CONTENTIntroductionTypes of night vision- Biological night vision- Technical night visionNight vision devicesAdvantageDisadvantageApplicationConclusionReference
Night vision technology allows one to see inthe dark INTRODUCTION It is originally developed for the military use. In other word we say that Night vision technology is atype of image processing where we get to see Imagesin the dark With the proper night vision equipment we can see aperson standing over 200 yards (183 metres)away ona moonless cloudy night.
Night vision approachesThere are two types of night vision approaches1) Spectral range-Enhanced spectral range allows the viewerto take advantage of non-visible sources ofelectromagnetic radiation (such as near-infrared or ultraviolet radiation). Someanimals can see well into the infrared orultraviolet compared to humans.2)Intensity range:It is the ability to see with very small quantitiesof light. Many animals have better nightvision than humans . To enhanced intensityrange in achieved via technological meansthrough the use of an image intensifier , gainmultiplication devices and photo detectors.
TYPES OF NIGHT VISION1. Biological Night Vision2. Technical Night Vision(A) Image Intensification(B) Thermal Imaging
BIOLOGICAL NIGHT VISIONTECHNOLOGYSome animal like cat , owl and deep sea animals can see innight because they have a tissue layer called the tapetumlucidum, in the back of the eye that reflect light back throughthe retina .But human has lack of this layer , hence human can not seein night .Hence a chemical called RHODOPOSIN that allows nightvision .Molecule of rhodoposin in the rods of eye undergoes achange in shape as they absorb light.Rhodoposin is extremely sensitive to light .Hence human can see in night for few hour with the help ofrhodoposin
WORKING OF TECHNICAL NIGHTVISION(A) IMAGE INTESIFICATIONThis method of night vision amplifies the available light toachieve better vision.A conventional lens, captures ambient light.
The light energy causes electrons to be released from thephotocathode plate.These electrons enter a micro channel plate and generatemore electronsThese electrons hit a phosphor screen and maintain theirposition through the channel.The green phosphor image is viewed through another lenscalled ocular lens, which allows you to magnify and focusthe image.
(B) THERMAL IMAGINGThis method do not require any ambient light at all.principal -: All objects emit infrared energy as a functionof their temperature. This technology operates bycapturing the upper portion of infra red light spectrumA special lens focuses the infrared light emitted by all of theobjects in view.The focused light is scanned and create temperaturepattern called THERMOGRAM.The pattern created is translated into electric impulsesThe impulses are sent to a circuit board that translates theinformation into data for the display. signal-processing unit sends the information to the display.
NIGHT VISION DEVICESNight vision devices arebasically divided into threecategories Scopes: They are monocularnormally handheld ormounted on a weapon.Goggles: They are binocularand worn on the head.Cameras: Used fortransmission or recording ofimages mostly if the locationis fixed.
GENERATIONSGENERATION 0 Night vision devices were based on image conversion rather than onimage intensification. The first night vision device the "sniperscope" or"snooperscope", were introduced by the US Army in World War IIGENERATION 1 Focused on the ability to see without additional light. NVD began using intensified natural lighting. Military scientists created two – stage cascade image tube.
GENERATION 2There were two major development in NVD technology , first wasthe micro channel plate and other was in thermal imaging.The images are less distorted and brighterGENERATION 3Longer life and more defined images.It maintains the MCP from GEN 2 and also it has photocathode plate.Better resolution and sensitivity.GENERATION 4Known as “filmless and gated” technology.improvement in high- and low-level light environmentsReduced background noise
ADVANTAGEHigh SensitivityLow power RequirementAble to see in darkLight WeightSmall in size
DISADVANTAGEImage is not good quality with NVT.Image is not look its original place i.efarer image is look nearer.Loose normal eye vision if it use regularly
APPLICATIONMilitaryIn vehicle during winter and foggy dayHunting and wildlife ObservationSecurityNavigation
CONCLUSIONNight vision technology has some limitationsbut it is very useful technology in securitypurpose and wildlife. Improving this technologyto reduce limitations it can use in future formilitary and another purpose because now aday terrorism is big problem for any country.Hence this technology is helpful in war againstterrorism