Wednesday, 23 November 2011

AN EXPLORATION OF THE UTILITIES OF TERAHERTZ WAVES FOR THE NDE OF COMPOSITES

AN EXPLORATION OF THE UTILITIES OF TERAHERTZ WAVES FOR THE NDE OF COMPOSITES

AIP Conf. Proc. -- June 23, 2011 -- Volume 1335, pp. 533-540
REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Volume 30A; Volume 30B; doi:10.1063/1.3591897


ABSTRACT
Issue Date: 23 June 2011

David K. HsuKwang-Hee ImChien-Ping Chiou, and Daniel J. Barnard
Center for Nondestructive Evaluation, Iowa State University, Ames, Iowa 50011


We report an investigation of terahertz waves for the nondestructive evaluation of composite materials and structures. The modalities of the terahertz radiation used were time domain spectroscopy (TDS) and continuous wave (CW). The composite materials and structures investigated include both non-conducting polymeric composites and carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse can detect a crack hidden behind a larger crack. This was demonstrated in thick GFRP laminates containing double saw slots. In carbon composites the penetration of terahertz waves is quite limited and the detection of flaws is strongly affected by the angle between the electric field vector of the terahertz waves and the intervening fiber directions. The structures tested in this study include both solid laminates and honeycomb sandwiches. The defects and anomalies investigated by terahertz waves were foreign material inclusions, simulated disbond and delamination, mechanical impact damage, heat damage, and water or hydraulic fluid ingression. The effectiveness and limitations of terahertz radiation for the NDE of composites are discussed. ©2011 American Institute of Physics


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Friday, 18 November 2011

Explosives characterization in terahertz range (Proceedings Paper)

Author(s): I. Maestroju├ín; I. Palacios; D. Etayo; J. C. Iriarte; J. Teniente; I. Ederra; R. Gonzalo
Date: 13 October 2011

Paper Abstract

A Thz spectral characterization of the behaviour of different explosives is presented in this paper. This characterization will be done in the frequency range from 20 GHz to 4 THz using a Teraview Spectra 3000. This system has a capacity of measuring from 20 GHz to 4 THz fed by a laser source. With the Teraview Spectra 3000 equipment will be possible to calculate the refractive index, the absorbance and other important parameters of the explosive samples. With this study it will be possible to characterize some of the most common used explosives, i.e., gun explosive, gunpowder mine, pent, TNT, RDX, etc, and it will allow to determine their electromagnetic peculiarities in order to design a future imaging system that allow detecting them in security and defense sectors.

Millimetre Wave and Terahertz Sensors and Technology IV, Keith A. Krapels;Neil A. SalmonEddie Jacobs, Editors, 81880N


DOI: 10.1117/12.898152

Thursday, 3 November 2011

Terahertz Time-Domain Spectroscopy of Solid Samples: Principles, Applications, and Challenges


... Different ranges are specified in both the peer-reviewed literature (2–4) and documentation from instrument vendors (55. TeraView. “Terahertz radiation”. Available at: http://teraview.co.uk/terahertz/...


DOI:
10.1080/05704928.2011.614305
Ryan M. Smitha & Mark A. Arnolda
pages 636-679
Available online: 07 Oct 2011

Abstract

Advances in ultrafast lasers and semiconductor technologies have facilitated access to the terahertz (THz) frequency range for spectroscopic and imaging purposes. THz time-domain spectroscopy (TDS) is commonly used to acquire spectral data having high signal-to-noise ratios (SNRs) over a broad range of THz frequencies. THz-TDS instrumentation is commercially available, thereby enabling novel applications of THz time-domain (TD) imaging and spectroscopy in a myriad of applications. This review gives a general description of the instrumentation available for collecting THz-TD data and focuses on measurements of solid samples. Measurement geometries useful for collecting THz-TD data from solid samples are reviewed and a summary is presented of the major applications to the analysis of solid samples related to security issues, as well as samples originating from the pharmaceutical industry, dental sciences, biological samples, and polymer materials. Emphasis is also given to analytical applications in a discussion of the analytical challenges met in quantification of solid analytes by THz-TDS methods.

To read more about this review:


for more information about  the Spectra 3000 spectrometer click here
(http://www.teraview.com/products/terahertz-pulsed-spectra-3000/index.html)