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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