realization of triple-band and dual-band absorption (or bi-functional absorption) at five different frequencies can integrate the respective advantages of the triple functions of the triple-band MMA and double-band MMA, and therefore, the bi-functional MMA will find more application prospects than multiple-functional devices of triple-band and dual-band. Third, the authors simulated the three combinations of MMA here, which is ITO-polyimide-ITO, ITO-Teflon-ITO and ITO-PET-ITO for the same planar structure and achieve a high absorption rate. Finally, the proposed structure is polarization and angle independent in nature.

Details

Circuit World, vol. 48 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 June 2005

Robert Bogue

This paper describes the discovery of waveguides capable of transmitting electromagnetic radiation at terahertz (THz) frequencies. Until now this has not been possible…

Abstract

Purpose

This paper describes the discovery of waveguides capable of transmitting electromagnetic radiation at terahertz (THz) frequencies. Until now this has not been possible, despite extensive research.

Design/methodology/approach

The discovery was made by a research group at Rice University whilst working on apertureless, near‐field THz microscopy. By chance, the group found that bare metal wires are capable of transmitting THz radiation to and from remote samples with virtually no dispersion and little attenuation.

Findings

This discovery allows THz waves to be taken directly to and from the source and detector and eliminates the need for objects to be positioned directly in the THz beam. It also overcomes problems associated with shock and vibration. Subsequently, the group used this phenomenon to develop the world's first prototype THz‐frequency endoscope, which was used to examine a glass flask.

Originality/value

The availability of THz waveguides will allow many new applications to be realised. A major use is expected to be security, where systems could be used for checking passengers and baggage at airports, etc. for concealed weapons, drugs and explosives. Uses in product quality control and healthcare are also anticipated.

Details

Sensor Review, vol. 25 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 15 July 2020

Elakkiya A., Radha Sankararajan, Sreeja B.S. and Manikandan E.

A novel and simple six-band metamaterial absorber is proposed in the terahertz region, which is composed of an I-shaped absorber and circular ring with four gaps and a…

Abstract

Purpose

A novel and simple six-band metamaterial absorber is proposed in the terahertz region, which is composed of an I-shaped absorber and circular ring with four gaps and a continuous metal ground plane separated by only 0.125 mm polyimide dielectric substrate. Initially, I-shaped resonator gives three bands at 0.4, 0.468 and 0.4928 THz with the absorptivity of 99.3%, 97.9% and 99.1%, respectively. The purpose of this paper is to improve the number of bands, for which the authors added the circular ring with four gaps, so the simulated metamaterial absorber exhibited six absorption peaks at 0.3392, 0.3528, 0.3968, 0.4676, 0.4768 and 0.492 THz, with the absorption rate of 91.4%, 94.2%, 94.9%, 90.3%, 77.5% and 97.4%, respectively. The surface current distribution and angle independence are explained for all the six frequencies which are used to analyze the absorption mechanism clearly. Structure maximum uses the squares and circles, so it will make the fabrication easy. The multiband absorbers obtained here have potential applications in many engineering technology, thermal radiation, material detection and imaging and optoelectronic areas.

Design/methodology/approach

This paper presents the design of the six-band metamaterial absorber which is from the I-shaped resonator and circular ring with four gaps and the metallic ground plane separated by the 0.125 polyimide dielectric substrate. The absorber exhibited six absorption peaks at 0.3392, 0.3528, 0.3968, 0.4676, 0.4768 and 0.492 THz, with the absorption rate of 91.4%, 94.2%, 94.9%, 90.3%, 77.5% and 97.4%, respectively. From the fabrication point of view, the proposed six-band metamaterial absorber has a very simple geometrical structure, and it is very easy to be fabricated.

Findings

The authors present a new and simple design of six-band absorber based on an I-shaped absorber and circular ring with four gaps and a metallic ground plane separated by a polyimide layer having the thickness of 0.125 mm. Six different resonance absorption peaks are found at 0.3392, 0.3528, 0.3968, 0.4676 , 0.4768 and 0.492 THz. Surface current distribution and angle independence plot have been studied to understand the absorption behavior of the designed terahertz metamaterial absorber.

Originality/value

The multiband absorbers obtained here have potential applications in many engineering technology, thermal radiation, material detection, security, sensors, imaging and optoelectronic areas.

Details

Circuit World, vol. 46 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Content available
Article
Publication date: 25 January 2011

90

Abstract

Details

Sensor Review, vol. 31 no. 1
Type: Research Article
ISSN: 0260-2288

Article
Publication date: 1 October 2006

Christine Connolly

To review recent developments in machine vision hardware and techniques, as revealed in the Image Processing and Optical Technology Exhibition, 2006.

Abstract

Purpose

To review recent developments in machine vision hardware and techniques, as revealed in the Image Processing and Optical Technology Exhibition, 2006.

Design/methodology/approach

Different sections of the paper examine new cameras and their interfacing, smart cameras with DSP processors, a powerful framegrabber, high intensity light emitting diode (LED) lighting, and developments in teraherz sources and detection.

Findings

Smart cameras now exist with greater processing speed than a PC. A new generic programming interface aims to ease the incompatibilities of digital cameras. Water cooling has produced a very intense and long life LED light, and a novel goniophotometer has no moving parts. Rapid advances are occurring in the field of terahertz imaging.

Originality/value

Provides an update on machine vision technology for scientists and engineers generally, and a source of contact information for specialists to follow up where necessary.

Details

Sensor Review, vol. 26 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

1 – 10 of 119