Airport scanner technology uses X-ray diffraction to identify materials and detect explosives

The scanner, which is being developed by researchers at Nottingham Trent and Cranfield Universities, can identify the presence of hidden explosives or illegal drugs in milliseconds.

The conventional X-ray scanners used in airports produce an image of an object and can identify broadly whether it consists of metal or organic material, but they cannot determine definitively what substance it is made from, according to Prof Paul Evans at Nottingham Trent University.

“You therefore have problems discriminating between explosive substances and other substances,” said Evans, who developed the technology alongside Prof Keith Rogers at the Cranfield Forensic Institute.

This can lead to false alarms, where passengers and their items must be searched by hand, slowing down security checks and creating long queues of frustrated passengers.

The new technology, known as Halo, uses the way an object diffracts, or scatters, X-rays to identify precisely what it is made of, in just 100 milliseconds.

X-ray diffraction is used widely in laboratories to identify materials. However, the process traditionally uses a thin beam, low power X-ray, which takes a long time to collect the desired information.

Instead, the researchers use high power but hollow X-ray beams, in the shape of a conical shell. When this hollow beam intersects the object to be scanned, the object itself focuses the scattered X-rays into a pattern inside the shell, where they can be detected, according to Evans.

“Our beam intersects the object, and concentrates the signal, so we can place various detectors inside the hollow beam, and see these unique patterns of diffracted radiation,” said Evans. “Our aim is to ultimately produce a device that will not only produce signals, but also reconstruct three-dimensional images from these signals,” he adds.

The universities have created a spin-out company, Halo X-ray Technologies, to commercialise the scanner. The company this month produced its first prototype device, suitable for scanning small portable objects such as parcels, envelopes, smartphones and tablets.

“We can produce a signal from these types of devices very quickly,” said Evans.

The researchers are also planning to develop more advanced versions of the technology that will be able to scan larger and more complex objects such as suitcases.

The technology could also be used in medical applications, for measuring bone density, for example, and in manufacturing for detecting and diagnosing problems on the production line.