How the Military Will Be Revolutionized By Laser Weaponry



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It was only late last year Lockheed Martin announced it was exploring ways to put a laser on the F-35 Joint Strike Fighter. There is also consideration towards putting them in the AC-130 gunship and B-1 and B-2 bombers. The U.S. Navy has already fielded a laser weapon on the Austin-classUSS Ponce, and anticipates arming the rest of the fleet in the 2020 to 2021 timeframe. Meanwhile, the U.S. Army is looking for ways to use lasers to protect troops in the field from artillery shells, missiles, and drones. 

It's relatively easy to gauge how of how much damage a 155-millimeter artillery shell or 500 pound bomb will do. Both are munitions that release tremendous amount of energy when the chemicals inside of them explode. But even now as weaponized lasers become a reality, hardly anyone knows how they really work and what kind of damage they can do. 

Thanks to science fiction, laser weapons have been in the public consciousness for nearly a hundred years. In the 1930s, Buck Rogers and Flash Gordon comics and movie theater serials portrayed lasers as weapons decades before a working laser had even been invented. 

Unfortunately, fictional lasers such as the Star Wars laser blaster are totally wrong. Star Wars lasers fly through the air in bright colors and make a sizzling noise as they pass nearby. Their bolts of energy move so slow you can see them move. Finally, they actually make explosions on the surface of their target—like Greedo's chest for example. Lasers in the Star Wars universe essentially function like regular gun shells. The reality is about as different as one can imagine.

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LASER is an acronym that stands for "light amplification through the stimulated emission of radiation." Lasers work by exciting the atoms, molecules, or ions in a medium—think gases, chemicals, fibers, or diodes—until they emit light at exactly the same wavelength. That light is then channeled into a narrow beam by a resonator, and then directed at a target. 

In other words, lasers are essentially narrow beams of focused light that do damage by heating the target. They can burn holes in aircraft skins, the hulls of small boats, or the human body. They can heat artillery shells in midair, causing them to explode, or the storage containers at a fuel dump until the fuel ignites.

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The strength of a laser isn't expressed in pounds like an aircraft bomb, or the diameter of a howitzer barrel. Military lasers are rated by the electrical power they consume, in kilowatt—and eventually megawatt—range.

Dr. Kelly Hammett, Chief Engineer for Directed Energy at the Air Force Research Lab, told Popular Mechanics: "Lasers can deliver precise and tailorable effects against a wide class of targets near-instantaneously and at a very low cost per shot.  The type of gradual effects a 30 kW laser can deliver includes: deny, degrade, disrupt, and destroy of targets such as UAV's or small boats at a few kilometers range."

There are dozens of types of lasers, used in everything from your Blu-Ray DVD player to nuclear weapons. The AN/SEQ-3 Laser Weapon System the U.S. Navy deployed on the USS Ponce in 2014 is a solid state laser operating at 30 kilowatts. The Air Force wants to put a 150 kilowatt rare earth laser on an AC-130 flying gunship capable of burning a "beer-can sized hole" in a target. 

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Unlike their fictional cousins in video games and movies, lasers don't make a sizzling noise as they burn through the air. Lasers can also be invisible, unless they pass through a medium such as smoke or fog. Someone under fire from a laser weapon may not know they're under attack until holes start appearing in things, things get very hot, and ammunition starts exploding. 

Lasers are also fast: they move at the speed of light, or 186,000 feet per second. At shorter ranges, that eliminates the need to "lead" a target. Anti-aircraft guns, for example, must aim ahead of an enemy airplane to compensate for the speed of airplane and the time it takes for a projectile to reach the airplane. By contrast, lasers move almost instantaneously and could just be pointed at a target, the travel time being negligible. 

Once they hit their target, lasers do their damage by heating the target, quickly and with a lot of energy. A laser will burn through ship hulls, airplane skins, armored plate, and human skin, passing through to burn everything in its path. This rapid heating would cause fuel tanks to catch fire or explode, engines to burn out, the explosives in ammunition to detonate, and worse. Lasers burn the skin of aircraft and flying drones, causing them to become aerodynamically unstable and tumble out of the sky. 

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All of this means that lasers could end up doing more than traditional line of sight weapons, such as guns. A laser could heat the explosive in an incoming artillery shell and shoot it down, causing it to explode in midair—a feat previously thought to be impossible because artillery shells travel so fast. 

The US Navy plans to use its shipboard lasers to achieve a so-called "soft kill" on small boats, frying their outboard engines with laser power to leave them dead in the water. (And if that doesn't work, detonating their onboard ammunition.) Other soft ways to achieve a soft kill include destroying the engine of a car or truck, forcing it to stop, or precisely targeting sensors on ships and aircraft, blinding them to enemy attack.

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Lasers, not relying on actual physical bullets or shells, also have an "infinite magazine", their only limitation being the ability to generate power. Aircraft can use the power of a turboprop or jet engine to generate onboard electricity. Ships can use their engines to power high capacity electrical systems, and new classes of ships such as the USS Gerald R Ford class of aircraft carriers and the Zumwalt class stealth destroyers are built with powering lasers in mind. This also makes airplanes and ships safer in wartime, as there is no magazine of high explosive shells waiting to be struck by enemy fire and blow its host up.

For all their power, lasers do have drawbacks. Air molecules and particulates in it—things like water molecules, dust, and smoke particles—scatter and absorb laser light, resulting in a loss of power. An infra-red laser will lose half of its potency traveling 2.5 miles on a clear day, and in less than a mile on a hot, humid day. In other words, a 30 kilowatt beam at 100 feet might be a 15 kilowatt beam at 2.5 miles even under the best of conditions. The more powerful the laser, the more damage it can do at close range and the better it maintain a cohesive, damaging beam at long distances. 

All of this means that a laser loses strength every inch it travels. It also means that anyone who wants to avoid being struck by a laser would prefer less than ideal weather—fog, rain, or low-hanging clouds. Lasers could be degraded by starting smoky fires, or filling the air with tiny particles. 

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Another downside to lasers is that they generate tremendous amounts of heat, and must shed that heat between firings. Without a good cooling system, a laser will need to cool off between shots. This is less of a problem for ships, which can accommodate the bulk, or aircraft that can use air flow to cool the laser, but it could be a problem in ground vehicles and are a major barrier against handheld laser weapons. 

While particulates in the air are an active defense against lasers, a passive defense could be to armor the target with laser-deflecting mirrors or film with a mirror-like surface on it. Unlike conventional armor, which relies upon thick layers of steel or composites, shiny, mirror-like surfaces work much better against lasers. The less energy a target absorbs the better, and mirrored surfaces reflect laser energy, preventing it from being absorbed on the target surface. How much a mirrored surface absorbs depends on the type of laser: an infrared laser will have 96 percent of its energy reflected away, while more than half of an ultraviolet laser's energy will get through. 

The laser's shortcomings mean that, for now, lasers for now are limited to short-range, mostly defensive weapons. Lasers on fighters will most likely be used to shoot down incoming air-to-air missiles, or hit targets on the ground much like regular aircraft gun. Lasers on naval ships will be used for close-in defense against enemy missiles, aircraft and ships. Army lasers will likely be used to shoot down enemy missiles, aircraft, drones, artillery shells and rockets.

Lasers may never totally replace other weapons. An international agreement means they can't be used to target individual people, who must still be killed the old-fashioned way. Still, for targeting practically everything else, the time of lasers is finally coming. It's warfare at the speed of light. 

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