Evading the laser
Laser warning system would eventually need to be fitted onto our armoured vehicles too in view of emerging threats from laser weapons albeit most of them are already fitted with smoke dispensing mechanism
The advent of laser weapons has added a new dimension to warfare. These have already been fitted and tried out from ground, sea and air platforms. Laser-fitted assault rifles are under development and their deployment in space as the ultimate weapon against nuclear ICBMs is well on the cards.
In the United States, the tactical high energy laser (THEL) has successfully shot down short- and medium-range tactical missiles and artillery rounds. However, one of the main challenges in understanding operational implications of laser weapons lies in the varied characteristics of different laser weapons. The most technologically advanced laser weapons are chemical lasers that derive their high power levels from chemical reaction that produce beams of intense infrared (IR) radiation. Electrically-powered solid state lasers (SSL) are less powerful, passing electricity through a crystal or glass medium to produce laser beams. SSL are being developed rapidly as they have the promise of tactical level employment.
Yet another category of lasers is the free electron lasers (FEL), using electricity to create laser light on different wavelengths to match changing environmental conditions. Capabilities that make lasers attractive for operational use are that they have a highly agile speed of delivery; rapid engagement of multiple targets and re-targeting can be effectively undertaken; high capacity magazine – number of shots is increased exponentially; low incremental cost per shot; accuracy and adjustability are of exceptional order; logistical support requirements are much lower, and the design is flexible.
At the same time there are also factors that limit the operational employment of laser weapons, these being: atmospheric attenuation and turbulence; line of sight dependency; minimal effects on hardened structures and armoured vehicles; single wavelength limits the range of operational conditions in which these are effective; eye safety needs to be catered for, and; chemical fuels and exhaust.
Considering the strengths and limitations of laser weapons, they are well suited for active defence as well as offensive strikes. As part of active defence, they can provide air, land, sea and space platforms the ability to defend themselves. Similarly, other plat-
forms and large areas can also be protected from missiles, aircraft, bombs, artillery shells and rocket attacks. In offensive strike role, laser weapons provide the capability to achieve lethal or non-lethal effects against a whole range of suitable targets.
The proliferation of laser weapons has increased the calls for countermeasures. Because lasers are basically light, phenomenon can be significantly decreased or negated altogether by phenomenon like fog, rain, smoke, which can disperse or refract the laser beam to ineffectualness depending on how thick the beam is. If the target surfaces are reflective, they also are an obstacle to some limited extent bouncing the beam but reflective surfaces are not enough by themselves against laser attack since mirrors are usually frequency specific, making them vulnerable to a laser weapon that can easily change the beam wavelength. Yet, mirrors will absorb some amount of energy of the laser beam, causing melting or distortion of the mirror surface.
However, unless the mirror is unusually tough and smooth down to its component molecules, it won’t be able to reflect a laser hit in the same spot more than once or twice. Yet, if the object has the same colour as the laser beam, it can neutralise the laser; even a blanket with the ‘same’ colour can therefore deflect or degrade the laser beam of matching colour. The fallout is that either the laser beam should be tunable or at least produce a laser beam that is not common. On balance, reflective surfaces and same colour pigments would be of doubtful value against laser weapons with changeable frequencies. Also, having a highly reflective or bright surface easily detected by adversary’s sensors would be a profound disadvantage that may significantly outweigh any protection provided.
Another effective defence against laser weapons is through use of aerosols for protection through dispensers. These are usually available in the form of a canister or a bomb, as also cans or casings that can spray the aerosol speedily. The aerosol pumps ultrafine reflective particles into the air for protection against a potential target. These ultrafine particles remain suspended in the air for considerable time. The laser beam hitting the aerosol disperses once it hits the aerosol provided both the beam and the aerosol have matching wavelengths.
Mechanised forces are also going in for the use of ‘Ablative Armour’. This is generally made of an array of tightly clustered gel or foam packs. When the laser beam hits one of these foam packs, the heat of the beam boils the foam/gel and the explosive reaction absorbs, deflects or disperses the energy of the beam. However, a second laser beam fired at the same spot will go through and through. Considerable research is ongoing in the development of ‘superconductive energy dispersive armour’; fabric interwoven with superconductor wire to instantly absorb the incoming electromagnetic energy beam and disperse it evenly over its entire surface area. Of course, it depends on the development of room temperature superconductors. To counter the superconductive energy dispersive armour, the laser beam would have to pump in enough energy to fully destroy the entire armour together before it can penetrate through to reach its intended target. This will be even more complex if the superconductor mesh protecting the armour is cooled through the refrigeration unit or a heat sink. In such eventuality, even more energy would be required to overcome the superconductor mesh and penetrate through to the target effectively.
Proliferation of laser weapons have forced most armies to go in for laser warning systems for their aircraft, helicopters, tanks and armoured vehicles. Certain versions of India’s advance light helicopter (ALH) too has such system, from Saab in instant case; land electronic defence system (LEDS) – 50 Mk II, which is an integrated, modular, active defence system consisting of a laser warning system (LWS) and an on-board smoke controlling system (OSCS).
The LWS Control offers: capability to integrate to the host platforms of battlefield management system (BMS capability to integrate to an external on-board smoke control unit to fire the on-board smoke grenades manually or automatically once threat is detected; capability to integrate to and cue an external remote weapon system (RWS) in direction of the threat detected, and; capability to integrate to and cue a blinding laser in the direction of the detected threat.
Features of the LWS include: full hemispherical coverage; detecting and managing all known lasers associated with anti-armour threats; simultaneously dealing with up to eight threats; full range threat management option including classification, identification and library linked prioritisation; provision of threat positional data in azimuth and elevation; low false alarm rate; stand alone or integrated mode of operation; redundancy because of multiple sensors; unique anti-reflection capability that is extremely efficient in typical high clutter land scenarios; auditory threat alerts on intercom; user definable threat library tools; built in test capability, and; laser training system compatibility.
The OSCS control offers: the capability to integrate to host platforms of BMS, turret position indicator (TPI), GPS, MET Sensor and RWS; capability to integrate to an external sensor suite (like laser warning, radar, acoustics) that provides threat direction inputs, and; capability to integrate to on-board smoke tubes that are installed on a platform, turret, RWS, or any combination thereof. Features of the OSCS include: full hemispherical coverage; independent of smoke supplier and calibre; smoke tube inventory management; automatic or manual firing; optimal automatic dispensing of 120 degrees around threat bearing; misfire management; hatch open management; built in test capability; communication channel configurability to suite platform integration; integration to any sensor suite, and; ballistic control platform configurable (availability of wind speed, turret and RWS rotation).
Laser warning system would eventually need to be fitted onto our armoured vehicles too in view of emerging threats from laser weapons albeit most of them are already fitted with smoke dispensing mechanism. Due thought also needs to be given to likely future targets for laser attack who presently are not configured to create their own smoke screens. These would be missile launchers, missile sites, command and control vehicles especially in manoeuvre battle, and even artillery guns. SP
Tactical high energy laser / Advanced concept technology demonstrator
LT GENERAL (RETD) P.C. KATOCH
Advance Light Helicopter Dhruv