COVID-19 has revolutionised security practices along with other parts of everyday life: screening people via personal ‘patdowns’ is no longer safe. ESA-developed passive terahertz technology – enabling the detection of items hidden under clothing from a distance – is helping to fill the gap. The US Customs and Border Protection agency is among the latest of more than 200 users of the technology, deploying it to secure the US border.
Those being screened do not have to walk into any special booth, but simply walk past the detector, without even noticing. They are not exposed to any radiation; instead the system relies on passively measuring terahertz radiation emitted by anything sufficiently warm, including the human body – a region of the electromagnetic spectrum first employed by satellites observing the Earth and deep space.
The technology has been commercialised by UK company Thruvision, with customers including airports around the world and the LA Metro as well as the US Customs and Border Protection agency, at selected southern border ports of entry.
“By detecting heat energy coming from a human body, we can easily spot detect any concealed items on a person that are blocking that energy,” explains Colin Evans, CEO of Thruvision. “It’s the functional equivalent of looking at someone with night vision goggles, except at a much lower frequency.”
The global logistics and supply chain industry represents another focus of interest for passive terahertz screening. The massive distribution centres that serve the fast-growing e-commerce sector, staffed by thousands of employees, have proved attractive targets for theft by organised crime and individuals.
Traditionally such centres perform randomised employee patdowns using portable metal detectors, which are intrusive, unpopular and thanks to the COVID-19 pandemic, unsanitary. They are also ineffective, being unable to detect non-metallic objects.
Instead SONY Digital Audio Disc Corporation, the manufacturing logistics arm of SONY Corporation has begun using the passive terahertz system to routinely screen all its distribution centre workers. Operating from a distance of 3 m away, the technology can even detect very small metallic and non-metallic objects, such as CDs, cell phones or USB drives.
“We’re very proud to be using ESA’s technology to help businesses and workers continue to be productive, despite the COVID-19 pandemic,” adds Colin Evans.
Terahertz and sub-mm waves are employed in space in various ways, to image early galactic evolution and perform temperature and humidity sounding for weather forecasting and research.
Their use down on the ground dates back to the start of this century, when ESA and the UK’s Rutherford Appleton Laboratory (RAL) collaborated on shrinking detectors down to an easily portable size, able to image items from a few metres away rather than far away in space.
“Since the early days of terahertz scanning, significant technological steps have been made,” explains Peter de Maagt, head of ESA’s Antennas and Sub-mm Waves Section, and co-author of the patent. “The scanning technology is now available at commercially affordable prices that allow widespread use.”
The ensuing patent is owned jointly by ESA and RAL, subsequently licensed by ThruVision.
“It’s a big success for us when a space invention finds wider uses, and this ThruVision’s success is a notable example,” comments Aude de Clercq, heading ESA’s Technology Transfer and Patent Office. “ESA’s overall intellectual property rights portfolio consists of around 560 patents, available for licensing by European companies for both space and terrestrial applications.”