An airborne laser (ABL) is a

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...

system operated from a flying platform, as in the: * Soviet/Russian

Beriev A-60 The Beriev A-60 is a Soviet/Russian airborne laser laboratory aircraft based on the Ilyushin Il-76MD transport. In the 1970s a special aviation complex was established by the Soviets at Taganrog machine-building factory to develop airborne las ...

(1981, active) * American

Boeing YAL-1 The Boeing YAL-1 Airborne Laser Testbed (formerly Airborne Laser) weapons system was a megawatt-class chemical oxygen iodine laser (COIL) mounted inside a modified military Boeing 747-400F. It was primarily designed as a missile defense syste ...

(2002-2012, scrapped) * An American modified NKC-135A unit (1975-1984, in storage.)

Development

Development of airborne lasers in the United States began with the Airborne Laser Laboratory (ALL) developed at the USAF Weapons Lab (AFWL), now known as

Phillips Laboratory Phillips Laboratory was a research and development organization operated by the United States Air Force Materiel Command. In 1997, the Laboratory was merged into the Air Force Research Laboratory as the Space Vehicles and Directed Energy Director ...

, in the late 1970's and early 1980's. The ALL was based on a carbon dioxide

gas dynamic laser A gas dynamic laser (GDL) is a laser based on differences in relaxation velocities of molecular vibrational states. The lasing medium gas has such properties that an energetically lower vibrational state relaxes faster than a higher vibrational st ...

(GDL), operating at the

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

wavelength of 10.6 microns, and mounted on a modified Boeing KC-135 Stratotanker (

NC-135 The Boeing NC-135 and NKC-135 are special versions of the Boeing C-135 Stratolifter and Boeing KC-135 Stratotanker modified to operate on several different programs. Operational history Readiness Program In support of the U.S. Test Readiness P ...

). It was successfully tested, and in 1981 destroyed five

AIM-9 Sidewinder The AIM-9 Sidewinder (where "AIM" stands for "Air Intercept Missile") is a short-range air-to-air missile which entered service with the US Navy in 1956 and subsequently was adopted by the US Air Force in 1964. Since then the Sidewinder has prov ...

missiles and a simulated cruise missile (

BQM-34 The Ryan Firebee is a series of target drones developed by the Ryan Aeronautical, Ryan Aeronautical Company beginning in 1951. It was one of the first Jet engine, jet-propelled drones, and remains one of the most widely used target drones ever b ...

). Of note is that the ALL demonstrated one of the early uses of

deformable mirror Deformable mirrors (DM) are mirrors whose surface can be deformed, in order to achieve wavefront control and correction of optical aberrations. Deformable mirrors are used in combination with wavefront sensors and real-time control systems in ada ...

technology. To compensate for various atmospheric aberrations arising from turbulence and absorption of energy from the beam itself, it was necessary to modify the wavefront of the beam after it emerged from the laser resonator in order to ensure it would arrive at the target as a tightly focused spot. Subsequent to the

Gulf War The Gulf War was a 1990–1991 armed campaign waged by a 35-country military coalition in response to the Iraqi invasion of Kuwait. Spearheaded by the United States, the coalition's efforts against Iraq were carried out in two key phases: ...

, in 1996 the Airborne Laser (ABL) program was begun using a Chemical Oxygen Iodine Laser (COIL), also developed at AFWL in the 1970's and 1980's. The ABL was mounted on a modified Boeing 747. See

for fuller discussion.

Functionality

The original ALL, being a relatively long wavelength, sub-megawatt laser, killed its targets via two mechanisms. One was by direct illumination and heating of the guidance sensor of an air-to-air missile, which defeated its tracking system. The other was by heating a cruise missile or similar vehicle to the extent that the fuel tank exploded and destroyed the vehicle. Tracking used a

conical scanning Conical scanning is a system used in early radar units to improve their accuracy, as well as making it easier to steer the antenna properly to point at a target. Conical scanning is similar in concept to the earlier lobe switching concept used ...

technique, which employed the beam of the boresighted high-energy laser to acquire and track the target vehicle via its illuminated infrared return. The newer ABL had enough energy when fired to vaporize the metal of the missile that it was currently targeting. "It deposits enough heat to laze a hole through it. It's like taking a magnifying glass and burning a hole through a piece of paper, but we do it through metal," said Dr. Keith Truesdell, Phillips Lab chief of the applied laser technology branch. To help with firing, newer ABL systems utilize tracking lasers which have been tested recently in 2007 when the US Missile Defense Agency tested the track illuminator laser (TILL). The TILL is a solid state laser and is a key part of the fire control of the ABL system.

Issues

Operational costs of an airborne laser are quite high. The projected cost of the ABL program was listed as 5.1 billion USD in 2009 according to the US Department of Defense.

References

Military lasers {{mil-aviation-stub