Chinese military invents smart shield designed to make laser weapons useless, SCMP, Jan. 12, 2023.
Metallic film prevents missiles from being blinded by defence systems while maintaining clear view of targets, researchers say
Experiments suggest vanadium coating could deflect 90 per cent of a beam’s energy, reducing sharp glare to small bright spot, according to paper
Military researchers in southeastern China say they have created a material that can prevent missiles from being blinded by laser defence systems while maintaining a clear view of their target.
A lot of high-value military hardware – from Apache attack helicopters to Air Force One – is equipped with laser weapons that can fire a beam to deflect a homing missile.
Most of these defence systems cannot destroy the missile itself, but the beam can produce a large and intense glare on its infrared sensor, causing the missile to lose its target.
Professor Lu Yuan and his colleagues at the National University of Defence Technology in Hefei developed a smart film that is entirely transparent when applied to the lens of an infrared sensor but highly effective at blocking harmful light.
When the missile senses a laser beam, the film turns into a metallic shield that can reflect most of the beam’s energy away like a mirror, according to the researchers.
“This phase-change property can protect infrared thermal imaging systems from laser interference,” Lu’s team said in a paper published in the peer-reviewed Journal of Electronic Measurement and Instrumentation on Tuesday.
Laser-proof coating for sensors has been around for decades. In some countries, including the US, it is required for military hardware.
Materials such as ceramic can absorb a beam’s energy efficiently. But most coatings only work within a narrow range of laser wavelengths. Adding multiple layers of different coatings can help, but it can also block the missile’s view and reduce the sensor’s detection range and accuracy.
The Chinese team’s new coating uses vanadium, a silver-like metal primarily found in China, Russia and South Africa.
When heated, the vanadium can transform the coating from transparent and semi-conductive into a light-blocking, metallic state.
According to Lu’s team, other research teams have developed similar vanadium coatings before, but the phase change in these prototypes was slow and unreliable because the temperature was controlled by an external heat source such as electric wires.
To solve the problem, the Chinese researchers created a thin vanadium film over a composite made of gallium nitride (GaN), a high-performance semiconductormaterial used in 5G smartphones and other consumer electronics.
The GaN bottom layer can precisely control the vanadium film’s temperature to ensure a quick response to a laser threat, according to Lu’s team.
Laboratory experiments suggested that the film could divert 90 per cent of the laser’s energy away from the sensor. This means that a blinding glare that nearly fills the missile sensor’s viewing zone could be reduced to a small bright spot, the researchers said.
“Although this energy still partially saturates the thermal imager, the saturation area is small and the thermal imager can still perform effective imaging observation of the target area,” they wrote in the paper.
A Beijing-based researcher studying laser-proof technology said using a vanadium coating was not a new idea. Some smart windows have used similar technology.
But making it work during combat under complex and rapidly changing conditions remains a huge challenge. “For some obvious reasons, the paper has withheld some important technical details,” said the researcher, who requested not to be named because of the sensitivity of the issue.
For instance, Lu’s team said the sensor could still get a clear and detailed view of the target when the vanadium shield was activated, but they did not explain how this was achieved.
Reducing the size of the glare is just the first step in foiling laser defence systems. As a missile closes in on a target, laser pulses can produce a string of light spots on the heat image, and these spots change significantly as the distance narrows. These disturbances can also confuse the missile and cause it to lose its target, according to the researcher.
Laser weapon technology has continued to advance as the arms race between China and the West heats up, bringing new challenges for missile sensors.
“A number of countries are testing new compact laser devices with high power output. At close range, these weapons may be able to generate enough energy to burn through a mirror,” the researcher said.