Britain has developed a laser-based weapon called DragonFire that can destroy or disable a UAV several kilometers distant. Each shot costs about $13 for the necessary electricity generated in the vehicle or ship carrying the DragonFire system. Britain is installing DragonFire in a 6x6 twelve-ton Wolfhound armored truck. DragonFire is also going to be installed on warships and replace conventional anti-aircraft or anti-missile systems.
Back in 2010 the U.S. Navy successfully tested a laser weapon, using it to destroy a UAV and then repeat that several times. The laser cannon was mounted on a KINETO Tracking Mount, which is similar, but larger and more accurate than the mount used by the Phalanx Close In Weapons System (CIWS). The navy laser weapon test used the radar and tracking system of the CIWS. In 2009 CIWS was upgraded so that its sensors could detect speedboats, small aircraft, and naval mines. Knocking down UAVs is not something that the navy currently needs help with, and the current laser gun technology has to be improved quite a bit before it's worth mounting on a ship.
This is a similar situation with laser weapons in the other services. In 2010 the U.S. Air Force fired its Airborne Laser Testbed (ALT) laser while in flight and hit a ballistic missile that had just been launched and was moving at 1,800 meters a second. The laser beam took several seconds to weaken the missile structure and cause it to come apart. This test came only eight months after an ATL was fired in flight for the first time. The target was some lumber on the ground, which was hit. The ATL weapon was carried in a C-130H four engine transport.
In 2005 manufacturers of combat lasers believed these weapons were only a few years away from battlefield use. To that end, Northrop-Grumman set up a new division to develop and build battle lasers. This optimism was caused by two successful tests in 2004. In one, a solid state laser shot down a mortar round. In another, a much more powerful chemical laser hit a missile type target. Neither of these tests led to any useable weapons, and the combat laser remained a weapon of the future. The basic problems are reliability and sufficient electrical power to generate the laser.
Solid state lasers have been around since the 1950s, and chemical lasers first appeared in the 1970s. The chemical laser has the advantage of using a chemical reaction to create the megawatt level of energy for a laser that can penetrate the body of a ballistic missile that is still rising in the air hundreds of kilometers away. The chemical reaction uses atomized liquid hydrogen peroxide and potassium hydroxide and chlorine gas to form an ionized form of oxygen known as singlet delta oxygen or SDO. This, in turn, is rapidly mixed with molecular iodine gas to form ionized iodine gas. At that point, the ionized iodine gas rapidly returns to its resting state, and while doing so releases photons pulsing at the right frequency to create the laser light. These photons are channeled by mirrors and sent on their way to the target which was being tracked and pinpointed by other lasers. The airborne laser weighed about six tons. It can be carried in a C-130H, producing a laser powerful enough to hit airborne or ground targets fifteen kilometers away. The laser exits via a targeting turret under the nose of the aircraft, and its beam is invisible to the human eye. The chemicals are mixed at high speeds, and the byproducts are harmless heat, potassium salt, water, and oxygen. A similar laser, flying in a larger aircraft like a B-747 freighter, would have enough range to knock down ballistic missiles as they take off. This is what was used in the recent test.
Nearly half a century of engineering work has produced thousands of improvements, and a few breakthroughs, in making lasers more powerful, accurate and lethal. More efficient energy storage has made it possible to use lighter, shorter range ground based lasers effective against smaller targets like mortar shells and short-range rockets. Northrop's move was an indication that the company felt confident enough to gamble its own money, instead of what they get for government research contracts, to produce useful laser weapons. A larger high energy airborne laser would not only be useful against ballistic missiles. Enemy aircraft and space satellites would also be at risk. But companies like Northrop and Boeing are still trying to produce ground and airborne lasers that can successfully operate under combat conditions. The big problem with anti-missile airborne lasers is the power supply. Lots of chemicals are needed to generate sufficient power for a laser that can reach out for hundreds of kilometers and do sufficient damage to a ballistic missile. To be effective, the airborne laser needs sufficient power to get off several shots. So far, no one has been able to produce such a weapon. That's why these lasers remain the weapon of the future until these fundamental problems are solved. DragonFire is a partial solution and now there will be more.