Tuesday, 30 April 2013

Position at TeraView - Software Development Specialist

TeraView is developing ways to exploit terahertz (THz) radiation in many ground-breaking applications. We are currently developing a number of products that require highly-skilled, enthusiastic and energetic people to work in this evolving company.

We are seeking a Software Development Specialist to join our team; an individual who is able to meet the existing operational needs of the company, as well as planning for the future needs of the company as we grow.

You will have 2 years or more industry experience as a development engineer in scientific or engineering application environments. You will have worked within a formalised Quality System framework, with experience of scientific instrumentation. You must be able to demonstrate a track record of instrumentation or scientific software architecture design. You will be a self-starter with a positive attitude and a proven ability to work in small multi-disciplinary teams.

Role and Responsibilities:

Reporting to the Technical Development Team Leader, your responsibilities will include:
  • Design and development of software in support of instrumentation related to our terahertz systems, either individually or as part of a wider team
  • Hand-on work in prototyping and implementation of proposed solutions
  • Product design and related processes within a formal Quality Management System

Key Skills:  The successful applicant will have:

  • Extensive knowledge in at least one object-oriented development platform (C#, C++, Python or comparable)
  • A proven track record in the design of multi-threaded hardware/instrumentation control applications, graphical user-interface and desktop application design
  • The flexibility to develop across multiple languages / platforms
  • A scientific or engineering background
  • Experience of product design and related processes within a formal Quality Management System
  • Good interpersonal skills and attention to detail

Experience and Education:

  • Computer Science or Engineering degree 
  • Design and development of scientific measurement equipment, for example spectrometers or imaging systems
  • 2 years minimum industrial experience in scientific software or instrumentation
  • The ability to work alone and on own initiative
  • Ability to work in a team
  • Flexible approach to work
  • Experience of using boost and STL
  • 3D & 2D scientific visualisation
  • Robotics control or cybernetics
  • Signal processing, statistics and other data analysis methods
  • Knowledge of Matlab or other numerical analysis packages
  • SQL / Relational-database usage

If you think you have the skills and qualities we need, please send your CV, with a covering letter, outlining your current role and remuneration to:

Paddy O’Kelly
Chief Operating Officer
TeraView Limited
Platinum Building
St John’s Innovation Park
Cambridge CB4 0DS
e-mail: recruitment@teraview.com

No agencies, please.

TeraView offers an excellent salary and benefits package, along with the opportunity for highly-motivated staff to work together and shape the development of products in one of the newest and most exciting areas of technology. We are an equal opportunities employer and pride ourselves on our diverse workforce. For further information and background on the company, please visit our website on: www.teraview.com

Monday, 29 April 2013

THz periodic surfaces to enhance spectroscopic measurements

Proceeding from the International Conference on Electromagnetics in Advanced Applications (ICEAA), 2012 | 2-7 Sept. 2012

Authors: Woon-Gi Yeo1, Sanphuang, V.2; Nahar, N.K.1; Volakis, J.L.3
  1. Dept. of Electr. & Comput. Eng., +The Ohio State University, Columbus, OH, USA
  2. Fac. of Eng. & Technol., Asian Univ., Chon Buri, Thailand 
  3. Radiat. Lab., Michigan Univ., Ann Arbor, MI, USA 


We present a multi-layered frequency selective surfaces (FSS) exhibiting low losses for broad band spectroscopic measurements in THz frequencies. The intent is to replace existing samples holders (e. g. z-cut crystal quartz) with transparent metamaterial layers and increase measurement sensitivity. To enable multiband and broadband responses, a multilayered FSS is proposed, and thus suppress losses in a given range of THz bands.

More details at: http://dx.doi.org/10.1109/ICEAA.2012.6328766

Friday, 26 April 2013

Hardness and density distributions of pharmaceutical tablets measured by terahertz pulsed imaging

Journal of Pharmaceutical Sciences
22 Apr 2013; +Wiley Textbooks
DOI: 10.1002/jps.23560

Authors: Robert K. May1,4, Ke Su1, Lianghao Han2, Shuncong Zhong3, James A. Elliott2, Lynn F. Gladden1, Mike Evans4, Yaochun Shen3, J. Axel Zeitler1
1. Department of Chemical Engineering and Biotechnology,+Cambridge University Press Education, Cambridge CB2 3RA, UK
2. Department of Materials Science and Metallurgy, +Cambridge University Press Education, Cambridge CB2 3QZ, UK
3. Department of Electrical Engineering and Electronics, +University of Liverpool, Liverpool L69 3GJ, UK
4. +TeraView Ltd., St John’s Innovation Park, Cambridge, CB4 0WS, UK


We present terahertz pulsed imaging (TPI) as a novel tool to quantify the hardness and surface density distribution of pharmaceutical tablets. Good agreement between the surface refractive index (SRI) measured by TPI and the crushing force measured from diametral compression tests was found using a set of tablets that were compacted at various compression forces. We also found a strong correlation between TPI results and tablet bulk density, and how these relate to tablet hardness. Numerical simulations of tablet surface density distribution by finite element analysis exhibit excellent agreement with the TPI measured SRI maps. These results show that TPI has an advantage over traditional diametral compression and is more suitable for nondestructive hardness and density distribution monitoring and control of pharmaceutical manufacturing processes. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci

...Terahertz pulsed imaging reflection measurements of sample tablets were acquired using a TPI Imaga 2000 (TeraView Ltd., Cambridge, UK). A detailed description of the measurement technique was presented earlier. The system has a useful spectral range of 60GHz to 3 THz, corresponding to a wavelength range of 0.09–5mm...

More details at: http://onlinelibrary.wiley.com/doi/10.1002/jps.23560/abstract

Wednesday, 24 April 2013

Investigation on the Terahertz Absorption Spectra of the Molecules with Similar Molecular Structure

Conference Paper from Laser and Tera-Hertz Science and Technology

Wuhan, China, November 1, 2012
THz Spectroscopy and Imaging (SF3A)
Author: Wenhui Fan; http://dx.doi.org/10.1364/LTST.2012.SF3A.1
+The Optical Society (OSA)


The characteristic terahertz absorption features of several molecules with similar molecular structure have been measured by terahertz time-domain spectroscopy experimentally. Theoretical simulations have also been performed, and all measured terahertz absorption features are assigned.

More info at: http://www.opticsinfobase.org/abstract.cfm?URI=LTST-2012-SF3A.1

Monday, 22 April 2013

Characterisation of amorphous and crystalline domains using terahertz spectroscopy

M.E. Marlow2, H. Seker 2 and G. Smith1
1 School of Pharmacy and 2Centre for Computational Intelligence, +De Montfort University Leicester (DMU), UK,
3 School of Pharmacy, University of Nottingham, Nottingham, NG7 2RD, UK


The centre portion of the terahertz region has a unique combination of properties in that: many amorphous excipients are transparent or semi-transparent to terahertz radiation whilst many crystalline materials have characteristic spectral features. The research presented here is focused on developing methods for characterising crystalline and amorphous domains in drug products. A model system of tablets comprised of either Avicel® PH-101 or polyethylene (PE) (both transparent to terahertz) with lactose monohydrate have been used to evaluate terahertz spectroscopy methods in the transmission and reflection modes.

More info at: https://www.dora.dmu.ac.uk/xmlui/handle/2086/7930

... For both transmission and reflection  measurements the time domain signal was recorded using  the TeraView TPI 3000 (TeraView, Cambridge, UK). Terahertz images were obtained by raster scanning the  terahertz beam across the sample ...

Friday, 19 April 2013

6th UK, Europe, China Millimeter Waves and THz Technology Workshop

The UCMMT 2013 Committee is pleased to invite you to the UK, Europe, China Millimeter Waves and Terahertz Technology Workshop that will be held in Rome, Italy on 9-11 September 2013.

Key dates:

Submission of abstract: Wednesday 15 May
Notification of acceptance: Wednesday 5 June
Early registration deadline: Monday 1 July
Final abstract submission: Monday 1 July

UCMMT was formerly UK-China Millimeter Waves and Terahertz Technology Workshop created in 2007 to stimulate and strengthen the cultural exchange between UK and China. In 2012 the Workshop, held in Nanjing, was extended to the mainland Europe, stating the importance of even closer collaboration for the progress of science and technology. UCMMT is held alternatively one year in China and one year in Europe.
UCMMT is a unique forum, where lead scientists from China, Europe and United Kingdom share their knowledge in the field of millimeter waves and THz sources, devices, systems and applications.
A special issue of the International Journal of Terahertz Science and Technology will be dedicated to extended versions of papers from UCMMT2013.

More details at: http://ucmmt2013.lancs.ac.uk/

Thursday, 18 April 2013

Impact of Pellet Thickness on Quantitative Terahertz Spectroscopy of Solid Samples in a Polyethylene Matrix

Anal. Chem., 2013, 85 (7), pp 3674–3681
DOI: 10.1021/ac302017d
Publication Date (Web): February 25, 2013
Copyright © 2013 +American Chemical Society

Authors: Hankyu Namkung †, Jaejin Kim †, Hoeil Chung *†, and Mark A. Arnold *‡
† Department of Chemistry and Research Institute for Natural Sciences, Hanyang University, Seoul, Korea 133-791
‡ Department of Chemistry and Optical Science and Technology Center, University of Iowa, Iowa City Iowa 52242, United States


Pellets composed of different weight-percent (wt-%) of lactose within a polyethylene (PE) matrix are used to examine how the physical thickness of solid samples impact analytical measurements performed over terahertz (THz) frequencies when using time-domain THz spectroscopy. Results indicate that the thickness of each pellet depends on the mass and physical properties of the individual components that comprise the pellet. Thickness of mixture pellets depends on the porosity of the individual pellet components. Porosity measurements presented here for PE and lactose give values of 25.6 ± 0.3 and 14.5 ± 0.1, respectively, which indicate that more air is trapped within the compressed PE matrix compared to that for lactose. This difference in porosity creates different pellet thicknesses for pellets of the same nominal mass but with different relative amounts of PE and lactose. For this binary matrix, the thickness of each pellet is found to be a linear combination of the compressed densities of the individual components. Analysis of the time-domain THz spectra reveals that thinner samples are confounded by a fringe pattern observed in the frequency-domain spectra. This fringe pattern is created by an etalon corresponding to the air/pellet interfaces for the sample in the optical path. Spectra collected from thicker pellets are confounded by a sloping baseline caused by scattering effects within the pellet matrix. The quantitative impact of pellet thickness is determined by comparing the mean standard error of calibration (MSEC) and mean standard error of prediction (MSEP) for a set of leave-three-out cross validation multivariate calibration models based on the partial least-squares (PLS) algorithm. Results indicate that PLS models are capable of analytical measurements with MSEC and MSEP values between 0.04 and 0.20 wt-%. Analysis of spectral variance captured within the corresponding spectral loadings for each model indicates that spectral variance is lowest for the 300 mg samples where the impact of scattering is minimal under conditions when the sample etalon is nonexistent.

... Each time domain spectrum was collected with a TPI Spectra 1000 spectrometer (TeraView, Cambridge, UK) with a resolution setting of 1.2 cm-1. A detailed description of the instrumentation can ...

Wednesday, 17 April 2013

Terahertz pulsed imaging as an advanced characterisation tool for film coatings—A review

International Journal of Pharmaceutics
Available online 6 April 2013

Authors: Miriam Haasera, b, c, Keith C. Gordond, Clare J. Strachane, Thomas Radesf
a School of Pharmacy, +University of Otago, P.O. Box 56, Dunedin, New Zealand
b Cavendish Laboratory, +Cambridge University Press Education , Cambridge CB3 0HE, UK
c +TeraView Ltd., St. John's Innovation Park, Cambridge CB4 0WS, UK
d Department of Chemistry, MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, Dunedin, New Zealand
e Division of Pharmaceutical Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
f Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark


Solid dosage forms are the pharmaceutical drug delivery systems of choice for oral drug delivery. These solid dosage forms are often coated to modify the physico-chemical properties of the active pharmaceutical ingredients (APIs), in particular to alter release kinetics. Since the product performance of coated dosage forms is a function of their critical coating attributes, including coating thickness, uniformity, and density, more advanced quality control techniques than weight gain are required. A recently introduced non-destructive method to quantitatively characterise coating quality is terahertz pulsed imaging (TPI). The ability of terahertz radiation to penetrate many pharmaceutical materials enables structural features of coated solid dosage forms to be probed at depth, which is not readily achievable with other established imaging techniques, e.g. near-infrared (NIR) and Raman spectroscopy. In this review TPI is introduced and various applications of the technique in pharmaceutical coating analysis are discussed. These include evaluation of coating thickness, uniformity, surface morphology, density, defects and buried structures as well as correlation between TPI measurements and drug release performance, coating process monitoring and scale up. Furthermore, challenges and limitations of the technique are discussed.

... The imaging unit in TPI instruments such as the TPI imaga 2000 system (TeraView, Cambridge, UK), therefore comprises a six-axis robotic arm, the probe and a separate optical laser operating at 670 nm. ...

More info at :http://www.sciencedirect.com/science/article/pii/S0378517313002834

Monday, 15 April 2013

Using Terahertz Spectroscopy for Observing the Kinetics of Recrystallisation of Polybutene-1

Journal of Infrared, Millimeter, and Terahertz Waves

February 2013, Volume 34, Issue 2, pp 187-193
doi: 10.1007/s10762-013-9956-8

Authors: V. Křesálek, T. Gavenda
More details at: http://link.springer.com/article/10.1007/s10762-013-9956-8


This paper deals with the use of terahertz spectroscopy for observing the kinetics of recrystallisation of polybutene-1 as a suitable material for manufacturing optical elements in the terahertz region of the electromagnetic spectrum. These materials were studied from the perspective of their optical properties – the refractive index and the absorption coefficient. The time dependencies of the refractive index and the absorption coefficient were measured, because polybutene-1 is a material which recrystallises for a number of days from the date of its manufacture. The coefficients describing the recrystallisation process were calculated from the fitting function derived from the Avrami equation. In this paper, the measurement results are presented and the possibilities of the use of the studied materials are discussed.

...Measurement was conducted by a TPSTM Spectra 3000...Thickness was measured at 12 points of each sample to achieve the desired accuracy, after averaging the measured values. The calculation of the refractive index and absorption coefficient was performed with the TPSTM Spectra 3000 software, with air as the reference value...

Thursday, 11 April 2013

Terahertz Spectroscopy and Imaging - New Book

Series: Springer Series in Optical Sciences, Vol. 171,2013, XXXI, 641 p.
Authors: Peiponen, Kai-Erik; Zeitler, Axel; Kuwata-Gonokami, Makoto (Eds.

More details at: http://www.springer.com/physics/optics+%26+lasers/book/978-3-642-29563-8
  • Presents the state-of-the-art of Terahertz spectroscopy
  • Gives a concise presentation of the basics of THz spectroscopy
  • Describes important applications of THz technology
"This book presents the current state of knowledge in the field of terahertz spectroscopy, providing a comprehensive source of information for beginners and experienced researchers alike whose interests lie in this area. The book aims to explain the fundamental physics that underpins terahertz technology and to describe its key applications. Highlights of scientific research in the field of terahertz science are also outlined in some chapters, providing an overview as well as giving an insight into future directions for research.

Over the past decade terahertz spectroscopy has developed into one of the most rapidly growing areas of its kind, gaining an important impact across a wide range of scientific disciplines. Due to substantial advances in femtosecond laser technology, terahertz time-domain spectroscopy (THz-TDS) has established itself as the dominant spectroscopic technique for experimental scientists interested in measurements at this frequency range. In solids and liquids THz radiation is in resonance with both phonon modes and hydrogen bonding modes, which makes it an ideal tool to study the interaction between molecules in a unique way; thus opening a wealth of opportunities for research in physics, chemistry, biology, materials science and pharmaceuticals.

This book provides easy access to scientists, engineers and students who want to understand the theory and applications of modern THz spectroscopy."

Chapter: Industrial Applications of Terahertz Imaging

This chapter gives a concise overview of potential industrial applications for terahertz imaging that have been reported over the past decade with a discussion of the major advantages and limitations of each approach. In the second half of the chapter we discuss in more detail how terahertz imaging can be used to investigate the microstructure of pharmaceutical dosage forms. A particular focus in this context is the nondestructive measurement of the coating thickness of polymer coated tablets, both by means of high resolution offline imaging in research and development as well as for in-line quality control during production.

... Defect in copper trace (a) (b) Fig. 18.3 Electro Optical Terahertz Pulse Reflectometry (EOTPR) for semiconductor fault testing. a Optical images of the two failed devices showing the cut in the copper traces. b Results obtained with EOTPR (source: TeraView Ltd.) ...

More on applications of terahertz technology http://www.teraview.com/applications/index.html

Wednesday, 10 April 2013

Evaluating the effect of coating equipment on tablet film quality using terahertz pulsed imaging

European Journal of Pharmaceutics and Biopharmaceutics,

Authors: Miriam Haasera, b, c, 1, Kaisa Naelapääd, 1, Keith C. Gordone, Michael Pepperb, f, Jukka Rantanend, Clare J. Strachana, g, Philip F. Tadayb, J. Axel Zeitlerh, Thomas Radesa, d
a School of Pharmacy, University of Otago, Dunedin, New Zealand
b +TeraView, St. John’s Innovation Park, Cambridge, UK
c Cavendish Laboratory, +Cambridge University Press Education, Cambridge, UK
d Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
e Department of Chemistry, MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, New Zealand
f Department of Electronic Engineering, +UCL, Torrington Place, London, UK
g Division of Pharmaceutical Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
h Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK


TPI imaga 2000In this study, terahertz pulsed imaging (TPI) was employed to investigate the effect of the coating equipment (fluid bed and drum coater) on the structure of the applied film coating and subsequent dissolution behaviour. Six tablets from every batch coated with the same delayed release coating formulation under recommended process conditions (provided by the coating polymer supplier) were mapped individually to evaluate the effect of coating device on critical coating characteristics (coating thickness, surface morphology and density). Although the traditional coating quality parameter (weight gain) indicated no differences between both batches, TPI analysis revealed a lower mean coating thickness (CT) for tablets coated in the drum coater compared to fluid bed coated tablets (p < 0.05). Moreover, drum coated tablets showed a more pronounced CT variation between the two sides and the centre band of the biconvex tablets, with the CT around the centre band being 22.5% thinner than the top and bottom sides for the drum coated tablets and 12.5% thinner for fluid bed coated tablets. The TPI analysis suggested a denser coating for the drum coated tablets. Dissolution testing confirmed that the film coating density was the drug release governing factor, with faster drug release for tablets coated in the fluid bed coater (98 ± 4% after 6h) compared to drum coated tablets (72 ± 6% after 6h). Overall, TPI investigation revealed substantial differences in the applied film coating quality between tablets coated in the two coaters, which in turn correlated with the subsequent dissolution performance.

... Terahertz pulsed imaging measurements. A total of six randomly chosen tablets of every batch were imaged individually using the TPI Imaga 2000 (TeraView Ltd, Cambridge, UK) ... 

Tuesday, 9 April 2013

Terahertz and optical study of monolayer graphene processed by plasma oxidation

Appl. Phys. Lett. 102, 131901 (2013); http://dx.doi.org/10.1063/1.4795526
(Received 7 February 2013; accepted 26 February 2013; published online 1 April 2013)

Authors: Kyujin Choi1, Juhwan Lim2, J. R. Rani2, Hyong Seo Yoon2, Juyeong Oh2, Taeyoon Hong1, Taewoo Ha1, Byung Cheol Park1, Kyung Ik Sim1, Seong Chan Jun2, and Jae Hoon Kim1
1 Department of Physics and Institute of Physics and Applied Physics, +Yonsei University, Seoul 120-749, Republic of Korea 
2 Department of Mechanical Engineering, +Yonsei University, Seoul 120-749, Republic of Korea 


We report on our terahertz and optical study of monolayer graphene grown by chemical vapor deposition and processed by plasma oxidation. The plasma oxidation induces oxygen-related defects, and the resulting disorder increases the sheet resistance of graphene as measured via terahertz spectroscopy. The excitonic absorption peak weakens considerably and blue shifts upon plasma oxidation, resulting in higher transmittance in both the visible and ultraviolet regions. Our oxygen plasma-treated graphene also exhibits a free-carrier doping effect as confirmed by the blue shift of the Raman G band.

... Raman spectroscopy was performed with WITEC ALPHA300M Raman System (excitation at 532 nm, 2.33 eV). The VUV spectrophotometry was carried out with a Cary 5G spectrophotometer and THz-TDS with TeraView TPS Spectra 3000 ... 

More details at: http://apl.aip.org/resource/1/applab/v102/i13/p131901_s1?isAuthorized=no

More about terahertz equipment: http://www.teraview.com/products/index.html

Monday, 8 April 2013

Terahertz Conductivity of Twisted Bilayer Graphene

Physical Review Letters 110, 067401 (2013)  Received 9 April 2012; published 7 February 2013

Authors: Xingquan Zou1, Jingzhi Shang1, Jianing Leaw1, Zhiqiang Luo1, Liyan Luo1, Chan La-o-vorakiat1, Liang Cheng1, S. A. Cheong1, Haibin Su2, Jian-Xin Zhu3, Yanpeng Liu4, Kian Ping Loh4, A. H. Castro Neto5, Ting Yu1, and Elbert E. M. Chia1
  1. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
  2. Division of Materials Science, School of Materials Science and Engineering, Nanyang Technological University, 639798 Singapore
  3. Theoretical Division and Center for Integrated Nanotechnologies, +Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
  4. Department of Chemistry, +National University of Singapore , 3 Science Drive 3, 117543 Singapore
  5. Graphene Research Centre and Physics Department, National University of Singapore, 6 Science Drive 2, 117546 Singapore
More details at: http://prl.aps.org/abstract/PRL/v110/i6/e067401


Using terahertz time-domain spectroscopy, the real part of optical conductivity [σ1(ω)] of twisted bilayer graphene was obtained at different temperatures (10–300 K) in the frequency range 0.3–3 THz. On top of a Drude-like response, we see a strong peak in σ1(ω) at ∼2.7  THz. We analyze the overall Drude-like response using a disorder-dependent (unitary scattering) model, then attribute the peak at 2.7 THz to an enhanced density of states at that energy, which is caused by the presence of a van Hove singularity arising from a commensurate twisting of the two graphene layers.
© 2013 +American Physical Society

... The transmission THz spectra of the BLG were measured using a conventional THz-TDS system (TeraView TPS Spectra 3000)... THz TDS has proven to be a very useful noncontact technique to study material properties such as dielectric response, complex conductivity and refractive index in the far-infrared range without the need for Kramers-Kronig analysis ...

Thursday, 4 April 2013

Generation THz - an article from Dr Axel Zeitler

Original article from:

Dr Axel Zeitler, of the University of Cambridge’s Department of Chemical Engineering and Biotechnology, looks at the dramatic progress made in terahertz research in recent years…

Terahertz radiation has excellent potential to help with the understanding of fundamental and exciting new challenges at the interface between physics, materials chemistry and the life sciences. Examples include fields as diverse as non-destructive testing of composite materials such as wind turbine blades, semiconductor quality control and intraoperative probes for breast cancer surgery. However, light located in this range of the electro-magnetic spectrum was very difficult to generate until quite recently, and so the full potential of these exciting applications is only just starting to emerge.

There can be no doubt that the main reasons for the surge in interest in performing spectroscopy at terahertz frequencies were the development of ultrafast lasers and the discovery of the Auston switch. These technologies made it possible to provide light at terahertz frequencies (a frequency of 1 THz equals a wavelength of 0.3 mm) in a relatively simple way. They enabled the development of a new generation of spectrometers in the early 1990s that were able to generate and detect pulses of coherent terahertz radiation with previously unprecedented ease and sensitivity. Today, most of the research in terahertz spectroscopy and imaging is carried out using such time-domain spectrometers. Terahertz time-domain spectroscopy (THz-TDS), therefore, is currently the main focus of research activities in the terahertz community.

There is no commonly agreed definition of the upper and lower frequency limits of terahertz (THz) radiation. Its spectral range overlaps with the far infrared at the higher frequency end and the microwave region at lower frequencies. The term thus refers to a relatively narrow part of the electro-magnetic spectrum. Despite this narrowness, which it shares, for example, with visible light, terahertz radiation is of great importance in terms of fundamental research as well as in technology and the life sciences. And yet, whilst nobody would question the importance of research involving radiation such as visible light, until recently research into terahertz radiation has been relatively obscure.

Terahertz radiation has unique properties in that it easily penetrates through most polymeric and ceramic materials and is therefore an exciting new tool to study such materials, which are often opaque at visible frequencies. This transparency of terahertz radiation to non-polar and non-metallic materials motivates the use of terahertz radiation in security screening and industrial quality control applications. As well as being a non-destructive probe of materials in organic molecular crystals such as drug molecules, terahertz radiation has the important property of interacting with vibrational modes that extend across large domains of a crystal lattice. This makes terahertz spectroscopy unique: even though it is possible to excite molecules using a variety of energies, it is only through the careful selection of the low energy in the terahertz range that it is possible to selectively excite crystal lattice vibrations and study in a unique way the presence and nature of interactions between molecules.

A wide range of further significant microscopic physical phenomena can be found in the terahertz regime. Bulk dielectric relaxations and intermolecular motions occur in this spectral range. Critical frequencies for Debye relaxation processes in many liquids fall into the terahertz regime. Pure rotational transitions occur when polar gases are stimulated by terahertz radiation. Moderately doped semiconductors have their plasma frequencies and damping rates defined between 0.1 and 2THz.

Terahertz research continues to mature at rapid pace and commercial instrumentation is now readily available. This has made it possible for the field to expand from a niche technology in semiconductor physics to an exciting mainstream research and sensing platform with a broad variety of applications, from fundamental research to industrial process control.

Dr Axel Zeitler
Head Terahertz Application Group
Department of Chemical Engineering and Biotechnology
University of Cambridge

Over the years TeraView has successfully collaborated with Dr. Zeitler at the Department of Chemical Engineering and Biotechnology, University of Cambridge. Dr. Zeitler purchased a TPI imaga 2000 and is currently working with TeraView on advancing the industrial applications of terahertz technology into process control, manufacturing and real-time data generation in industrial conditions.

The collaboration between Dr. Zeitler and TeraView goes back many years as he completed his PhD Thesis Physical Characterisation of Pharmaceutical Solids by Terahertz Pulsed Spectroscopy and Imaging, working with TeraView's Applications Group lead by Dr Phil Taday. 

For a full list of his publications visit: http://www.researcherid.com/rid/B-4885-2008

Wednesday, 3 April 2013

Towards optoelectronic detection of explosives

Opto-Electronics Review, June 2013, Volume 21, Issue 2, pp 210-219
doi 10.2478/s11772-013-0082-x

Authors: J. Wojtas, T. Stacewicz, Z. Bielecki, B. Rutecka, R. Medrzycki, J. Mikolajczyk
More details at: http://link.springer.com/article/10.2478/s11772-013-0082-x


Detection of explosives is an important challenge for contemporary science and technology of security systems. We present an application of NOx sensors equipped with concentrator in searching of explosives. The sensors using CRDS with blue — violet diode lasers (410 nm) as well as with QCL lasers (5.26 μm and 4.53 μm) are described. The detection method is based either on reaction of the sensors to the nitrogen oxides emitted by explosives or to NOx produced during thermal decomposition of explosive vapours. For TNT, PETN, RDX, and HMX the detection limit better than 1 ng has been achieved.

... Time domain spectroscopy (TDS) is especially useful in the THz range [12,13]. Observation of explosives' transmission and reflection are conducted by using TeraView TPS Spectra 3000 instrument at the Institute of Optoelectronics, MUT ...

Author Affiliations: Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Str., 00-908, Warsaw, Poland

In 2011 TeraView supplied two TPS Spectra 3000 systems with a stand-off explosives detection module and a fibre-fed scanning system with multiple gantry options for research into terahertz imaging and non-destructive testing. Military University of Technology (MUT) in Poland is one of the country’s most prestigious research institutes for terahertz research and materials characterisation. Read more...