Chemical oxygen iodine laser
Encyclopedia
Chemical oxygen iodine laser, or COIL, is an infrared
chemical laser
. As the beam is infrared, it cannot be seen with the naked eye. It is capable of output power scaling up to megawatts in continuous mode. Its output wavelength
is 1.315 µm, the wavelength of transition of atomic iodine.
The laser is fed with gaseous chlorine
, molecular iodine
, and an aqueous mixture of hydrogen peroxide
and potassium hydroxide
. The aqueous peroxide solution undergoes chemical reaction
with chlorine, producing heat, potassium chloride
, and oxygen in excited state, singlet delta oxygen. Spontaneous transition of excited oxygen to the triplet sigma ground state is forbidden giving the excited oxygen a spontaneous lifetime of about 45 minutes. This allows the singlet delta oxygen
to transfer its energy to the iodine
molecules injected to the gas stream; they are nearly resonant with the singlet oxygen, so the energy transfer during the collision of the particles is rapid. The excited iodine then undergoes stimulated emission
and lases at 1.315 µm in the optical resonator region of the laser.
The laser operates at relatively low gas pressures, but the gas flow has to be nearing the speed of sound at the reaction time; even supersonic flow designs are described. The low pressure and fast flow make removal of heat from the lasing medium easy, in comparison with high-power solid-state lasers. The reaction products are potassium salt, water, and oxygen. Traces of chlorine and iodine are removed from the exhaust gases by a halogen scrubber.
COIL was developed by the US Air Force in 1977, for military purposes
. However, its properties make it useful for industrial processing as well; the beam is focusable and can be transferred by an optical fiber
, as its wavelength is not absorbed much by fused silica but is well absorbed by metals, making it suitable for laser cutting and drilling. Rapid cutting of stainless steel
and hastelloy
with a fiber-coupled COIL has been demonstrated. In 1996, TRW Incorporated
managed to get a continuous beam of hundreds of kilowatts of power that lasted for several seconds.
RADICL, Research Assessment, Device Improvement Chemical Laser, is a 20 kW COIL laser tested by the United States Air Force in around 1998.
COIL is the main weapon laser for the military airborne laser and advanced tactical laser
programs. On February 11, 2010, this weapon was successfully deployed to shoot down a missile
off the central California
coast in a test conducted with a laser aboard a Boeing
jumbo jet that took off from the Point Mugu Naval Warfare Center (for more details, see Boeing YAL-1
.)
All gas-phase iodine laser
(AGIL) is a similar construction using all-gas reagents, more suitable for aerospace applications.
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
chemical laser
Chemical laser
A chemical laser is a laser that obtains its energy from a chemical reaction. Chemical lasers can achieve continuous wave output with power reaching to megawatt levels...
. As the beam is infrared, it cannot be seen with the naked eye. It is capable of output power scaling up to megawatts in continuous mode. Its output wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
is 1.315 µm, the wavelength of transition of atomic iodine.
The laser is fed with gaseous chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
, molecular iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
, and an aqueous mixture of hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
and potassium hydroxide
Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...
. The aqueous peroxide solution undergoes chemical reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
with chlorine, producing heat, potassium chloride
Potassium chloride
The chemical compound potassium chloride is a metal halide salt composed of potassium and chlorine. In its pure state, it is odorless and has a white or colorless vitreous crystal appearance, with a crystal structure that cleaves easily in three directions. Potassium chloride crystals are...
, and oxygen in excited state, singlet delta oxygen. Spontaneous transition of excited oxygen to the triplet sigma ground state is forbidden giving the excited oxygen a spontaneous lifetime of about 45 minutes. This allows the singlet delta oxygen
Singlet oxygen
Singlet oxygen is the common name used for the diamagnetic form of molecular oxygen , which is less stable than the normal triplet oxygen. Because of its unusual properties, singlet oxygen can persist for over an hour at room temperature, depending on the environment...
to transfer its energy to the iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
molecules injected to the gas stream; they are nearly resonant with the singlet oxygen, so the energy transfer during the collision of the particles is rapid. The excited iodine then undergoes stimulated emission
Stimulated emission
In optics, stimulated emission is the process by which an atomic electron interacting with an electromagnetic wave of a certain frequency may drop to a lower energy level, transferring its energy to that field. A photon created in this manner has the same phase, frequency, polarization, and...
and lases at 1.315 µm in the optical resonator region of the laser.
The laser operates at relatively low gas pressures, but the gas flow has to be nearing the speed of sound at the reaction time; even supersonic flow designs are described. The low pressure and fast flow make removal of heat from the lasing medium easy, in comparison with high-power solid-state lasers. The reaction products are potassium salt, water, and oxygen. Traces of chlorine and iodine are removed from the exhaust gases by a halogen scrubber.
COIL was developed by the US Air Force in 1977, for military purposes
Boeing YAL-1
The Boeing YAL-1 Airborne Laser Testbed, weapons system is a megawatt-class chemical oxygen iodine laser mounted inside a modified Boeing 747-400F. It is primarily designed as a missile defense system to destroy tactical ballistic missiles , while in boost phase. The aircraft was designated...
. However, its properties make it useful for industrial processing as well; the beam is focusable and can be transferred by an optical fiber
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
, as its wavelength is not absorbed much by fused silica but is well absorbed by metals, making it suitable for laser cutting and drilling. Rapid cutting of stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
and hastelloy
Hastelloy
Hastelloy is the registered trademark name of Haynes International, Inc. The trademark is applied as the prefix name of a range of twenty two different highly corrosion-resistant metal alloys loosely grouped by the metallurgical industry under the material term “superalloys” or “high-performance...
with a fiber-coupled COIL has been demonstrated. In 1996, TRW Incorporated
TRW
TRW Inc. was an American corporation involved in a variety of businesses, mainly aerospace, automotive, and credit reporting. It was a pioneer in multiple fields including electronic components, integrated circuits, computers, software and systems engineering. TRW built many spacecraft,...
managed to get a continuous beam of hundreds of kilowatts of power that lasted for several seconds.
RADICL, Research Assessment, Device Improvement Chemical Laser, is a 20 kW COIL laser tested by the United States Air Force in around 1998.
COIL is the main weapon laser for the military airborne laser and advanced tactical laser
Advanced tactical laser
The Advanced Tactical Laser program is a US military program to mount a high energy laser weapon on an aircraft, initially the AC-130 gunship, for use against ground targets in urban or other areas where minimizing collateral damage is important. The laser will be a 100 kilowatt-class chemical...
programs. On February 11, 2010, this weapon was successfully deployed to shoot down a missile
Missile
Though a missile may be any thrown or launched object, it colloquially almost always refers to a self-propelled guided weapon system.-Etymology:The word missile comes from the Latin verb mittere, meaning "to send"...
off the central California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
coast in a test conducted with a laser aboard a Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
jumbo jet that took off from the Point Mugu Naval Warfare Center (for more details, see Boeing YAL-1
Boeing YAL-1
The Boeing YAL-1 Airborne Laser Testbed, weapons system is a megawatt-class chemical oxygen iodine laser mounted inside a modified Boeing 747-400F. It is primarily designed as a missile defense system to destroy tactical ballistic missiles , while in boost phase. The aircraft was designated...
.)
All gas-phase iodine laser
All gas-phase iodine laser
All gas-phase iodine laser is a chemical laser using gaseous iodine as a lasing medium. Like the chemical oxygen iodine laser , it operates at the 1.315 µm wavelength....
(AGIL) is a similar construction using all-gas reagents, more suitable for aerospace applications.