Boeing's high-tech YAL-1 Airborne Laser (ABL) weapons system consists of a high energy laser, flight turret assembly, tracker Illuminator lasers, and a beacon illuminator -- to be installed on modified 747-400Fs. Simply put, it first uses infrared sensors to detect missiles, then three low power tracking lasers calculate speed/aimport, and lastly, the main laser is fired for 3-5 seconds from a front-mounted turret. Video after the break. Click here for more pictures.
[sources/credit 1 | 2]