BRAND-NEW
UC Berkeley Researchers Developed Coatings that Can Create False Infrared Images In a paper published in the journal Advanced Materials, two UC Berkeley researchers described how 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. This kind of technology could prove useful for military and intelligence agencies to ensure national security.
I
nfrared light is invisible to the human eye, but can be detected by a
inherently self-adaptive to temporal fluctuation as well as spatial variation
range of devices, such as night-vision goggles and thermal-imaging
of the target temperature.
cameras. The coatings developed by Junqiao Wu, UC Berkeley
Additionally, by manipulating the configuration and composition of
professor of materials science and engineering, and post-doctoral
tungsten-doped vanadium dioxide on coatings applied to the PE tape,
researcher Kechao Tang can effectively tune target objects into emitting
researchers can create an infrared decoy.
the same infrared radiation as the surrounding environment, making
“How we grow the material changes the image people ultimately think
them invisible to infrared detection devices.
they see,” said Junqiao Wu.
Moreover, the coatings, which are made from delicately engineered thin films of tungsten-doped vanadium dioxide, can be manipulated in a way
The testing process
that a person trying to view the object with such a device would instead
In the paper, researchers described encoding the letters C-A-L onto
see a false image.
samples that they later placed on the surface of an object. The colour of
Tungsten-doped vanadium dioxide is a substance that at certain
the letters represents the temperature people see when viewing from an
temperatures can phase shift from an insulator, which suppresses electric
infrared camera. For example, the blue C shows it is at a constant 5°C,
conductivity, to a metal, which conducts electricity.
the lighter blue A at a constant 15°C, and the green L at a constant 25°C,
The insulator-metal phase transition can even out, allowing the substance
regardless of the actual temperature of the samples.
to emit a constant level of thermal radiation over wide range of
Even though the object’s actual temperature varies widely from 35-65
temperature variations (15-70 degrees Celsius). This state of equilibrium
degrees Celsius, a person who views the object through night-vision
prevents a camera from detecting the true infrared signals that an object
goggles will distinctly see a colder “CAL” that is independent of the actual
normally emits around room temperature.
temperature. © UC Berkeley
“We can both erase real information and create
How the coatings were developed
false information,” Wu said, “CAL stays cool when the
Berkeley researchers, backed by the National
environment is hot.”
Science Foundation and the Bakar Fellows
This kind of technology could prove useful for
Program, grew ultra-thin layers of vanadium
military and intelligence agencies, as they seek
dioxide (less than 100 nanometres thick) on
to thwart increasingly sophisticated surveillance
structures made from borosilicate glass and
technologies that pose a threat to national security.
sapphire. Using pulsed lasers, researchers doped
It might also incubate future encryption technology,
the films with different amounts of tungsten and
allowing information to be safely concealed from
then transferred the material onto a polyethylene
unauthorized access.
(PE) film tape. The researchers say this method provides better, more consistent camouflage because the
Coatings tune target objects into emitting the same infrared radiation as the surrounding environment.
product is mechanically flexible, power free and
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N. 65 - SEPTEMBER/OCTOBER 2020 - international PAINT&COATING magazine
For further information: www.engineering.berkeley.edu