Sensors and bombs

Sensor networks are the lifeblood of process control but their uses are expanding beyond this. In Europe the Fraunhofer Institute for Applied Solid State Physics IAF is developing an imaging laser technology that will allow a precise localisation of the dangerous substances which will assist users to detect illicit production of explosives and improvised explosive devices (IEDs).

Bombs are pretty easy to manufacture - all that is needed is a few aids and some easily accessible materials such as synthetic fertiliser - and security forces do not always succeed in preventing the attacks and tracking down illegal workshops in time.

But bomb manufacturing leaves its traces: remains of the synthetic fertiliser stick to stairs and doorknobs, and waste from the manufacturing process gets into the sewerage and is deposited in air ducts. Until now, no technology for systematically discovering illegal bomb production in an early stage has been commercially available. Researchers have now developed a sensor network as part of the EU project ‘EMPHASIS’ (Explosive Material Production Hidden Agile Search and Intelligence System), which can detect such activity early on and locate it precisely. Last week, they showed how a simple kitchen used to manufacture explosives can be tracked down at the test site of the Swedish Defence Research Agency (FOI) near Grindsjön in southern Sweden.

Different sensors send data to command centre

To keep the rate of false alarms as low as possible, different sensor technologies for early and precise localisation of illegal bomb manufacturing are implemented. The sensors are placed at different locations such as on apartment buildings or in sewers. Thus waste produced during the manufacturing of explosives and bombs can be detected early on. In the command centre, the data from all sensors is collected and automatically analysed. Suspicious results trigger the alarm. With the help of laser-based measurement techniques, security forces can then localise the bomb workshop from a distance. The infrared laser system of Fraunhofer IAF in Freiburg evaluates the data from the spectroscopic measurements directly and shows the results on a monitor.

“Our laser technology can reliably detect even faint traces of dangerous substances from a distance of about 20 metres,” says Dr Frank Fuchs, who leads the project at Fraunhofer IAF. “This reduces the safety risk for the operational forces. The implemented quantum cascade lasers emit in the infrared area and so do not endanger the human eye. The wavelength area between 7.5 and 11 micrometres is well suited for sensorics anyway: the molecules of organic compounds absorb very strongly in these wavelengths. Chemical compounds show specific absorption lines in this area. They can thus be exactly determined using these characteristic ‘fingerprints’.

Quantum cascade lasers can solve many of sensorics’ problems

Laser-based spectroscopy combined with a real-time visualisation of the measurement results will solve many of sensorics’ problems in the future. At airports or train stations, laser technology can be implemented to check suspicious luggage for explosives. It also promises quick and precise spectroscopic measurements without costly laboratory examinations when controlling food, medicine or drinking water. The source of pollution could be found more quickly in factories and production halls. “Quantum cascade lasers can principally be used wherever the chemical nature of a surface or its change through pollution is of interest,” says Fuchs. “As our lasers are widely tuneable, they can be adapted specifically for different issues and be the basis for highly sensitive sensors in different applications.”

About the project

The goal of EMPHASIS is to develop and test a system concept for detecting ongoing illicit production of explosives and improvised explosive devices (IEDs) in urban areas. The project is funded by the EU as part of the Seventh Framework Programme (FP7). Under the coordination of the Swedish Defence Research Agency FOI, the following partners are working on the project: the Fraunhofer Institutes for Applied Solid State Physics IAF and for Chemical Technology ICT, the Netherlands Organisation for Applied Scientific Research TNO, the Institut National de Police Scientifique from France and the companies Cascade Technologies from Scotland, Morpho S.A. from France as well as VIGO System S.A. from Poland.