The ABL weapon system consists of a high-energy, chemical oxygen iodine laser (COIL) mounted on a modified 747-400F (freighter) aircraft to shoot down theater ballistic missiles in their boost phase. A crew of four, including pilot and copilot, would be required to operate the airborne laser, which would patrol in pairs at high altitude, about 40,000 feet, flying in orbits over friendly territory, scanning the horizon for the plumes of rising missiles. Capable of autonomous operation, the ABL would acquire and track missiles in the boost phase of flight, illuminating the missile with a tracking laser beam while computers measure the distance and calculate its course and direction. After acquiring and locking onto the target, a second laser - with weapons-class strength - would fire a three- to five-second burst from a turret located in the 747's nose, destroying the missiles over the launch area.

The airborne laser would fire a Chemical Oxygen Iodine Laser, or COIL, invented at Phillips Lab in 1977. The laser's fuel consists of the same chemicals found in hair bleach and Drano - hydrogen peroxide and potassium hydroxide - which are then combined with chlorine gas and water. The laser operates at an infrared wavelength of 1.315 microns, which is invisible to the eye. By recycling chemicals, building with plastics and using a unique cooling process, the COIL team was able to make the laser lighter and more efficient while - at the same time - increasing its power by 400 percent in five years. The flight-weighted ABL module would be similar in performance and power levels to the multi-hundred kilowatt class COIL Baseline Demonstration Laser (BDL-2) module demonstrated by TRW in August 1996. As its name implies, though, it would be lighter and more compact than the earlier version due to the integration of advanced aerospace materials into the design of critical hardware components. For the operational ABL system, several modules would be linked together in series to achieve ABL's required megawatt-class power level.

Atmospheric turbulence, which weakens and scatters the laser's beam, is produced by fluctuations in air temperature [the same phenomenon that causes stars to twinkle]. Adaptive optics rely on a deformable mirror, sometimes called a rubber mirror, to compensate for tilt and phase distortions in the atmosphere. The mirror has 341 actuators that change at a rate of about a 1,000 per second.

The Airborne Laser is a Major Defense Acquisition Program. After the Concept Design Phase is complete, the ABL will enter the Program Definition and Risk Reduction (PDRR) Phase. The objective of the PDRR phase is to develop a cost effective, flexible airborne high energy laser system which provides a credible deterrent and lethal defensive capabilities against boosting theater ballistic missiles.

The ABL PDRR Program is intended to show high confidence system performance scalable to Engineering and Manufacturing Development (EMD) levels. The PDRR Program includes the design, development, integration, and testing of an airborne high-energy laser weapon system.

In May 1994, two contracts were awarded to develop fully operational ABL weapon system concepts and then derive ABL PDRR Program concepts that are fully traceable and scaleable EMD. A single contract team was selected to proceed with the development of the chosen PDRR concept beginning in November 1996. Successful development and testing of the laser module is one of the critical 'exit criteria' that Team ABL must satisfy to pass the program's first 'authority-to-proceed' (ATP-1) milestone, scheduled for June 1998. Testing of the laser module is expected to be completed by April 1998. The PDRR detailed design, integration, and test will culminate in a lethality demonstration in the year 2002. A follow-on Engineering Manufacturing and Development/Production (EMD) effort could then begin in the early 2003 time frame. A fleet of fully operational EMD systems is intended to satisfy Air Combat Command's boost-phase Theater Air Defense requirements. If all goes as planned, a fleet of seven ABLs should be flying operational missions by 2008.

Performance requirements for the Airborne Laser Weapons System are established by the operational scenarios and support requirements defined by the user, Air Combat Command, and by measured target vulnerability characteristics provided by the Air Force lethality and vulnerability community centered at the Phillips Laboratory. The ABL PDRR Program is supported by a robust technology insertion and risk reduction program to provide early confidence that scaling to EMD performance is feasible. The technology and concept design efforts provide key answers to the PDRR design effort in the areas of lethality, atmospheric characterization, beam control, aircraft systems integration, and environmental concerns. These efforts are the source of necessary data applied to exit criteria ensuring higher and higher levels of confidence are progressively reached at key milestones of the PDRR development.

The key issues in the program will be effective range of the laser and systems integration of a Boeing 747 aircraft.

Airborne Laser Source