Chemical oxygen iodine laser (COIL) is an infrared chemical laser that has been developed at the Air Force Research Laboratory in 1977, primarily for military applications. It outputs a beam of infrared at a wavelength of 1.315 µm. In continuous mode, the output power of the laser can be scaled up to megawatts.
The key properties of COIL include:
- Possibility of high power emission based on the chemical reaction
- Emission of high quality light with its low pressure gas laser medium
- Absorption of large amount of energy on the material due to its short wavelength
- Very low transmission loss in optical fibers.
The laser consists of an aqueous mixture of potassium hydroxide and hydrogen peroxide, molecular iodine and gaseous chlorine. When the aqueous peroxide solution is subjected to chemical reaction, it releases heat in addition to the production of potassium chloride molecules and excited oxygen known as singlet delta oxygen. Following this, excited oxygen gains a spontaneous lifetime of about 45 min, which in turn allows the singlet delta oxygen to transfer its energy to the iodine molecules that are incorporated to the gas stream. Further, the excited iodine undergoes stimulated emission in the optical resonating region of laser at 1.315 µm.
This laser is operated at very low gas pressures and rapid gas flow rate in order to eliminate heat from the lasing medium easily when compared to other high-power solid-state lasers. A halogen scrubber is employed to remove the traces of iodine and chlorine from the exhaust gas.
Although COIL was initially developed for military purposes, its properties make it useful for industrial processing applications also.
||Chemical reaction by combustion of singlet delta oxygen and iodine
COIL technology has gained importance over the past few years owing to its nearly diffraction-limited optical quality, high scalability and short, fiber-deliverable wavelength. These distinct characteristics have made COIL a suitable technology for nuclear warhead dismantlement and nuclear reactor decommissioning. It is used as a weapon laser for the advanced tactile laser programs and military airborne laser. In addition, COIL can also be used for commercial or industrial applications which demands noninvasive, precise and rapid drilling or cutting.
Other applications of COIL include:
- Paint stripping
- Rock crushing
- Dismantling of nuclear facilities
- Cleanup and survivor rescue during disaster
- High power fiber optic transmission.