Samir Roll No.-34
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Transcript of Samir Roll No.-34
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A
SEMINAR ON
-NIGHT--VISION-TECHNOLOGY
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WHAT IS NIGHT VISION??
Ability to see in dark.
Night vision is made possible by sufficient spectral & intensityrange.
Humans have poor night vision compared to many animals.
Tapetum lucidum-a layer of tissue present in eyes of manyanimals responsible for night vision
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NIGHT VISION APPROACHES
Spectral range:
.. Human vision confined to small portion
of electromagnetic spectrum
..Night useful spectral range techniques-
make the viewer sensitive to light invisible
to human observer
..Technology emphasizes on enhanced spectral range
(such as near-infrared or ultraviolet radiation)
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NIGHT VISION APPROACHES
Intensity range:
..Ability to see with small quantities of light
..Enhanced intensity range:-
a)image intensifiers
b)gain multiplication CCD
c)photo detectors
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NIGHT VISION
TECHNOLOGY
THERMAL
IMAGING IMAGE
INTENSIFICATION
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WORKING OF THERMAL
IMAGING A special lens focuses on infrared light Focused light scanned by infrared detector elements
Thermogram created translated to electrical signals
Impulses sent to signal processing unit
Signal processing unit sends information to display
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TYPES OF THERMAL IMAGING
DEVICESo Un-cooled:-1.most common type
2.infrared detector unit performs at roomtemperature
3.system is quiet
4.activates immediately
o Cryogenically cooled;-
1.expensive & susceptible to damage2.elements sealed in container which cools to 32F
3.incredible resolution &sensitivity- due to cooling
4.see difference as small as 0.2 F from 1000ft
5.more helpful in detection in no ambient light
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WORKING OF IMAGE
INTENSIFICATION
Also known as light amplification
Less expensive than thermal
Takes small amount of light, converts photons into electrical
energy
Electrons pass through thin disk containing 10 million channels
Wall collisions releases electrons
Electrons bounce off a phosphor screen
Conversion of electrons to photons
Green light produced
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IMAGE INTENSIFIER TUBE
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GENERATIONS Generation 0:-
NVDs used active infrared
example::sniperscope
Generation 1:-
Bulky & use moonlight to function properlyexample::AN/PVS-2
Generation 2:-
light amplification upto 20000xexample::AN/PVS-4,AN/PVS-5,SUPERGEN
Generation 3:-
photocathode made with gallium arsenide
example::AN/PVS-7,NVS-7
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ADVANTAGE OF GEN 3 OVER GEN
2
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NIGHT VISION EQUIPMENTS
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CHARACTERISTICS
Textures, light &dark
Degraded performance by fog & rain
Automatic brightness control
Blooming or halo effect
Black spots
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APPLICATIONS
Common applications for night vision devices include:
Military
Law enforcement
Hunting Wildlife observation
Surveillance
Security
Navigation Hidden-object detection
Entertainment
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Thank
You