Drones now need protection Erik Simonsen/Getty

Lasers have entered the arms race. As more countries equip their militaries with high-energy laser weapons, new defences are needed. Enter Helios, an anti-laser laser that aims to protect drones and other vehicles.

Laser weapons have been around for a few decades, but they are becoming much more widely used. The US military has large numbers of hand-held and vehicle-mounted lasers that it can use to dazzle the enemy, for example. And its warship USS Ponce now carries lasers powerful enough to shoot drones out of the sky.

It is not just the US military that has lasers. In August, the Ukrainian border guard service said that three of its guards experienced retinal burns while observing separatist activity through binoculars. They believe that a laser was used against them. This followed an earlier incident in which the service said that one of its reconnaissance aircraft was targeted by a Russian soldier with a hand-held laser in Crimea. “If this trend continues, it is an escalation of the conflict,” says California-based defence analyst and author Robert Bunker.


The USS Ponce’s laser can shoot down aircraft U.S. Navy photo by John F. Williams/Released

To defend against military lasers, Adsys Controls of Irvine, California, has created Helios, which can be carried on drones. To do much damage, an offensive laser needs to remain focused on its target for several seconds. Helios stops a laser from doing this by disrupting the systems controlling the beam – the Achilles’ heel for all such weapons. “Beam control is a critical function of high-energy lasers,” says Adsys CEO Brian Goldberg.

Helios can detect an incoming laser beam and identify its key characteristics, such as power, wavelength, pulse frequency and its source. Helios then interferes with the beam control – possibly by firing back a low-power laser of its own – so the attacking laser cannot fix on the target. “It provides permanent protection,” says Goldberg. “It’s not just buying time.”

He will not say exactly how the interference is done, but it may involve fooling the control system into thinking it is hitting its target despite the laser actually pointing a few metres to the side. A direct hit would have produced a big burst of reflected light, so a pulse sent back by an anti-laser laser could make it look like the original laser was on target.

But Helios could be susceptible to the same trick, says Roland Smith, a plasma physicist at Imperial College London. “If it puts out enough power to disrupt targeting, that makes it visible and a target itself,” he says. “If the laser weapon knows it is being jammed, it could engage the jammer.”