I'm sorry, where was your home planet again?
On Monday, April 8th, the U.S. Navy announced that it was moving ahead with mounting a ship-borne laser on a ship bound for deployment for the Gulf of Arabia. The new laser system, much lighter and cheaper than previous designs, is expected to give the ship, the USS Ponce, a cheap, effective weapon for downing drones and small attack boats, such as those favored by Iran. The Chief of Naval Operations Admiral Jonathan Greenert has stated that the weapon would be able to destroy or damage small drones at $1 worth of electricity.
Eventually, the Navy, and presumably other armed forces, want laser weapons to increase in power and efficiency to allow it to shoot down incoming missiles, aircraft, and larger targets. Current countermeasures either involved missiles, which cost hundreds of thousands of dollars per launch, or fast-firing defensive canons, which fire upwards of hundreds of rounds per second. Both are limited by the amount of ammunition carried as well as by the cost to operate.
Contrary to popular belief, lasers are not bullets made of light, in the vein of Star Trek or Star Wars. Lasers behave almost exactly the way one would logically expect a heat beam to behave, that is, invisibly and incredibly accurate. Because heat in the electromagnetic spectrum is invisible, the only warning of a laser attack is something catching fire nearby and maybe exploding.
The immediate benefits of replacing traditional kinetic weapons with lasers is a substantial improvement in range and accuracy, as gravity and wind do not affect light waves. A long term benefit is that ships will be carrying less weight, as shells and missiles are heavy and take up space.
Also, lasers are cool.
The navy laser is just the first project to be pushed towards field testing. The Army and Air Force also have their own prototype weapons, the former to shoot down artillery and mortar shells, the latter to mount of modified aircraft and provide a moving anti-ballistic missile system. The USS Ponce is expected to be redeployed in 2014.
