麻豆传媒

AT SOME roadside checkpoints in Iraq there are still guards who will point a handheld device at people, cars and trucks in the hope its antenna will twitch to reveal the presence of a bomb. But the contraption doesn鈥檛 work; it鈥檚 just a radio aerial swinging on a handle. Unfortunately, the message about its deadly ineffectiveness hasn鈥檛 reached all its users.

Last week, James McCormick, whose company made 拢50 million selling the fake bomb detectors for up to 拢27,000 each, was jailed for 10 years for what a judge at London鈥檚 Old Bailey called a 鈥渃allous confidence trick鈥� that resulted in dozens of deaths after cars containing bombs were waved through checkpoints where the device was being used to screen for explosives.

But there is some good news in the field of bomb detection. As McCormick was being jailed, the European Commission鈥檚 innovation arm announced the successful creation of a much more believable bomb-sniffing device. Created by a consortium funded by the EC, the portable laser rig is claimed to detect as little as 1 microgram of explosives from up to 20 metres away.

鈥淣o other research organisation or company has to date achieved similar breakthrough results,鈥� says Paul Codd, a spokesman for the project, known as Optical Technologies for the Identification of Explosives (OPTIX).

The system works by firing laser pulses at objects like door handles, windows, luggage or steering wheels to detect the traces of explosives that would-be bombers leave behind after handling bombs. It can be mounted in a van or on a mobile robot.

聯The system fires a laser at door handles to detect the traces of explosives left by would-be bombers聰

Just a few years ago, such an announcement would have been met with scepticism worthy of McCormick鈥檚 bomb-dowsing device. The problem was that, outside of pristine lab conditions, available laser technology was foiled by the presence of environmental contaminants.

OPTIX gets around this by combining two methods that didn鈥檛 work alone: laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy. In LIBS, a high-energy laser is fired at a target 鈥� a suspicious car door handle, say. This causes any residue to turn into a plasma that emits certain wavelengths of light, which reveal the elements in the residue. The molecular makeup of a residue can be worked out using the Raman technique, because the laser induces vibrations that are unique to each chemical compound. Combining the two pieces of information allows technicians to work out if the residue is from an explosive.

As one might expect, it isn鈥檛 without risk. 鈥淐aution is required when directing laser beams at explosives, since a beam of sufficient intensity and appropriate wavelength can cause them to ignite or detonate,鈥� says Sidney Alford, founder of bomb disposal equipment maker Alford Technologies in Chippenham, UK. But he thinks OPTIX will be safe, if used carefully. 鈥淧rovided the laser is aimed only at trace quantities of explosive, this problem should not arise,鈥� he says.

鈥淭he [new] trace explosives detector will increase security in all scenarios,鈥� says Alberto Calvo, a director at Indra Sistemas, part of the OPTIX consortium. But given recent events, it might be worth withholding judgement until trials, now underway with police bomb squads across Europe, come back with unassailably positive results.

This article appeared in print under the headline 鈥淎n explosive situation鈥�