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


Ad­vance Light He­li­copter Dhruv

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