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They're more commonly seen on the side of drinks cans or on adverts to direct you to company websites. But now QR codes - the fuzzy squares of data that can be scanned with a smartphone - could be projected into the sides of tanks to send covert information, using only heat.
Defence firm BAE Systems has developed a technology called Adaptiv, which uses hexagonal tiles that can change temperature to hide or even disguise a tank's infra-red signature. At the defence industry exhibition (DSEI) in London, UK, BAE demonstrated how input from a tank's on-board software can heat or cool the individual tiles to either hide the vehicle from enemy infrared sensors. Because each tile can be individually heated or cooled, the system can also project the infrared image of other objects onto the side of the tank; a car for example, or even just a pile of rocks.
Within seconds of the flick of a switch, some of the tiles felt noticeably warmer to the touch and an infrared camera showed that the word "Adaptiv" was now visible across the vehicle's flank, each letter glowing white against the grey background on the camera, indicating that it was hotter than its surroundings.
The tank's own on-board thermal camera can also be used to take a picture of the background heat signature of a particular location and then feed it to the software that controls the temperature of the tiles - helping the tank match its background, and effectively disappear from view.
BAE's Peder Sjolund says that because a number of available pre-set patterns can be stored on board the tank's computer system, the tiles could even be used to communicate by using them like pixels to spell out coded messages in the form of a QR code.
While each tank will carry round 1500 tiles when the technology is used for real by the military, the demonstration tank was only fitted with 400 tiles. Still these are enough to encode 500 characters in a QR code, says Sjolund.
The next step is to develop a similar system for boats as well as continuing work on ways of re-using the heat that is pulled off the tiles when they are rapidly cooled - perhaps to re-use it as power, says Sjolund.
Niall Firth, New Scientist
