16-03-2011, 04:29 PM
presented by:
Y. Shiva kumar
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NIGHT VISION TECHNOLOGY
Introduction:
NVT allows us to see in the dark
Originally developed for military use
Now used for site security, surveillance as well as search and rescue
Evolved from bulky optical instruments in lightweight goggles through the advancement of image intensification technology.
Types of night vision:
Categorized by generations
Each substantial change NVT establishes a new generation
Categorized into:
Generations- 0 , 1, 2 , 3 , 4 .
Generation-0:
Created by US Army
Uses active infrared
A projection unit called IR illuminator is attached
Full moon operation
Use anode in conjunction with cathode to accelerate the electrons
Problems –acceleration causes distortion of image as well as reduction of life of the tube
Also, it was quickly duplicated by the hostile nations
Generation-1 (1960’s):
Uses passive infrared
Uses ambient light provided by the moon and the stars
Don’t require a source of projected infrared light
Don’t work well on cloudy or moonless nights
One quarter moon operation
Uses same image-intensifier tube technology as Generation-0
Same problems as faced by the Generation-0
Generation-2 (1970’s)
Offer improved resolution and performance over Generation-1 devices
Considerably more reliable
Able to see in extreme low light conditions due to the addition of microchannel plate(MCP) to the image-intensifier tube
The images are less distorted and brighter
Generation-3 (1990’s)
Currently used by the US Army
Better resolution and sensitivity
Photocathode is made up of Gallium Arsenide
MCP is coated with an ion barrier
Tube life is increased
Generation-4 (2000’s)
Known as “filmless and gated” technology
Shows significant improvement in both high- and low-level light environments
No ion barrier in MCP
Responds quickly to different lightning conditions
Reduced background noise
Enhances signal to noise ratio
Images are less distorted and brighter
Thermal imaging
This technology operates by capturing upper portion of the infrared light spectrum, which is emitted as heat
Hotter objects emit more of this light than the cooler objects
These elements then create a thermogram
Thermogram àelectric pulsesà display data