0908_Complete_rev8:Layout 1 10/08/2009 14:42 Page 20
Explosive Detection
vibrational or rotational motions of technology for airport and homeland “...software can work in
molecules in the sample, the particular security, most notably Quantum Cascade
molecule and its environment will Lasers (QCL) for trace gas detection in conjunction with X-ray
determine which Raman signals will be the continuous-emission monitoring
observed. A plot of Raman intensity vs. market. Cascade Technologies has machines to analyse
Raman shift is a Raman spectrum. developed a QCL-based trace gas sensor
The Raman spectrum of a sample is for detecting vapours of explosives with substances pixel by pixel
collected and then matched against the support from the UK Home Office
stored Raman library – a catalogue of Scientific Development Branch (HOSDB). and alert personnel when
explosives, chemicals, and industrial The research centred on selecting
materials as well as illegal drugs, which several explosive compounds such as the analysis of an object
can be updated and augmented. nitroglycerine (NG) and ethylene glycol
Samples can be analysed on the spot, dinitrate, using a novel ‘sniffer’ platform in a carry-on bag has the
thereby preventing exposure to system based on the use of QCL.
chemicals or disturbing scenes for These are semiconductor lasers "pixel signature" of an
Turning Challenges into Opportunities: Achieving More with Less
forensic analysis. developed by a number of companies
Raman spectroscopy is becoming an and research units that emit in the mid- explosive material...”
affordable tool. In the past it required to far-infrared portion of the
Cape Town, South Africa
costly equipment and experienced electromagnetic (EM) spectrum. The QC High-resolution spectroscopy coupled
spectroscopists, and proved impractical laser uses nano-sized crystals to harness with laser wavelength selectivity offers
as an analytical technique in field the power of a laser source spanning the the substantial benefit of significantly
1 0 – 1 2 N o v e m b e r 2 0 0 9
applications when extensive training is full spectrum of the technologically decreasing false-positives. The QC laser
required. These extra overheads obviated significant mid-IR wavelengths (3-25 can also detect IED precursors in pre-
the cost advantage of the handheld μm), where most chemical fingerprints or defined levels – this is vital in avoiding
instruments. Novel analytical techniques absorption features can be found. These false positives from passengers who
such as fibre-optics–based oxygen absorption features allow unambiguous carry commonly available items that
sensors and laser-induced breakdown identification fingerprinting results from often contain precursor traces.
spectroscopy are now propelling the low- rotational vibrational transitions of atoms QCL may give instantaneous results
resolution Raman spectroscopy (LRRS) within the molecules. and be deployed in a portal to screen
applications markets. Preliminary studies on the technology 100% of passengers at walking speed.
The stage is set for the most important
Ahura Corporation's FirstDefender was have indicated that direct fingerprinting It is expected to become commercially
one of the first Raman devices to come (detection – identification) of explosive available pending trials by an
onto the market. A handheld liquid- compounds and tagging agents by undisclosed large security company. aviation security event of the year
explosives detector, it weighs about 1.6 kg sniffing surrounding ambient air is The price of the technology is, as yet,
and costs $30,000. The TruDefender™ FT achievable, as is detection of such also undisclosed but clients are
launched in 2008 has similar specs and compounds on packaging used to ship expected to include those security
incorporates FTIR, to complement the the sealed compounds, making this companies that specialise in airport
earlier Raman instrument. The new platform a strong contender for detection screening procedures.
generation of LRRS is being exploited by of cross-contaminated materials. It was Of course, such new technologies can
leaders in detection industry such as GE also possible to detect breakdown be circumvented by terrorists developing
and Smiths to provide rapid, non-invasive, products associated with sample NG. new substances that cannot be detected
non-destructive chemical analysis of by the proposed technology, or by
aqueous solutions, powders, tablets, gels, following special procedures that would
and surfaces. prevent residual vapours from being
These applications utilise Raman released into the surrounding air. As ever,
spectroscopy as the ‘optical engine’ in therefore, methods to complement
materials analysers or chemical detection technologies, such as
detectors. A chief advantage of the passenger profiling and other
newer types over the first ones is that intelligence-based work, are vital to not
they can detect and identify chemicals, only to prevent terrorists getting
explosives, and their components explosives through but to deter at least
through glass and plastic containers. some of them from trying.
False alarm rates can also be
minimised through identification of less Andy Oppenheimer is a CBRNE
dangerous but very similar specialist and Contributing Editor to
microorganisms or materials. Domestic Preparedness journal. He is
the former Editor of Jane’s Nuclear,
Quantum Cascade Lasers Prototype passenger screening portal Biological and Chemical Defence and
(QCL) using Quantum Cascade Lasers author of IRA: the Bombs and the Bullets
Laser-based solutions for explosives and (Credit: Cascade Technologies) (Irish Academic Press).
precursor detection are a promising new
20 Register now for FREE instant access to ASI online by visiting www.asi-mag.com August 2009 Aviationsecurityinternational
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54