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Infrared light is invisible to the human eye, but can be detected by a range of devices, such as night-vision goggles and thermal-imaging cameras. Researchers from Berkeley have found a way to imbed visual “decoys” into surfaces of objects in a way that can fool people into thinking they detect a specific image in the infrared that actually isn’t there.
The technology could prove useful for military and intelligence agencies, as they seek to thwart increasingly sophisticated surveillance technologies that pose a threat. It might also incubate future encryption technology, allowing information to be safely concealed from unauthorized access.
The researchers described a process in which they created special structures made from delicately engineered thin films of tungsten-doped vanadium dioxide.
The coatings developed by Berkeley researchers can effectively tune target objects into emitting the same infrared radiation as the surrounding environment, making them invisible to infrared detection devices.
But what makes the researchers’ work particularly novel is that they can manipulate the coatings in a way that a person trying to view the object with such a device would instead see a false image.
Tungsten-doped vanadium dioxide is a substance that at certain temperatures can phase shift from an insulator, which suppresses electric conductivity, to a metal, which conducts electricity.
With judicious engineering of the doping profile, the insulator-metal phase transition can even out, allowing the substance to emit a constant level of thermal radiation over wide range of temperature variations (15-70 degrees Celsius). This state of equilibrium prevents a camera from detecting the true infrared signals that an object normally emits around room temperature, according to phys.org.
The paper was published in the journal Advanced Materials.