Night Vi­sion De­vices Es­sen­tial for Modern War­fare

The term night vi­sion de­vice (NVD) usu­ally refers to a com­plete unit, in­clud­ing an im­age in­ten­si­fier tube, a pro­tec­tive and gen­er­ally wa­ter-re­sis­tant hous­ing, and some type of mount­ing sys­tem

SP's LandForces - - FRONT PAGE - Lt Gen­eral V.K. Kapoor (Retd)

The term night vi­sion de­vice usu­ally refers to a com­plete unit, in­clud­ing an im­age in­ten­si­fier tube, a pro­tec­tive and gen­er­ally wa­ter-re­sis­tant hous­ing, and some type of mount­ing sys­tem.

NIGHT VI­SION IM­PLIES THE abil­ity to see at night. It is a vi­tal in­gre­di­ent of bat­tle­field trans­parency. The side that pos­sesses this ca­pa­bil­ity will have a dis­tinct ad­van­tage over their op­po­nents if the lat­ter are not sim­i­larly equipped. Hence this ca­pa­bil­ity is con­sid­ered an es­sen­tial in­gre­di­ent of modern war­fare and de­vel­op­ments in sci­ence and tech­nol­ogy have made it pos­si­ble to de­velop such de­vices which en­able hu­mans to see in the dark as well as un­der in­clement weather con­di­tions such as fog, rain, and snow, and even through smoke and dust. The side that can see bet­ter by night will have greater ad­van­tage on a bat­tle­field and other is­sues be­ing equal it may turn out to be a war-win­ning fac­tor. In ur­ban en­vi­ron­ment of counter-in­sur­gency and counter-ter­ror­ist op­er­a­tions its vi­tal im­por­tance for se­cu­rity forces in­volved can­not be down­played.

The term night vi­sion de­vice (NVD) usu­ally refers to a com­plete unit, in­clud­ing an im­age in­ten­si­fier tube, a pro­tec­tive and gen­er­ally wa­ter-re­sis­tant hous­ing, and some type of mount­ing sys­tem. Many NVDs also in­clude sacri­fi­cial lenses, IR il­lu­mi­na­tors and tele­scopic lenses. Re­search and de­vel­op­ment (R&D) is be­ing un­der­taken glob­ally to en­hance the reach, im­prove the res­o­lu­tion and re­duce the weight of night vi­sion de­vices in or­der to pro­vide a bet­ter edge to own side.

The In­dian Army too has hand-held NVDs on its in­ven­tory in var­i­ous cat­e­gories and quan­ti­ties al­beit equip­ping both in terms of quan­tity and qual­ity on its weapon sys­tems is still not sat­is­fac­tory. For ex­am­ple, its as­sault ri­fles are not fit­ted with night scopes. The con­cept and phi­los­o­phy for night vi­sion ac­ces­sories too needs re­fin­ing if we are to learn from the past mis­takes. For ex­am­ple, when the HHTIs were first im­ported from Is­rael and France only one charger per four HHTIs were pro­cured. This cre­ated ma­jor

prob­lems with widely dis­persed de­ploy­ments in J&K and forced the in­fantry to im­pro­vise charg­ers, which may have caused in­ad­ver­tent dam­age to the equip­ment. An­other ex­am­ple was of ar­tillery which went in for numer­ous laser tar­get des­ig­na­tors but only one charger that was kept cen­trally at the School of Ar­tillery and ev­ery time charg­ing was needed, in­di­vid­ual des­ig­na­tors had to be flown in and out. And there is no gain­say­ing that our De­fence Re­search and De­vel­op­ment Or­gan­i­sa­tion (DRDO) and pub­lic sec­tor un­der­tak­ings (PSUs) are way be­hind in the field of NVDs com­pared to their for­eign coun­ter­parts. Our night vi­sion prod­ucts are bulkier and with lesser res­o­lu­tion.

Types of NVD

Night vi­sion de­vices used for mil­i­tary pur­poses are of two types – Im­age In­ten­si­fiers and Ther­mal Im­agers. Both have their ad­van­tages and dis­ad­van­tages and ad­vent of new tech­nolo­gies is re­sult­ing in more so­phis­ti­ca­tion and bet­ter prod­ucts. Some ba­sic char­ac­ter­is­tics of both types of NVDs are given in suc­ceed­ing para­graphs.

Im­age In­ten­si­fiers: Night Vi­sion Gog­gles and Night Scopes

To­day, the most pop­u­lar and well-known method of per­form­ing night vi­sion is based on the use of im­age in­ten­si­fiers. Im­age in­ten­si­fiers are com­monly used in night vi­sion gog­gles and night scopes. More re­cently, on-chip gain mul­ti­pli­ca­tion CCD cam­eras have be­come pop­u­larised for per­form­ing low-light se­cu­rity, sur­veil­lance and as­tro­nom­i­cal ob­ser­va­tion.

The work­ing of the night vi­sion de­vice (im­age in­ten­si­fiers) in­volves the am­pli­fi­ca­tion of the avail­able light to achieve bet­ter vi­sion. 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). An ob­jec­tive lens fo­cuses avail­able light (pho­tons) on the pho­to­cath­ode of an im­age in­ten­si­fier. The light en­ergy causes elec­trons to be re­leased from the cath­ode which are ac­cel­er­ated by an elec­tric field to in­crease their speed (en­ergy level). These elec­trons en­ter holes in a mi­crochan­nel plate and bounce off the in­ter­nal spe­cially-coated walls which gen­er­ate more elec­trons as the elec­trons bounce through. This cre­ates a denser ‘cloud’ of elec­trons rep­re­sent­ing an in­ten­si­fied ver­sion of the orig­i­nal im­age.

The fi­nal stage of the im­age in­ten­si­fier in­volves elec­trons hit­ting a phos­phor screen. The en­ergy of the elec­trons makes the phos­phor glow. The vis­ual light shows the de­sired view to the user or to an at­tached pho­to­graphic cam­era or video de­vice. A green phos­phor is used in these ap­pli­ca­tions be­cause the hu­man eye can dif­fer­en­ti­ate more shades of green than any other colour, al­low­ing for greater dif­fer­en­ti­a­tion of ob­jects in the pic­ture.

All im­age in­ten­si­fiers oper­ate in the above fash­ion. Tech­no­log­i­cal dif­fer­ences over the past four to five decades have re­sulted in sub­stan­tial im­prove­ment to the per­for­mance of these de­vices. The dif­fer­ent par­a­digms of tech­nol­ogy have been com­monly iden­ti­fied by dis­tinct gen­er­a­tions of im­age in­ten­si­fiers. In­ten­si­fied cam­era sys­tems usu­ally in­cor­po­rate an im­age in­ten­si­fier to cre­ate a brighter im­age of the low-light scene which is then viewed by a tra­di­tional cam­era.

The ad­van­tages and dis­ad­van­tages of Im­age In­ten­si­fier de­vices are listed be­low.

Ad­van­tages

Ex­cel­lent low-light level sen­si­tiv­ity. En­hanced vis­i­ble imag­ing yields the best pos­si­ble recog­ni­tion and iden­ti­fi­ca­tion per­for­mance. High res­o­lu­tion. Low power and cost. Abil­ity to iden­tify peo­ple.

Dis­ad­van­tages

Since they are based on am­pli­fi­ca­tion meth­ods, some light is re­quired. This method is not use­ful when there is es­sen­tially no light. In­fe­rior day­time per­for­mance when com­pared to ther­mal im­agers. Pos­si­bil­ity of bloom­ing and dam­age when ob­serv­ing bright sources un­der low-light con­di­tions.

Ther­mal Imag­ing

Ther­mal imag­ing is a method of im­prov­ing vis­i­bil­ity of ob­jects in a dark en­vi­ron­ment by de­tect­ing the ob­jects’ in­frared ra­di­a­tion and cre­at­ing an im­age based on that in­for­ma­tion. Ther­mal imag­ing, near­in­frared il­lu­mi­na­tion, low-light imag­ing are the three most com­monly used night vi­sion tech­nolo­gies. Un­like the other two meth­ods, ther­mal imag­ing works in en­vi­ron­ments with­out any am­bi­ent light. Like near-in­frared il­lu­mi­na­tion, ther­mal imag­ing can pen­e­trate ob­scu­rants such as smoke, fog and haze.

The next ques­tion is how does ther­mal imag­ing work? An easy way to un­der­stand is that all ob­jects emit in­frared en­ergy (heat) as a func­tion of their tem­per­a­ture. The in­frared en­ergy emit­ted by an ob­ject is known as its heat sig­na­ture. In gen­eral, the hot­ter an ob­ject is, the more ra­di­a­tion it emits. A ther­mal imager (also known as a ther­mal cam­era) is es­sen­tially a heat sen­sor that is ca­pa­ble of de­tect­ing tiny dif­fer­ences in tem­per­a­ture. The de­vice col­lects the in­frared ra­di­a­tion from ob­jects in the scene and cre­ates an elec­tronic im­age based on in­for­ma­tion about the tem­per­a­ture dif­fer­ences. Be­cause ob­jects are rarely pre­cisely the same tem­per­a­ture as other ob­jects around them, a ther­mal cam­era can de­tect them and they will ap­pear as dis­tinct in a ther­mal im­age. Ther­mal im­ages are nor­mally grayscale in na­ture: black ob­jects are cold, white ob­jects are hot and the depth of gray in­di­cates vari­a­tions be­tween the two. Some ther­mal cam­eras, how­ever, add colour to im­ages to help users iden­tify ob­jects at dif­fer­ent tem­per­a­tures.

Un­cooled and Cryo­geni­cally Cooled De­vices

Ther­mal imag­ing de­vices are gen­er­ally ‘Un­cooled’ or ‘Cryo­geni­cally Cooled’. The un­cooled 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 the el­e­ments sealed in­side a con­tainer that cools them to be­low 0 de­gree Cel­sius. The ad­van­tage of such a sys­tem is the in­cred­i­ble res­o­lu­tion and sen­si­tiv­ity that re­sult from cool­ing the el­e­ments. Though more ex­pen­sive and more sus­cep­ti­ble to dam­age from rugged use, these sys­tems en­able a sol­dier to see whether a per­son is hold­ing a gun more than 300 me­tres away. Un­like tra­di­tional most night-vi­sion equip­ment which uses im­age en­hance­ment tech­nol­ogy, ther­mal imag­ing is great for de­tect­ing peo­ple or work­ing in near-ab­so­lute dark­ness with lit­tle or no am­bi­ent light.

Uses of Ther­mal Imag­ing

First de­vel­oped for mil­i­tary pur­poses, ther­mal imag­ing has since been adopted by law en­force­ment, fire and res­cue teams and se­cu­rity pro­fes­sion­als. For law en­force­ment and se­cu­rity staff, ther­mal imag­ing de­tects sus­pi­cious ac­tiv­ity over long dis­tances in to­tal dark­ness and through fog, smoke, dust, fo­liage, and many other ob­scu­rants. This al­lows of­fi­cers to ap­proach in stealth mode and make bet­ter in­formed de­ci­sions more quickly. Cam­eras may be hand-held, ve­hi­cle-mounted, tri­pod-mounted, or weapon-mounted. For se­cu­rity and sur­veil­lance sys­tems, ther­mal imag­ing cam­eras com­ple­ment CCTV cam­eras to pro­vide com­pre­hen­sive threat de­tec­tion and in­te­grate seam­lessly with larger net­works. For pre­dic­tive main­te­nance, ther­mal imag­ing re­veals ‘hot spots’ where fail­ure may be im­mi­nent in many elec­tri­cal and industrial fa­cil­i­ties and in­stal­la­tions.

Night Vi­sion De­vices — Gen­er­a­tions of Im­age In­ten­si­fiers

A night vi­sion de­vice can be ei­ther a first, se­cond, third or fourth-gen­er­a­tion unit. What this stands for is what type of im­age in­ten­si­fier tube is used for that par­tic­u­lar de­vice; the im­age in­ten­si­fier tube is the heart and soul of an NVD.

First-gen­er­a­tion is cur­rently the most pop­u­lar type of night vi­sion in the world. Util­is­ing the ba­sic prin­ci­ples de­scribed ear­lier, a first-gen­er­a­tion unit will am­plify the ex­ist­ing light sev­eral thou­sand times let­ting you clearly see in the dark. These units pro­vide a bright and sharp im­age at a low cost, which is per­fect, whether you are boat­ing, ob­serv­ing wildlife, or pro­vid­ing se­cu­rity for your home. You may no­tice the fol­low­ing when you are look­ing through a first-gen­er­a­tion unit. A slight high-pitched whine when the unit is on. The im­age you see may be slightly blurry around the edges. This is known as geo­met­ric dis­tor­tion. When you turn a first-gen­er­a­tion unit off it may glow green for some time. These are in­her­ent char­ac­ter­is­tics of a first-gen­er­a­tion unit which are nor­mal.

Se­cond-gen­er­a­tion is pri­mar­ily used by law en­force­ment or for pro­fes­sional ap­pli­ca­tions. This is be­cause the cost of a sec­ond­gen­er­a­tion unit is ap­prox­i­mately $500 to $1,000 more than a first-gen­er­a­tion unit. The main dif­fer­ence be­tween a first- and a se­cond-gen­er­a­tion unit is the ad­di­tion of a mi­cro-chan­nel plate, com­monly re­ferred to as a MCP. The MCP works as an elec­tron am­pli­fier and is placed di­rectly be­hind the pho­to­cath­ode. The MCP con­sists of mil­lions of short par­al­lel glass tubes. When the elec­trons pass through these short tubes, thou­sands more elec­trons are re­leased. This ex­tra process al­lows se­cond-gen­er­a­tion units to am­plify the light many more times than first-gen­er­a­tion giv­ing you a brighter and sharper im­age. There are var­i­ous cat­e­gories of up­grades in se­cond-gen­er­a­tion tubes. Each is an up­grade on the for­mer with slightly bet­ter res­o­lu­tion, bet­ter sig­nal to noise ra­tio and a longer tube life.

Third-gen­er­a­tion. By adding a sen­si­tive chem­i­cal, gal­lium ar­senide to the pho­to­cath­ode, a brighter and sharper im­age has been achieved over se­cond-gen­er­a­tion units. An ion bar­rier film was also added to in­crease tube life. Third-gen­er­a­tion pro­vides the user with good to ex­cel­lent low light per­for­mance. Sim­i­larly third-gen­er­a­tion de­vices have a num­ber of up­grades with bet­ter fea­tures.

Fourth-gen­er­a­tion. Gated/film­less tech­nol­ogy rep­re­sents the big­gest tech­no­log­i­cal break­through in im­age in­ten­si­fi­ca­tion of the past 10 years. By re­mov­ing the ion bar­rier film and ‘Gat­ing’ the fourth-gen­er­a­tion sys­tem demon­strates sub­stan­tial in­creases in tar­get de­tec­tion range and res- olu­tion, par­tic­u­larly at ex­tremely low light lev­els. This gen­er­a­tion of de­vices also has a num­ber of up­grades im­prov­ing the per­for­mance slightly with each up­grade. The use of film less tech­nol­ogy and auto-gated power sup­ply in fourth-gen­er­a­tion im­age in­ten­si­fiers re­sult in: Up to 100 per cent im­prove­ment in photo re­sponse. Su­perb per­for­mance in ex­tremely low light level (bet­ter S/N and EBI). At least triple high light level res­o­lu­tion (a min­i­mum of 36 lp/mm com­pared to 12 lp/mm).

Choice of NVDs

While choos­ing NVDs, three im­por­tant per­for­mance pa­ram­e­ters that need to be born in mind: Sig­nal-to-noise ra­tio (SNR) Res­o­lu­tion and mod­u­lar trans­fer func­tion (MTF) Life­time of the tube. Sig­nal-to-noise ra­tio is by far the most im­por­tant pa­ram­e­ter for an Im­age In­ten­si­fier. It is a mea­sure of the light sig­nal reach­ing the eye di­vided by the per­ceived noise as seen by the eye. The value of the SNR de­ter­mines the res­o­lu­tion at very low light-lev­els. There­fore, the higher the SNR the bet­ter the abil­ity to re­solve im­age de­tails un­der low light-level con­di­tions. The SNR is re­lated to the spe­cific de­sign of the tubes.

MTF is the max­i­mum line den­sity on a tar­get that can be re­solved by a hu­man eye and is ex­pressed in line pairs per mm (lp/ mm). A more ob­jec­tive per­for­mance in­di­ca­tor is given by the mod­u­la­tion trans­fer func­tion. High MTF val­ues at low spa­tial fre­quen­cies pro­vide sharp im­ages with a good con­trast.

Life­time of an Im­age In­ten­si­fier is an ex­tremely im­por­tant pa­ram­e­ter for night vi­sion ap­pli­ca­tions. A num­ber of dif­fer­ent def­i­ni­tions are used de­pend­ing on the man­u­fac­turer.

All Im­age In­ten­si­fier tubes pro­vide a green il­lu­mi­nated pic­ture and no night vi­sion tube is sim­i­lar to an­other. All tubes have dif­fer­ent cos­met­ics in terms of small spots or specs, pho­to­cath­ode colour­ing, or a chicken wire ef­fect from the mi­cro chan­nel plate. Most cos­met­ics are only no­ticed dur­ing view­ing in high light sit­u­a­tions such as view­ing with the day­light fil­ter on in a lit room. Most com­mer­cial and mil­i­tary sys­tems are thor­oughly tested by man­u­fac­tur­ers to en­sure re­li­a­bil­ity.

Mar­ket Trends

Ac­cord­ing to the an­a­lysts up­com­ing mar­ket trend that will pos­i­tively af­fect the growth prospects of the night vi­sion de­vices mar­ket is the aug­mented util­i­sa­tion of graphene. Graphene is an ul­tra-thin, ul­tra-light, ul­tra­strong, and ul­tra-flex­i­ble ma­te­rial that can be used in any prod­uct. The new graphenebased ther­mal sen­sor is just one atom thick, and it uses a cryo­genic cool­ing sys­tem to iden­tify heat pat­terns from a long dis­tance. The in­cor­po­ra­tion of graphene not only helps to re­duce the weight of night vi­sion de­vices but also helps to lower the price of the de­vice.

Prod­uct-based seg­men­ta­tion of the night vi­sion de­vices mar­ket is as un­der: Night vi­sion gog­gles Night vi­sion cam­eras Night vi­sion scopes The mar­ket re­search an­a­lysts have es­ti­mated the night vi­sion gog­gles prod­uct seg­ment to ac­count for ap­prox­i­mately 47 per cent of the to­tal mar­ket share by 2020. The ex­ten­sive use of night vi­sion gog­gles in the mil­i­tary and law en­force­ment seg­ments is a ma­jor fac­tor that will re­sult in the steady growth of this mar­ket seg­ment dur­ing the next four years. Ex­ten­sive mar­ket re­search car­ried out by the an­a­lysts has shown that the mil­i­tary mar­ket seg­ment will post an im­pres­sive mar­ket value of nearly $4 bil­lion by 2020.

The ex­ten­sive use of night vi­sion gog­gles in the mil­i­tary and law en­force­ment seg­ments is a ma­jor fac­tor that will re­sult in the steady growth of this mar­ket seg­ment dur­ing the next four years

US Army sol­diers agents as seen through a night vi­sion de­vice dur­ing an op­er­a­tion in Afghanistan

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