What is night vision History Working of night vision device Generations Usage References
The word ‘Night vision’ itself means theability to see in low light conditions. Humans have poor night vision compared tomany other animals.
So we all might have a question in our mind that is thisreally possible to see in the dark night? The answer is……..YES, we can see in the dark nightusing the proper equipment made by using thistechnology. We can see a person standing over 183m(200 yards)away in the dark night.
Pre 1940’s: Flares and spotlights were used foroperations at night. Due to the nature of these early night vision devices(NVD), they gave away tactical positions. Military scientists began to think of ways to improvenight vision to gain a strategic advantage
The night vision is possible because of twoapproaches:(1) Sufficient spectral range(2) Sufficient intensity range. Two technologies are used for night vision:(1)Thermal Imaging(2)Image Intensification
Infrared light is used to visualize the things in the dark. The amount of energy in a light wave is related to itswavelength: Shorter wavelengths have higher energy. Of visible light, violet has the most energy, and red has theleast. Just next to the visible light spectrum is the infraredspectrum.
1.A special lens focuses the infrared light emitted byall of the objects in view.2.The focused light is scanned by a phased array ofinfrared-detector elements. The detector elementscreate a very detailed temperature pattern called athermogram. It only takes about one-thirtieth of asecond for the detector array to obtain thetemperature information to make the thermogram.3.The thermogram created by the detector elementsis translated into electric impulses.4.The impulses are sent to a signal-processing unit,a circuit board with a dedicated chip that translatesthe information from the elements into data for thedisplay.5.The signal-processing unit sends the informationto the display, where it appears as various colorsdepending on the intensity of the infraredemission.6.The combination of all the impulses from all ofthe elements creates the image.
NVDs have been around for more than 50years. They are categorized by generation. Each substantial change in NVD technologyestablishes a new generation.
Created by US Army. Uses active infrared. A projection unit called IR illuminator is attached withNVD. Use anode in conjunction with cathode to acceleratethe electrons. Problems : acceleration causes distortion of image andreduction of the life of the tube.
Uses passive infrared. Uses ambient light provided by the moon and thestars. Doesn’t work well on cloudy or moonless nights. Uses same image-intensifier tube technology asGeneration-0. Same problems as faced by the Generation-0.
Offer improved resolution and performance overGeneration-1 devices. Considerably more reliable. Able to see in extreme low light conditions due to theaddition of microchannel plate(MCP) to the image-intensifier tube. The images are less distorted and brighter.
Currently used by the US Army. Better resolution and sensitivity. Photocathode is made up of Gallium Arsenide-efficient of converting photons to electrons. Tube life is increased
Shows significant improvement in both high- and low-level light environments. No ion barrier in MCP. Reduced background noise. Enhances signal to noise ratio. Images are less distorted and brighter.
It can be splitted in three broad categories: Scopes Goggles Cameras
An increase in nighttime situational awareness forpilots. This would markedly decrease the possibility ofcollisions with terrain or man-made obstructions. It does permit the user to see objects that normallywould not be seen by the unaided eye.
Lack of color discrimination. Neck strain and fatigue. High initial cost to purchase. Require on-going maintenance. Need for recurrent training. Decreased field of aided view .
.BMWs Night Vision withPedestrian Detection systemallows drivers to see what (orwho) is down the road -- evenon the darkest nights.