Night Vi­sion Tech­nolo­gies

Night vi­sion de­vices (NVDs) com­prise an im­age in­ten­si­fier tube, a pro­tec­tive hous­ing and a mount­ing sys­tem. Many NVDs also in­clude sac­ri­fi­cial lenses, in­frared il­lu­mi­na­tors and tele­scopic lenses. Night vi­sion gog­gles, night-scopes, night-monoc­u­lar, night

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Night vi­sion de­vices com­prise an im­age in­ten­si­fier tube, a pro­tec­tive hous­ing and a mount­ing sys­tem.

THE URGE FOR THE abil­ity to see by night went up in wartime but today con­flict sit­u­a­tions are an ev­ery­day af­fair. Night vi­sion de­vices ( NVDs) com­prise an im­age in­ten­si­fier tube (IIT), a pro­tec­tive hous­ing and a mount­ing sys­tem. Many NVDs also in­clude sac­ri­fi­cial lenses, in­frared (IR) il­lu­mi­na­tors and tele­scopic lenses. NVDs are be­ing used by the se­cu­rity sec­tor as well as civil­ians. Night vi­sion gog­gles (NVGs), night-scopes, night-monoc­u­lar, night weapon sights are vi­tal to any army. Longer reach and im­proved res­o­lu­tion pro­motes the chances of win­ning.

Types of NVD

NVDs are of two types: im­age in­ten­si­fiers (II) and ther­mal im­agers (TI). Im­age in­ten­si­fiers are more com­mon as their light am­pli­fi­ca­tion tech­nol­ogy uses the small amount of am­bi­ent light like moon, stars-light and con­verts this light en­ergy (pho­tons) into elec­tri­cal en­ergy (elec­trons). These elec­trons pass through a thin disk that’s about the size of a small coin and con­tains more than 10 mil­lion chan­nels. As the elec­trons go through the chan­nels, they strike the chan­nel walls, re­leas­ing thou­sands of more elec­trons. These mul­ti­plied elec­trons then bounce off of a phos­pho­rous screen which con­verts the elec­trons back into pho­tons, let­ting you see even when it’s pitch dark. To un­der­stand ther­mal imag­ing, it is im­por­tant to un­der­stand that IR can be split into three cat­e­gories; near IR (0.7 to 1.3 mi­crons wave­length), mid IR (1.3-3 mi­crons wave­length) and ther­mal IR (three mi­crons to over 30 mi­crons wave­length). The key dif­fer­ence be­tween ther­mal IR and the other two is that ther­mal IR is emit­ted by an ob­ject in­stead of re­flected off it. Most ther­mal imag­ing de­vices scan at a rate of 30 times per se­cond, sense tem­per­a­tures from -20 de­gree Cel­sius to 3,600 de­gree Cel­sius and can de­tect changes in tem­per­a­ture of about 0.2 de­gree Cel­sius. Ther­mal imag­ing de­vices are gen­er­ally ‘un-cooled’ or ‘cryo­geni­cally cooled’. The un-cooled ones are more com­mon wherein the IR de­tec­tor el­e­ments are con­tained in a unit that op­er­ates at room tem­per­a­ture. These de­vices are noise­less, ac­ti­vate im­me­di­ately and have in-built bat­ter­ies. Cryo­geni­cally cooled de­vices have el­e­ments sealed in­side a con­tainer that cools them to be­low zero de­gree Cel­sius. The ad­van­tage of such a sys­tem is the in­cred­i­ble res­o­lu­tion and sen­si­tiv­ity that re­sult from cool­ing the el­e­ments. These sys­tems en­able iden­ti­fy­ing whether a per­son is hold­ing a weapon more than 300 me­tres away. Ther­mal imag­ing can de­tect per­sons in near-ab­so­lute dark­ness with lit­tle or no am­bi­ent light.


NVDs are gen­er­ally clas­si­fied into four cat­e­gories al­beit with dif­fer­ing clas­si­fi­ca­tions— some clas­sify them as gen­er­a­tion zero, one, two, three and four (yet to be de­fined) while oth­ers clas­sify them as gen­er­a­tion one, two, three and four. Ad­vanced ver­sion of gen­er­a­tion three is also be­ing re­ferred to as gen­er­a­tion three ul­tra. Clas­si­fi­ca­tion of NVDs de­pends on what type of im­age in­ten­si­fier tube (IIT) is used in the par­tic­u­lar de­vice:

Zero-gen­er­a­tion: These were sniper scopes used in World War II, not re­ally IITs but im­age con­vert­ers re­quir­ing a source of in­vis­i­ble IR light mounted on or near the de­vice to il­lu­mi­nate the tar­get.

First-gen­er­a­tion: These were Starlight Scopes de­vel­oped in early 1960s. They pro­duced an im­age that was clear in the cen­tre of the field of view but suf­fered from large op­ti­cal dis­tor­tion around the pe­riph­ery.

Se­cond-gen­er­a­tion: De­vel­op­ment of the mi­cro chan­nel plate (MCP) in the late 1960s ush­ered the se­cond gen­er­a­tion NVDs which are high qual­ity with ex­cep­tional bright­ness and res­o­lu­tion. The MCP ac­cel­er­ated and mul­ti­plied elec­trons sub­sti­tut­ing cou­pling of three IIs of the first gen­er­a­tion.

Third-gen­er­a­tion: Fielded in the early 1980s, these de­vices saw two ma­jor tech­no­log­i­cal im­prove­ments; gal­lium ar­senide (GaAs) pho­to­cath­ode and ion bar­rier coat­ing to the MCP, pro­vid­ing com­bined in­crease in res­o­lu­tion, sig­nal to noise ra­tio and pho­to­sen­si­tiv­ity over tubes with a multi-al­kali pho­to­cath­ode—in­creas­ing sen­si­tiv­ity to light from the near-IR range of the spec­trum, greater de­tec­tion dis­tances, im­proved sys­tem per­for­mance un­der low-light con­di­tions and op­er­a­tional life in ex­cess of 10,000 hours com­pared to 2,0004,000 hours of se­cond gen­er­a­tion tubes.

Fourth-gen­er­a­tion: In 1998, gated film­less tech­nol­ogy was cre­ated by re­mov­ing the ion bar­rier film and gat­ing power sup­ply en­abling sub­stan­tial in­creases in tar­get de­tec­tion range and res­o­lu­tion. The film­less mi­cro chan­nel plate pro­vides a higher sig­nal-to-noise ra­tio than stan­dard third-gen­er­a­tion IITs re­sult­ing in bet­ter im­age qual­ity un­der low-light con­di­tions. Au­to­gated power sup­ply im­proves im­age res­o­lu­tion un­der high light con­di­tions and a re­duced halo effect that min­imises in­ter­fer­ence from bright light sources. The re­duced Halo max­imises the ef­fec­tive­ness of the NVD in dy­namic light­ing con­di­tions. How­ever, it was found that the same per­for­mance re­sults could also be achieved us­ing a third-gen­er­a­tion tube with a thin­ner ion bar­rier film and an auto-gated power sup­ply.

Sub­con­ti­nen­tal Scene

In­dian Army has on its in­ven­tory in var­i­ous cat­e­gories and quan­ti­ties of NVDs but ideal equip­ping both in terms of quan­tity and qual­ity is yet to be achieved. In 2008, me­dia had re­ported the lack of NVDs in In­dian Army par­tic­u­larly in the 3,000-strong tank fleet (only 10 per cent of tanks had night-fight­ing ca­pa­bil­ity) and soldiers faced glar­ing short­ages of NVDs, with NVDs in ser­vice a gen­er­a­tion be­hind what Pak­istan al­ready had; In­dian Army was hold­ing se­cond-gen­er­a­tion NVDs while Pak­istan had a range of third-gen­er­a­tion NVDs from the US un­der the War on Ter­ror Pact. Fi­nally in April 2013, The Min­istry of De­fence (MoD) ap­proved a ` 2,820 crore pro­posal to pro­vide NVDs to the In­dian Army; 5,000 ther­mal im­agers (TIs) will be pro­cured from the Bharat Elec­tron­ics Limited (BEL). Though Pak­istan con­tin­ues to re­ceive mod­ern NVDs from the United States to fight ter­ror­ism, its In­sti­tute of Op­tron­ics (IOP) also man­u­fac­tures NVDs for Pak­istan armed forces; crew served night vi­sion weapon sight (TVS-5A), in­di­vid­ual served night vi­sion weapon sight (PVS-4A), driver’s night vi­sion periscope (DNVP-1A) and avi­a­tor’s night vi­sion gog­gle. IOP’s fu­ture plans in­clude NVDs for ar­moured ve­hi­cles and he­li­copters. In­dia’s BEL is un­der­stood to have part­nered with Pho­to­nis af­ter con­sid­er­ing ex­tend­ing a re­la­tion­ship with ITT Ex­elis. ITT Ex­elis has set up of­fices to pur­sue the In­dian mar­ket post mem­o­ran­dum of un­der­stand­ing (MoU) signed with Tata at 2012 De­f­expo for man­u­fac­tur­ing sys­tems us­ing im­ported US tubes. Re­port­edly, Qiop­tiq’s Kite sight has been tri­aled with In­dia since 2009 with a po­ten­tial ac­qui­si­tion later this year with demon­stra­tions of the com­pany’s TI and II so­lu­tions hav­ing be­gun. Qiop­tiq also es­tab­lished a joint ven­ture with Rolta in 2009 to pur­sue op­por­tu­ni­ties in In­dia. Amer­ica Tech­nol­ogy Net­work (ATN) says it sold to In­dia MARS 4 and 6 TI weapon sights and the monoc­u­lar NVM-14 in 2011 for the Army. Sim­i­larly, Op­tix says they have sev­eral projects in In­dia, three of which are with the Navy in­clud­ing sales of the twin-tube Diana vari­ant NVG.

The Pho­to­nis Group is a global busi­ness serv­ing the photo-sen­sor tech­nol­ogy needs of world lead­ing

cus­tomers in the ar­eas of night vi­sion, in­dus­try and science and

med­i­cal imag­ing

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