The U.S. Navy believes it has found a laser technology that is capable of being useful in combat. This is not a sudden development but has been going on for most of the last decade. Three years ago the navy successfully tested this new laser weapon (six solid state lasers acting in unison), using it to destroy a small UAV. That was the seventh time the navy laser had destroyed a UAV this way. But the LaWS (Laser Weapon System) was not yet powerful enough to do this at the range, and power level, required to cripple the expected targets (missiles and small boats). The manufacturer convinced the navy that it was just a matter of tweaking the technology to get the needed effectiveness. Three years later another test was run, under more realistic conditions. LaWS worked, knocking down a larger UAV at longer range. The navy now plans to install the system in a warship within the year for even more realistic testing.
The LaWS laser cannon was mounted on a KINETO Tracking Mount, which is similar, but larger (and more accurate), than the mount used by the Phalanx CIWS (Close In Weapons System). The navy laser weapon tests used the radar and tracking system of the CIWS. Four years ago CIWS was upgraded so that its sensors could detect speedboats, small aircraft, and naval mines. This was crucial because knocking down UAVs is not something that the navy needs help with. But with the ability to do enough damage to disable boats or missiles that are over two kilometers distant meant the LaWS was worth mounting on a warship. LaWS may yet prove incapable of working under combat conditions, but so far this new development has kept passing tests.
Such was not the case with an earlier research effort using chemical lasers. Two years ago the U.S. Department of Defense halted work on the U.S. Air Force ALT (Airborne Laser Testbed). The project was put into storage until such time as more effective technology is available to revive the effort, or it is decided that the ALT is not worth the storage expense. ALT cost over $5 billion during its 16 years of development. It never worked, at least not in a practical sense. Three years ago, for the second time in a row, the ALT failed in an attempt to use its laser to destroy a ballistic missile. That time, the problem was with the radar and fire control system, which failed to lock the laser onto the actual missile (although the radar did detect the actual missile launch). In the past the main problem has been a lack of power to drive the laser to lethal levels. Because of that, the ALT program has been an expensive near miss for nearly two decades. Four years ago ALT was demoted from a system in development to a research program. The reason for this was all about energy supply. Even if ALT worked flawlessly it did not have enough energy to hit a launching missile from a safe (from enemy fire) distance. ALT needed more than twenty times as much energy than it had and it was believed it would be a while before that problem was solved.
A decade ago developers of combat lasers were more optimistic. Eight years ago 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 generated by two successful tests nine years ago. 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 remains the "weapon of the future." The basic problems are reliability and ammo (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 (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 is being tracked and pinpointed by other lasers). The airborne laser weighs 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. The laser 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 (B-747 based ALT) was supposed to have enough range to knock down ballistic missiles as they took off. But the ALT never developed sufficient range to be an effective weapon.
The LaWS uses electricity, and more and more U.S. warships are producing a lot of electricity, mainly because it is used to operate electrical motors to propel the ship and, as part of that plan, operate weapons like LaWS. Thus a warship with an electrical drive (propulsion) system would be able support multiple shots from LaWS at low cost (a few dollars per firing). By current standards that’s pretty inexpensive ammo. The 20mm shells for the Phalanx cost less than $30 each but you have to fire a hundred or more at each target. The 20mm cannon is being replaced by RIM-116 "Rolling Air Frame" missiles that have a longer range (7.5 kilometers) than the 20mm cannon (two kilometers) but cost nearly half a million dollars each.
Nearly half a century of engineering work has produced thousands of improvements, and a few breakthroughs, in making the 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 a decade ago 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 but 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 has always been the power supply. A lot 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. Shorter range solid state lasers need lots of electricity. This is difficult for aircraft or ground troops but not for properly equipped ships. That's why these lasers remain "the weapon of the future" and will probably remain so for a while.
LaWS takes a different approach, using existing solid-state laser technology tweaked to complement the 20mm cannon shells normally used with Phalanx. Unlike the 20mm autocannon, the power of LaWS can be adjusted down to non-lethal (but blinding to the human eye) levels. That makes LaWS more flexible than the 20mm cannon and cheaper to operate. That will happen if LaWS proves able to operate under the same conditions that the 20mm cannon in Phalanx has operated for decades.