1 Night Vision Technology 1. Introduction Nightvisiontechnology,bydefinition,literallyallowsonetoseeinthedark. Originallydevelopedformilitaryuse,ithasprovidedtheUnitedStateswitha strategic military advantage, the value of which can be measured in lives. Federal and state agencies now routinelyutilizethetechnologyforsitesecurity,surveillance aswellassearchand rescue.Nightvisionequipment hasevolvedfrombulky opticalinstrumentsinlightweightgogglesthroughtheadvancementofimage intensificationtechnology.Withthepropernight-visionequipment,youcanseea personstandingover200yards(183m)awayonamoonless,cloudynight!Night vision can work in two very different ways, depending on the technology used. 1.1ImageenhancementThisworksbycollectingthetinyamountsoflight, includingthelower portion oftheinfraredlight spectrum,that arepresentbutmay be imperceptible to our eyes, and amplifying it to the point that we can easily observe the image. 1.2Thermalimaging-This technologyoperates by capturing the upper portionof the Infraredlightspectrum,whichisemittedasheatbyobjectsinsteadofsimply reflected as light. Hotter objects, such as warm bodies, emit more ofthis lightthan cooler objects like trees or buildings. 1.3Types of Night Vision System Activesystems:Activesystemsuseaninfraredlightsourcebuiltintothecarto illuminate the road ahead with light that is invisible to humans.Passivesystems:Passivesystemsdonotuseaninfraredlightsource,insteadthey capture thermal radiation already emitted by the objects, using a thermo-graphic camera 2 2. The Basics Inordertounderstandnightvision,itisimportanttounderstandsomethingabout light. Theamountofenergyinalightwaveisrelatedtoitswavelength:Shorter wavelengths havehigherenergy.Ofvisiblelight,violethasthemostenergy,and red has the least. Just next to the visible light spectrum is the infrared spectrum. Infrared light can be split into three categories: Fig 1. Electromagnetic Spectrum Near-infrared(near-IR)-Closesttovisiblelight,near-IRhaswavelengthsthat range from 0.7 to 1.3 microns, or 700 billionths to 1,300 billionths of a meter. Mid-infrared(mid-IR)-Mid-IRhaswavelengthsrangingfrom1.3to3microns. Bothnear-IRandmid-IRareusedbyavarietyofelectronicdevices,including remote controls. Thermal-infrared(thermal-IR)-Occupyingthelargestpartoftheinfrared Spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30 microns. Thekeydifferencebetweenthermal-IRandtheothertwoisthatthermal-IRis emitted by an object instead of reflected off it. Infrared light is emitted by an object because of what is happening at the atomic level. Atoms areconstantlyinmotion.Theycontinuouslyvibrate,moveandrotate. Even theatomsthatmakeupthechairsthatwesitinaremovingaround.Solidsare actuallyinmotion!Atomscanbeindifferentstatesofexcitation.Inotherwords, they can have different energies. If we apply a lot of energy to an atom, it can leave what is calledtheground-stateenergylevelandmovetoanexcitedlevel.The levelof excitationdependsontheamountofenergyappliedtotheatomvia heat,lightor electricity. 3 Anatomconsistsofanucleus(containingtheprotonsandneutrons)andan electroncloud.Thinkoftheelectronsinthiscloudascirclingthenucleusin manydifferent orbits.In other words, if we apply some heat to an atom, we might expect that some of theelectronsinthelowerenergyorbitalswouldtransitionto higherenergyorbitals, moving farther from the nucleus Once an electron moves to a higher-energy orbit, it eventually wants to return tothe ground state. When it does, it releases its energy as aphoton -- a particle of light.Anexcitedelectronhasmoreenergythanarelaxedelectron,and justasthe electronabsorbedsomeamountofenergytoreachthisexcitedlevel,itcan release thisenergytoreturntothegroundstate.Thisemittedenergyisintheformof photons(lightenergy).Thephotonemittedhasaveryspecificwavelength(color) thatdependsonthestateoftheelectron'senergywhenthephotonisreleased. Anything that is alive uses energy, and so do many inanimate items such as engines and rockets. Energy consumption generates heat. In turn, heat causes the atoms in an object tofireoffphotonsinthethermal-infraredspectrum.Thehottertheobject, theshorter thewavelength oftheinfraredphotonitreleases.Anobjectthatisvery hotwilleven begintoemitphotonsinthevisiblespectrum,glowingredandthen moving up through orange,yellow,blueandeventuallywhite. 4 3. Thermal Imaging Here's how thermal imaging (Fig 2.) works: 1.A special lens focuses the infrared light emitted by all of the objects in view. 2.The focused light is scanned by a phased array of infrared-detector elements. The detectorelementscreateaverydetailedtemperaturepatterncalleda thermogram.It onlytakesaboutone-thirtiethofasecondforthedetector arraytoobtainthe temperatureinformationtomakethethermogram.This informationisobtainedfrom several thousand points in the field of view of the detector array. 3.Thethermogramcreatedbythedetectorelementsistranslatedintoelectric impulses. 4.The impulses are sent to a signal-processing unit, a circuit board with a dedicated chip that translates the information from the elements into data for the display. 5.Thesignal-processingunitsendstheinformationtothedisplay,whereitappears as various colors depending on the intensity of the infrared emission. The combination of all the impulses from all of the elements creates the image. Fig. 4--The basic components of a thermal-imaging system Fig 2- Thermal imaging 5 3.1 Types of Thermal Imaging Devices Mostthermal-imagingdevicesscanatarateof30timespersecond.Theycan sense temperaturesrangingfrom-4degreesFahrenheit(-20degreesCelsius)to 3,600F (2,000 C), and can normally detect changes in temperature of about 0.4 F (0.2 C). It is quite easy to see everything during theday......but at night, you can see very little. Thermal imaging lets you see again. Fig 3-- Thermal imaging at day and night

There are two common types of thermal-imaging devices: Un-cooled - This is the most common type of thermal-imaging device. The Infrared-detector elements are contained in a unit that operates at room temperature. This type of systemis completely quiet, activates immediatelyand has the battery built right in. Cryogenicallycooled-Moreexpensiveandmoresusceptibletodamagefrom rugged use, these systems have the elements sealed inside a container that cools them to below 32 F (zero C). The advantage of such a system is the incredible resolution and sensitivity that result from cooling the elements. Cryogenically-cooled systems can "see"a difference as smallas0.2F (0.1C) frommore than 1,000ft. (300m) away, which is enough to tell if a person is holding a gun at that distance! Whilethermalimagingisgreatfordetectingpeopleorworkinginnear-absolute darkness, most night-vision equipment uses image-enhancement technology. 6 4.Image Enhancement Image-enhancementtechnologyiswhatmostpeoplethinkofwhenyoutalkabout nightvision.Infact,image-enhancementsystemsarenormallycallednight-vision devices(NVDs).NVDsrelyonaspecialtube,calledanimage-intensifiertube (Fig. 4),to collect and amplify infrared and visible light. (Fig. 4)The image-intensifier tube changes photons to electrons and back again. Here's how image enhancement works: 1.Aconventionallens,calledtheobjectivelens,capturesambientlightandsome near-infrared light. 2. Thegatheredlightissenttotheimage-intensifiertube.InmostNVDs,the power supply for the image-intensifier tube receives power from two N-Cell or two "AA" batteries. The tube outputs a high voltage, about 5,000 volts, to the image-tube components. 3.Theimage-intensifiertubehasaphotocathode,whichisusedtoconvertthe photons of light energy into electrons. 4. Astheelectronspassthroughthetube,similarelectronsarereleasedfrom atomsinthetube,multiplyingtheoriginalnumberofelectronsbyafactorof thousands through the use of amicrochannel plate(MCP) in the tube. An MCP is a tinyglassdiscthathasmillionsofmicroscopicholes(microchannels)init, made usingfiber-optic technology.TheMCPiscontainedinavacuumandhas metal electrodesoneithersideofthedisc.Eachchannelisabout45timeslonger than it is wide, and it works as an electron multiplier. When the electrons from the photo cathode hit the first electrode of the MCP, they are 7 accelerated into the glass microchannels by the 5,000-V bursts being sent between the electrodepair.Aselectronspassthroughthemicrochannels,theycausethousands of otherelectronstobereleasedineachchannelusingaprocesscalledcascaded secondaryemission.Basically,theoriginalelectronscollidewiththesideofthe channel,excitingatomsandcausingotherelectronstobereleased.Thesenew electronsalsocollidewithotheratoms,creatingachainreactionthatresultsin thousands of electrons leaving the channel where only a few entered. An interesting factisthatthemicrochannelsintheMCParecreatedataslightangle(abouta5-degreeto8-degreebias)toencourageelectroncollisionsandreducebothionand direct-light feedback from the phosphors on the output side. 1.Attheendoftheimage-intensifiertube,theelectronshitascreencoatedwith phosphors.Theseelectronsmaintaintheirpositioninrelationtothechannelthey passed through, which provides a perfect image since the electrons stay in the same alignment as the original photons. The energy of the electrons causes the phosphors to reach an excited state and release photons. These phosphors create the green image onthescreenthathascometocharacterize night vision 2.Thegreenphosphorimageisviewedthroughanotherlens,calledtheocular lens, whichallowsyoutomagnifyandfocustheimage.TheNVDmaybeconnected to anelectronicdisplay,suchasamonitor,ortheimagemaybevieweddirectly through the ocular lens. 8 5.Active illumination Fig 5Night vision through Active illumination 1.Activeilluminationcouplesimagingintensificationtechnologywithanactive source of illumination in the near infrared (NIR) or shortwave infrared (SWIR) band. Examples of such technologies include low light cameras. 2. Active infrared night-vision combines infrared illumination of spectral range 7001,000nm(justbelowthevisiblespectrumofthehumaneye)withCCDcameras sensitivetothislight.Theresultingscene,whichisapparentlydarktoahuman observer, appears as a monochrome image on a normal display device. Because active infrared night-vision systems can incorporate illuminators that produce high levels of infraredlight,theresultingimagesare typicallyhigherresolution than othernight-visiontechnologies.Activeinfrarednightvisionisnowcommonlyfoundin commercial,residentialandgovernmentsecurityapplications,whereitenables effectivenighttimeimagingunderlow-lightconditions.However,sinceactive infrared light can be detected by night-vision goggles, there can be a risk of giving away position in tactical military operations. 9 3.Laser range gated imaging is another form of active night vision which utilizes a high powered pulsed light source for illumination and imaging. Range gating is a technique which controls the laser pulses in conjunction with the shutter speed of the camera's detectors. Gated imaging technology can be divided into single shot, wherethedetectorcapturestheimagefromasinglelightpulse,andmulti-shot, where the detector integrates the light pulses from multiple shots to form an image. Oneofthekeyadvantagesofthistechniqueistheabilitytoperformtarget recognition rather than mere detection, as is the case with thermal imaging. 6.Generations 6.1Generation0-Theearliest(1950's)nightvisionproductswerebasedonimage conversion, rather than intensification. They required a source of invisible infrared (IR) light mounted on or near the device to illuminate the target area. 6.2 Generation1-The"starlightscopes"ofthe1960's(VietnamEra)havethree image intensifiertubesconnectedinaseries.Thesesystemsarelargerandheavier thanGen2 andGen3.TheGen1imageisclearatthecenterbutmaybedistorted around the edges.Figure 6 illustrates first-generation night vision. Incominglightiscollimatedby fiber optic plates beforeimpacting aphotocathode which releases electrons,which in turn impactaphosphorscreen.Theexcitedscreenemitsgreenlightintoasecond fiber optic plate, and the process is repeated. The complete process is repeated three times providing an overall gain of 10,000. Fig. 6Generation 1 10 6.3 Generation 2 - The micro channel plate (MCP) electron multiplier prompted Gen 2 developmentin the 1970s.The"gain"providedbytheMCPeliminated the needforback-to-backtubes-therebyimprovingsizeandimagequality.The MCPenabled development of hand held and helmet mounted goggles. Second-generationimageintensification(fig.7)significantlyincreasedgainand resolutionbyemployingamicrochannelplate.Figure2depictsthebasic configuration. Themicrochannelplateiscomposedofseveralmillionmicroscopic hollowglasschannelsfusedintoadisk.Eachchannel,approximately0.0125mm in diameter, is coatedwith a special semiconductor which easily liberates electrons. A singleelectronenteringachannelinitiatesanavalancheprocessofsecondary emission, under influence of an applied voltage, freeing hundreds of electrons. These electrons, effectively collimated by the channel, increase the resolution of the device. With additional electron optics, details as fine as 0.025 mm can be realized (half the diameter of a human hair).

Fig 7- Generation 2 Currentimageintensifiersincorporatetheirpredecessor'sresolutionwith additionallightamplification.Themultialkaliphotocathodeisreplacedwitha galliumarsenidephotocathode;thisextendsthewavelengthsensitivityofthe detectorintothenearinfrared.Themoonandstarsprovidelightinthese wavelengths,whichbooststhe effectively availablelightby approximately 30%, bringing the total gain of the system to around 30,000. 6.4 Generation 3 - Two major advancements characterized development of Gen 3 in the late 1970s and early 1980s: the gallium arsenide (GaAs) photocathode and theion-barrierfilmontheMCP.TheGaAsphotocathodeenableddetectionof 11 objectsat greaterdistancesundermuchdarkerconditions.Theion-barrierfilm increasedthe operationallifeofthetubefrom2000hours(Gen2)to10,000 (Gen3),as demonstrated by actual testing and not extrapolation. 6.5Generation4-GEN-IIIOMNI-V-VIIdevicescandifferfromstandard Generation 3 in one or both of two important ways. First, an automatic gated power supplysystemregulatesthephotocathodevoltage,allowingtheNVDto instantaneouslyadapttochanginglightconditions.Thesecondisaremovedor greatly thinned ion barrier, which decreases the number of electrons that are usually rejected by the Standard GEN III MCP, hence resulting in less image noise and the ability to operate with a luminous sensitivity at 2,850 K of only 700, compared to operatingwithaluminoussensitivityofatleast1,800forGENIIIimage intensifiers. The disadvantage to a thin or removed ion barrier is the overall decrease in tube life from a theoretical 20,000 hrs.Mean time to failure (MTTF) for Gen III type, to 15,000 hrs. MTTF for GEN IV type. However, this is largely negated by the lownumberofimageintensifiertubesthatreach15,000hrs.ofoperationbefore replacement. While the consumer market classifies this type of system as Generation 4, the United States military describes these systems as Generation 3 Autogated tubes (GEN-III OMNI-VII).Moreover,asautogatingpowersuppliescannowbeaddedtoany previous generation of night vision, "autogating" capability does not automatically class the devices as a GEN-III OMNI-VII, as seen with the XD-4. Any postnominals appearingafteraGenerationtype(i.e.,GenII+,GenIII+)donotchangethe generationtypeofthedevice,butinsteadindicatesanadvancement(s)overthe original specification's requirements Auto-gating The ATG function was designed to improve the BSP feature to be faster and to keep thebestresolutionandcontrastatalltimes.ItisparticularlysuitableforAviators Night Vision goggles, operations in urban areas or for special operations. ATG is a unique feature that operates constantly, electronically reducing the duty cycle of the photocathode voltage by very rapidly switching the voltage on and off. This maintains 12 theoptimumperformanceoftheItube,continuouslyrevealingmissioncritical details, safeguarding the I tube from additional damage and protecting the user from temporary blindness. The benefits of ATG can easily be seen not only during day-night-day transitions, but also under dynamic lighting conditions when rapidly changing from low light to high light conditions (above 1 lx), such as sudden illumination of dark room. PHOTONIS ATG allows the tube to maintain as much as 90% of the nominal MTF and resolution of the high light level, whereas standard tubes without Auto-Gating would drop to 10-20 lp/mm, which is less than 25% of the nominal MTF and resolution of the high light level.AtypicaladvantageofATGisbestfeltwhenusingaweaponsightwhich experiences a flame burst during shooting (see figures below showing pictures taken at the impact zone of a dropped bomb). ATG would reduce the temporary blindness that a standard BSP tube would introduce, allowing them to continuouslymaintain eyes on target. ATGprovidesaddedsafetyforpilotswhenflyingatlowaltitudes,andespecially during takeoffs and landings. Pilots operating with night vision goggles are constantly subjected to dynamic light conditions when artificial light sources, such as from cities, interferewiththeirnavigationbyproducinglargehalosthatobstructtheirfieldof view.

Fig 8-Comparison between Different Generations 13 If you're using night vision to find a lost person in the woods, to locate boats or buoys onthewater,ortostargazeintothewilderness,youneedGeneration3 because it creates the best images when there is very little ambient light. Generation 2maybe the choice in situations with higher levels of ambient light. Fig 9 7.KEY GENERATION DEVELOPMENTS: GENERATION 1 (Developed in 1960's); Vacuum Tube Technology Full Moon Operation Amplification: 1,000 Operating Life: 2,000 HoursGENERATION 2 (Developed in 1970's); First Micro channel Plate (MCP) Application One-Quarter Moon Operation Amplification: 20,000 Operating Life: 2,500 HoursGENERATION 2+ (1970s)Development increased image tube bias voltage to improve gain. Additionally, a glass faceplate was added to improve resolution. 14 GENERATION 3 (Developed in 1990's); Improved MCP & Photocathode Starlight Operation Amplification: 40,000 Operating Life: 10,000 Hour GENERATION 3 Enhanced (2000's);ImprovementsinthephotocathodeandMCPresultedinincreasedgainand resolution. Fig 10 8. Characteristics of Night Vision Usingintensifiednightvisionisdifferentfromusingregularbinoculars and/or your own eyes. Below are some of the aspects of night vision that you shouldbeawareofwhenyouareusinganimageintensifiednightvision system. Textures, Light and Dark Objects that appear light during the day but have adull surface may appear darker, throughthenightvisionunit,thanobjectsthataredarkduringthe day but have a highlyreflectivesurface.Forexample,ashinydarkcolored jacketmayappear brighter than a light colored jacket with a dull surface. 15 Depth Perception Night vision does not present normal depth perception. Fog and Rain Nightvisionisveryresponsivetoreflectiveambientlight;therefore, thelight reflectingoffoffogorheavyraincausesmuchmorelighttogo towardthenight vision unit and may degrade its performance. Honeycomb Thisisafainthexagonalpatternwhichistheresultofthemanufacturing process. Black Spots A few black spots throughout the image area are also inherent characteristics ofall Night vision technology. Thesespots will remain constant and should notincreaseinsizeornumber.Seeexamplebelowofanimagewithblack spots. 9.Equipment and Applications Night-vision equipment can be split into three broad categories: 9.1Scopes-Normallyhandheldormountedonaweapon,scopesare monocular(oneeye-piece).Sincescopesarehandheld,notwornlike goggles, they are good for when you want to get a better look at a specific object and then return to normal viewing conditions. Fig 11- Scope 9.2Goggles-Aspecifictypeofnightvisiondevicethathasdual eyepiecesisthenightvisiongoggle(NVG).Gogglesdonothaveany 16 magnification and this allows you to use them while in motion mounted on your head, perfect for night gaming, orienteering, driving, safeguarding and searchandrescueapplications.WhenlookingtopurchaseaNVGoggles you need to check if they use one intensifier tube with the same image sent to both eyes, or a separate image intensifier tube for each eye. They often come with straps or Headgear to fit onto your head for use without hands. Similartothenightgogglesareonesthathasmagnificationlensesto magnify the image these are then referred to as night vision binoculars. Fig 12-GogglesFig 13- Binoculars 9.3Binoculars-Nightvisionbinocularsarebasicallynightvision goggles with magnification and so are electro-optical devices that amplify whatever existing light there is and send it onto your eyes. These should not be confused with the optical only night binoculars or night glasses. Whilst NVB'sdo possesssomemagnificationqualities,youshouldn'tdependon them for extreme distance viewing as most only have a magnification of 2x, there are however 3x and now 5x magnification night vision binoculars on themarket.Becauseofthemagnificationyoucannotusethemwhilstin motion and mounted on your head and so they often look more like normal binoculars. Their real function is to allow you to see a fair distance in dark orlowlightconditions.PopularmakesofnightbinocularsincludeATN, Luna Optics, Yukon and Bushnel.

17 Fig15-Camera Fig14 - Monocular 9.4CamerasCameraswithnight-visiontechnologycansendthe imagetoamonitorfordisplayortoaVCRforrecording.Whennight-vision capability is desired inapermanentlocation,suchasonabuilding oraspartoftheequipmentina helicopter, camerasareused. 10.Applications Common applications for night vision include: Military Law enforcement Hunting Wildlife observation Surveillance Security Navigation Hidden-object detectionEntertainment Before the introduction of image intensifiers, night glasses were the only method of night vision, and thus were widely utilized, especially at sea. Second World War era 18 nightglassesusuallyhadalensdiameterof56mmormorewithmagnification of seven or eight. Major drawbacks of night glasses are their large size and weight. Theoriginalpurposeofnightvisionwastolocateenemytargetsatnight.Itisstill usedextensivelybythemilitaryforthatpurpose,aswellasfornavigation, surveillanceandtargeting.Policeandsecurityoftenuseboththermal-imagingand Image-enhancementtechnology,particularlyforsurveillance.Huntersandnature enthusiasts use NVDs to maneuver through the woods at night. Detectives and private investigators use night vision to watch people they are assigned totrack.Manybusinesseshavepermanently-mountedcamerasequippedwithnight vision to monitor the surroundings. A specific type of NVD, the night vision goggle (NVG) is a night vision device with dual eyepieces. The device can utilize either one intensifier tube with the same image sent to both eyes, or a separate image intensifier tube for each eye. Night vision goggles combinedwithmagnificationlensesconstitutesnightvisionbinoculars.Othertypes include monocular night vision devices with only one eyepiece which may be mounted tofirearmsasnight sights.NVGandEVStechnologiesarebecomingmorepopular withhelicopteroperationstoimprovesafety.TheNTSBisconsideringEVSas recommended equipment for safety features A really amazing ability of thermal imaging is that it reveals whether an area has been disturbed-itcanshowthatthegroundhasbeenduguptoburysomething,evenif there is no obvious sign to the naked eye. Law enforcement has used this to discover itemsthathavebeenhiddenbycriminals,includingmoney,drugsandbodies.Also, recentchangestoareassuchaswallscanbeseenusingthermalimaging,which has provided important clues in several cases. A night vision device (NVD) is a device comprising an image intensifier tube in a rigid casing, commonly used by military forces. Lately, night vision technology has become more widely available for civilian use. For example, enhanced vision systems (EVS) have become available for aircraft to help pilots with situational awareness and avoid accidents.Thesesystemsareincludedinthelatestavionicspackagesfrom manufacturers such as Cirrus and Cessna. 19 A specific type of NVD, the night vision goggle (NVG) is a night vision device with dual eyepieces. The device can utilize either one intensifier tube with the same image sent to both eyes, or a separate image intensifier tube for each eye. Night vision goggles combinedwithmagnificationlensesconstitutesnightvisionbinoculars.Othertypes include monocular night vision devices with only one eyepiece which may be mounted tofirearmsasnight sights.NVGandEVStechnologiesarebecomingmorepopular withhelicopteroperationstoimprovesafety.TheNTSBisconsideringEVSas recommended equipment for safety features. Night glasses are single or binocular with a large diameter objective. Large lenses can gatherandconcentratelight,thusintensifyinglightwithpurelyopticalmeansand enabling the user to see better in the dark than with the naked eye alone. Often night glasses also have a fairly large exit pupil of 7 mm or more to let all gathered light into theuser'seye.However,manypeoplecannottakeadvantageofthisbecauseofthe limiteddilationofthehumanpupil.Toovercomethis,soldiersweresometimes issued atropine eye drops to dilate pupils. Nightvisionsystemscanalsobeinstalledinvehicles.Anautomotivenight vision system is used to improve a vehicle driver's perception and seeing distance in darknessorpoorweather.Suchsystemstypicallyuseinfrared cameras,sometimes combinedwithactiveilluminationtechniques,tocollectinformationthatisthen displayed to the driver. Such systems are currently offered as optional equipment on certain premium vehicles. 11.Night Vision Technology in Automobiles The streets of yesterday has turned to be monstrous night mare for the public with demon like vehicle that swift past the roads at very high speeds and the case gets worst in the night with drunken drivers ruling the road with high stake speeds. The reckless accidents that occur on roads during night times mainly owe to the poor visibility and make the drivers rather than driving ahead, predict their way ahead. 20 But this is not just the case of drunken drivers but also sensible drivers who find very bad visibility during the wee hours of morning or the odd evenings Thuscomestheuseofnightvisionsystemswhichusesinfra-redsensorsor headlights to provide a clear view of the road ahead and in the coming sections we shall discuss about the detailed working of the night vision systems in automobiles. HOW IS IT ASSOCIATED IN CAR 1. Night vision control unit 2. Controller display Fig 16- NVDs in cars 3. Controller 4. Instrument Cluster 5. Button in light switch Centre 6. Night vision camera 21 Working Of Night Vision Systems in Cars Automotive night vision comes into two flavors: near and far infrared (IR). The near infrared technology detects the portion of the IR band nearest to visible light. But, the near IR detector needs an assist. Special bulbs mounted next to the headlights are aimed straight ahead like a car's high beams,but they don't blind other drivers because the humaneyeisinsensitivetotheinfraredlight.TheNIRsystemisilluminatesthe surroundingswithinfraredlightinthewavelengthof800to900nm.Theinfrared reflection of objects is captured and converted to a digital signal by a Charge Coupled Device (CCD). The digital signal from the CCD is routed to the image processor that translates it into a format that can be viewed into a black and white head-up display beamed onto the wind-shield. The far infrared technology detects energy farther up the infrared band that is emitted by objects as heat. This far IR night vision is also called passive, because no special light source is required. The special camera these systems use- essentially a phased array of IR detector elements analogous to the pixels in an ordinary digital camera- createsatemperaturepatterncalledathermogram,whichisrefreshed30timesa second. The heat from a pedestrian or an animal is much greater than the heat coming to the camera from its surroundings. A signal processor translates the thermo gram data to an image suitable for display on a monitor. It has been found out that neither of the technologies has a clear advantage. But, not everyone thinks night vision in cars makes sense.Thebiggestproblemwithnightvisionisthatthesesystemsdemandthatthe driver take his/her focus from the road, which is not a good idea, and drivers will just increase their speed, believing themselves to be less at risk, so to avoid this problem the driver is given an automatic warning of the approaching object and thus he doesn't have to look every time on the monitor to check for vehicles and he can completely concentrateontheroadwhiledriving.Effectivealgorithmsarerequiredinorderto send a warning to the driver fast enough if a pedestrian is detected.22 Fig17Night Vision Technology used in Mercedes Benz Mercedes-Benz uses an active system or near-IR system that illuminates the night withprojectedinfraredlight,muchlikeopticsfoundinmilitary-issuenight-vision goggles Mercedes system uses NIR technology and produces an even, clear picture in the dark. This system is similar to night-vision goggles soldiers use. The NIR system intheMercedesilluminateseverythingasifitwereinthehighbeamsofthe vehicle.Byutilizingaseriesofprojectionbulbsandcameras,theMercedes' active night-vision system picks up the faintest traces of light and transforms it into a clear picture. The advantage is that the Mercedes system can see warmer living things just as clear as it can spot colder, dead animals or non-living objects.The drawback to the Mercedes system is its range: The system has a maximum effectiverangeoflessthan600feet(183meters).Anotherdrawbackisthe Mercedes' NIR system doesn't handle fog well, while the BMW's FIR system can see through the dense conditions. But unlike the BMW's system, the Mercedes monitor is located behind the steering wheel, directly in the driver's line of sight to the road, and the image quality is also crisper on the NIR system. Unlike night-vision optics used for military applications, BMW's system registers images based on body heat and produces images that resemble a photo negative.While that works well for deciphering between animals and people, it doesn't do muchforrevealingadeadanimalin the middle of theroadorperhapsa large rock or a fallen tree.23 BMW's infrared system uses sensors on the front of the car that pick up heat from objects and processes the thermal signature to display images on a quarter video graphics array (QVGA) display (320x240-pixel resolution) mounted on the dash in the center of the vehicle's console The BMW's system picks up the heat of the animal or pedestrian and displays it as a bright image. The warmer the target, the brighter the image displays. It has a range of around 980 feet (299 meters) and can pan in the direction the vehicle is heading. The FIR night vision system illuminates what's directly in front of the vehiclereasonablywell,butdoesn'toffertheclarityfoundintheMercedes system. ADVANTAGES 1. Improved vision conditions of dusk and darkness. 2. No dazzling by head lights of the oncoming vehicles. 3. Highlighting of illuminated, heat-emitting objects as pedestrian, cyclists, animals etc. helps safe driving. 4. Better overview of the driving situations. 5. The zoom functions of the object in the far distance at high speeds. 6. Illumination of the bends/curves (pivoting of image details) 7. Small compact size 8. Easy and comprehensive installation 9. Low maintenance 24 LIMITATIONS It is difficult to distinguish between objects in the foreground and the background of the image the entire image is continuously changing and because pedestrians vary in scale based on their distance to the viewer. The probability of true warnings (i.e. when the driver is about to hit the pedestrian) is low, as it often is in reality, then the odds of the true alarm, can be quite low even for very sensitive warning systems with very high hit rates and low false alarm rates 12.NVIS AIRCRAFT INTEGRATION Cockpit Lighting Aircraft Exterior Lighting Windshield/Window Transparency Physical ConstraintsHandling Qualities AFCS These are the areas that need to be considered when integrating NVG into an aircraft.For helicopters there is not usually a problem with windshield or window transmission ofinfra-redlight,butthisneedstobeconsidered.Thecockpitmaynotbelarge enough to allow pilot head movements with NVG, or there may be aircraft structure whichblocksacriticalportionofthepilotsFOV.Dependingonwhattypesof operation are contemplated, under which environmental conditions, and the aircrafts handling qualities, there may be a requirement to have increased AFCS automation, i.e. Rad Alt Height hold, Position hold. The complete loss of the NVG image is obviously hazardous, especially if it occurs at a critical point in the flight. The NVG incorporate a dual independent power pack, which warns the pilot of impending battery failure. BydesigntheNVGamplifylight,theydonotgenerateimagery.Therearesome image defects that could occur, but they do not generally resemble the real world, and 25 as such can be easily identified by the pilot. With proper training pilots learn to cope with the visual illusions possible with NVG.So hazardously misleading imagery is not a problem by design. Theaircraftlightingsystemmustbedesignedtomaketheilluminationofanon-compatible light extremely remote.The most reliable way to do this is to remove all incompatible light sources from the aircraft.If incompatible lights are retained they must be controlled using very reliableswitches that minimize inadvertent actuation by the pilot. 13.Future Night Vision Devices TheArmyispushingnight-visiontechnologiesintothedigitalrealm.Futurenight-vision goggles are being designed not just to see better at night but also to allow soldiers toshareimagesofwhattheyseewithothersoldierswhomaybemilesaway. Technologists agree that the goal is feasible, but contractors currently working on these next-generationgogglesareencounteringchallengesinmeetingtheArmys requirements for power, size and weight. Soldiers currently use traditional night-vision technology, called image intensification. Thesegogglesamplifynon-visibleparticlesoflighttoalevelofbrightnessthatthe humaneyecandetect.Theyalsoemployinfraredthermalsensors,whichsense temperaturedifferences.Warmeritemsappearbrighteronadisplay. Thefusionofbothtechnologieswouldresultin night-visiongogglesthatmergethe strengthsofimageintensificationaclear,sharpgreen-tintedpicturewiththe advantagesofinfraredtheabilitytoseepracticallyunderanyenvironmental condition.Greenisthecolorthatthehumaneyeseesmosteasily. The combination of the two systems into a single optical device resulted in what the Army calls an enhanced night vision goggle, or ENVG. 26 14.CONCLUSION In conclusion I believe that is wonderful how something originally designed for destruction, can now help people on an every-day basis.Todayinthe21stcenturywehavecomealongwayinthedevelopmentof night vision technology, from the early 1940s.In present scenario the applications of night vision technology is very essential to combat terrorism which is a major problem being faced by mankind. The innovation and implementation of night vision system has a great impact onautomotivesessionsuchassavingmanylivesfromdeathreducing accidents at night. NVDshaveprovedtobeextremelyversatileinthecurrentdayandhave brought maneuvering in combat, flight, and driving to a new level of safety and security. Where we once forged ahead blindly into the night, now both our armed forces and civilians alike are experiencing the ability of engineering to continue to bring light to the darkness and to exceed the physical limits of the human body. As new applications for NVDs continue to be found, research for this area thrives, pointing towards future advancements such as panoramic and color night vision goggles. We have much to look forward to in the field of night vision devices. 27 15. REFERENCES www.howstuffworks.com www.autoevolution.com/night vision works http://carl.sandiego.edu http://en.wikipedia.org/wiki/Night_vision Unknown author, Night Vision Devices. BookRags. 11/12/2008 Unknown author, Night Vision Goggles. GlobalSecurity. 11/10/2008