Laser weapon
A laser weapon[2] is a type of directed-energy weapon that uses lasers to inflict damage. Whether they will be deployed as practical, high-performance military weapons remains to be seen.[3][4] One of the major issues with laser weapons is atmospheric thermal blooming, which is still largely unsolved. This issue is exacerbated when there is fog, smoke, dust, rain, snow, smog, foam, or purposely dispersed obscurant chemicals present. In essence, a laser generates a beam of light that requires clear air or a vacuum to operate.[5]
For science-fiction guns, see Raygun. For guns used in sports competitions, see Laser pistol (sport).
Several types of laser have been identified as having the potential to be used as incapacitating non-lethal weapons. They can cause temporary or permanent vision loss when directed at the eyes. The extent, nature, and duration of visual impairment resulting from exposure to laser light depend on various factors, such as the laser's power, wavelength(s), collimation of the beam, orientation of the beam, and duration of exposure. Even lasers with a power output of less than one watt can cause immediate and permanent vision loss under certain conditions, making them potential non-lethal but incapacitating weapons. However, the use of such lasers is morally controversial due to the extreme handicap that laser-induced blindness represents. The Protocol on Blinding Laser Weapons bans the use of weapons designed to cause permanent blindness. Weapons designed to cause temporary blindness, known as dazzlers, are used by military and sometimes law enforcement organizations. Incidents of pilots being exposed to lasers while flying have prompted aviation authorities to implement special procedures to deal with such hazards.[6]
Laser weapons capable of directly damaging or destroying a target in combat are still in the experimental stage. The general idea of laser-beam weaponry is to hit a target with a train of brief pulses of light. The United States Navy has tested the very short-range (1 mile), 30-kW Laser Weapon System or LaWS to be used against targets like small UAVs, rocket-propelled grenades, and visible motorboat or helicopter engines.[7][8] It has been defined as "six welding lasers strapped together." A 60 kW system, HELIOS, is being developed for destroyer-class ships as of 2020.[9]
A dazzler is a directed-energy weapon intended to temporarily blind or disorient its target with intense directed radiation. Targets can include sensors or human vision. Dazzlers emit infrared or invisible light against various electronic sensors, and visible light against humans, when they are intended to cause no long-term damage to eyes. The emitters are usually lasers, making what is termed a laser dazzler. Most of the contemporary systems are man-portable, and operate in either the red (a laser diode) or green (a diode-pumped solid-state laser, DPSS) areas of the electromagnetic spectrum.
Initially developed for military use, non-military products are becoming available for use in law enforcement and security.[18][19]
The personnel halting and stimulation response rifle (PHASR) is a prototype non-lethal laser dazzler developed by the Air Force Research Laboratory's Directed Energy Directorate, U.S. Department of Defense.[20] Its purpose is to temporarily disorient and blind a target. Blinding laser weapons have been tested in the past, but were banned under the 1995 United Nations Protocol on Blinding Laser Weapons, which the United States acceded to on 21 January 2009.[21] The PHASR rifle, a low-intensity laser, is not prohibited under this regulation, as the blinding effect is intended to be temporary. It also uses a two-wavelength laser.[22] The PHASR was tested at Kirtland Air Force Base, part of the Air Force Research Laboratory Directed Energy Directorate in New Mexico.
Laser beams begin to cause plasma breakdown in the atmosphere at energy densities of around one megajoule per cubic centimeter. This effect, called "blooming," causes the laser to defocus and disperse energy into the surrounding air. Blooming can be more severe if there is fog, smoke, dust, rain, snow, smog, or foam in the air.
Techniques that may reduce these effects include:
Countermeasures[edit]
Essentially, a laser generates a beam of light which will be delayed or stopped by any opaque medium and perturbed by any translucent or less than perfectly transparent medium just like any other type of light. A simple, dense smoke screen can and will often block a laser beam. Infrared or multi-spectrum[89] smoke grenades or generators will also disturb or block infrared laser beams. Any opaque case, cowling, bodywork, fuselage, hull, wall, shield or armor will absorb at least the "first impact" of a laser weapon, so the beam must be sustained to achieve penetration.
The Chinese People's Liberation Army has invested in the development of specialized coatings that can deflect beams fired by U.S. military lasers. Laser light can be deflected, reflected, or absorbed by manipulating physical and chemical properties of materials. Artificial coatings can counter certain specific types of lasers, but a different type of laser may match the coating's absorption spectrum enough to transfer damaging amounts of energy. The coatings are made of several different substances, including low-cost metals, rare earths, carbon fiber, silver, and diamonds that have been processed to fine sheens and tailored against specific laser weapons. China is developing anti-laser defenses because protection against them is considered far cheaper than creating competing laser weapons.[90]
Dielectric mirrors, inexpensive ablative coatings, thermal transport delay, and obscurants are also being studied as countermeasures.[91] In not a few operational situations, even simple, passive countermeasures like rapid rotation (which spreads the heat and does not allow a fixed targeting point except in strictly frontal engagements), higher acceleration (which increases the distance and changes the angle quickly), or agile maneuvering during the terminal attack phase (which hampers the ability to target a vulnerable point, forces a constant re-aiming or tracking with close to zero lag, and allows for some cooling) can defeat or help to defeat non-highly pulsed, high-energy laser weapons.[92]