CENTURION UNIVERSITY OF

TECHNOLOGY AND MANAGEMENT

NIGHT VISION TECHNOLOGY

PRESENTED BY:-

AMIT SATYAM

110101ECR108

Contents..

What is night vision

Night Vision Approaches

The night vision technology

Working of night vision device

Generations

Applications

Advantage

Disadvantage

Conclusion

References

What is Night Vision ???

Ability to see in dark environment.

Whether by biological or technological means, night vision is made possible by a

combination of two approaches: sufficient spectral range, and sufficient intensity

range.

Humans have poor night vision compared to many animals, in part because the

human eye does not have a tapetum lucidum.

The tapetum lucidum(Latin: "bright tapestry", plural tapeta lucida) is a layer of

tissue in the eye of many animals, that lies immediately behind or sometimes within

the retina. It reflects visible light back through the retina, increasing the light

available to the photoreceptors. This improves vision in low-light conditions.

Night Vision Approaches

Spectral range :

Night-useful spectral range techniques make the viewer sensitive to types

of light that would be invisible to a human observer.

Human vision is confined to a small portion of the electromagnetic

spectrum called visible light.

Enhanced spectral range allows the viewer to take advantage of non-

visible sources of electromagnetic radiation (such as near-infrared or

ultraviolet radiation).

Some animals can see well into the infrared and/or ultraviolet compared to

humans, enough to help them see in conditions humans cannot.

INTENSITY RANGE

Sufficient intensity range is simply the ability to see with very small

quantities of light.

Although the human visual system can, in theory, detect single photons

under ideal conditions, the neurological noise filters limit sensitivity to a

few tens of photons even in ideal conditions.

Many animals have better night vision than humans do,

Enhanced intensity range is achieved via technological means through the

use of an image intensifier, gain multiplication CCD, or other very low-

noise and high-sensitivity array of photo detectors.

Night Vision Device

A night vision device (NVD) is

an optical instrument that allows

images to be produced in levels of

light approaching total darkness.

They are most often used by the

military and law enforcement

agencies but are available to

civilian users.

The figure shows night vision

goggle.

EXAMPLES :

1.

the AN/PVS-14 is a

monocular night vision

device in use with the

US military as well as

by civilians. It may be

mounted on the user's

head for handsfree use

with a harness or

helmet attachment

2.

Another example is binoculars night vision device.

Binocular telescopes, or binoculars (also known as field glasses), are twoidentical or mirror-symmetrical telescopes mounted side-by-side and aligned topoint accurately in the same direction, allowing the viewer to use both eyes(binocular vision) when viewing distant objects.

3.

Another Example is

monocular situated on the

gun. The figure shows

this type of night vision

device

Working of Night Vision devices

Night Vision technology consists of two major types:

i. image intensification (light amplification) and

ii. Thermal imaging(infrared).

IMAGE INTENSIFICATION

It is also called light amplification

It is less expensive than thermal

Light amplification technology takes

the small amount of light, such as

moonlight or starlight, that is in the

surrounding area, and converts the

light energy (scientists call it

photons), into electrical energy

(electrons)

These electrons pass through a thin

disk that's about the size of a quarter

and contains over 10 million

channels.

As the electrons travel through and

strike the walls of the channels,

thousands more electrons are

released.

Cont…. These multiplied electrons then bounce off of a phosphor screen which

converts the electrons back into photons and lets you see an impressive

night time view even when it's really dark.

All image intensified night vision products on the market today have one

thing in common: they produce a green output image

WORKING OF THERMAL IMAGING

A special lens focuses the infrared light emitted by all of the objects inview.

The focused light is scanned by an infrared-detector elements. The detectorelements create a very detailed temperature pattern called a thermogram. Itonly takes about one-thirtieth of a second for the detector array to obtainthe temperature information to make the thermogram. This information isobtained from several thousand points in the field of view of the detector.

The thermogram created by the detector elements is translated into electricimpulses.

The impulses are sent to a signal-processing unit, a circuit board with adedicated chip that translates the information from the elements into datafor the display.

The signal-processing unit sends the information to the display, where itappears as various colors depending on the intensity of the infraredemission. The combination of all the impulses from all of the elementscreates the image.

Types Of Thermal Imaging Device There are two common types of thermal-imaging devices:

i. Un –Cooled

ii. cryogenically Cooled

Un-Cooled

This is the most common type of thermal-imaging device. The infrared-detector

elements are contained in a unit that operates at room temperature. This type of

system is completely quiet, activates immediately and has the battery built right in.

Cryogenically Cooled

More expensive and more susceptible to damage from rugged use, these systems

have the elements sealed inside a container that cools them to below 32 F (zero C).

The advantage of such a system is the incredible resolution and sensitivity that

result from cooling the elements. Cryogenically-cooled systems can "see" a

difference as small as 0.2 F (0.1 C) from more than 1,000 ft (300 m) away, which is

enough to tell if a person is holding a gun at that distance.

Unlike most night-vision equipment which uses image-enhancement technology,

thermal imaging is great for detecting people or working in near-absolute darkness

with little or no ambient lighting (i.e. stars, moonlight, etc, )

GENERATIONS

Generation 0

Generation 1

Generation 2

Generation 3

GENERATION 0

The first night vision devices, the M1 and M3 infrared night sighting

devices, also known as the "sniperscope" or "snooperscope", were

introduced by the US Army in World War II, and also used in the Korean

War, to assist snipers.

They were active devices, using a large infrared light source to illuminate

targets.

Their image intensifier tubes function using an anode and an S-1

photocathode, made primarily of silver, cesium and oxygen to accelerate

the electrons

GENERATION 1

First generation passive devices, introduced during the Vietnam War were

an adaptation of earlier active Gen 0 technology, and rely on ambient light

instead of an infrared light source. Using an S-20 photocathode, their image

intensifiers produce a light amplification of around 1000x, but are quite

bulky and require moonlight to function properly.

Examples:

i. AN/PVS-2

GENERATION 2

Second generation devices featured an improved image-intensifier tube

utilizing micro-channel plate (MCP) with an S-25 photocathode , resulting in a

much brighter image, especially around edges of the lens. This leads to

increased illumination in low ambient light environments, such as moonless

nights. Light amplification was around 20000x Also improved were image

resolution and reliability.

Examples:

a) AN/PVS-4

b) N/PVS-5

c) SUPERGEN

GENERATION 3

Third generation night vision systems maintain the MCP from Gen II, but now

use a photocathode made with gallium arsenide, which further improves image

resolution. In addition, the MCP is coated with an ion barrier film for increased

tube life. The light amplification is also improved.

Examples:

a) AN/PVS-7

b) NVS-7

c) AN/PVS-14

d) NVS-14

e) XD-4

Advantage of Gen 3 over Gen 2

Gen 3 technology improves night operational effectiveness for military

users of night vision goggles and other night vision devices.

The filmless MCP provides a higher signal-to-noise ratio than Gen 2,

resulting in better image quality (less scintillation) under low-light

conditions.

The gated power supply further improves image resolution under high light

conditions, and the reduced halo minimizes interference from bright light

sources. These improvements also substantially increase the detection

range of the system.

How Far Can We See ??

There are many different variables that can effect the distance that you we

see with a Night Vision device.

First which object we want to see.

The larger the object the easier it is too see.

Second. Another variable is lighting conditions. The more ambient light we

have (starlight, moonlight, infrared light) the better and further we will be

able to see .If it is cloudy and overcast then we typically state that we can

tell the difference between a male and a female or a dog and a deer at about

75 to 100 yards.

If there is ambient light then we can see about 500 yards.

BLACK SPOTS ON THE SCREEN

As we look through a night vision

device we may notice black spots

on the screen. A NVD is similar to

a television screen and attracts

dust and dirt. Typically these spots

can be cleaned.

These black spots will not affect

the performance or reliability of

the night vision device.

APPLICATIONS

Military

Hunting

Wildlife observation

Security

Hidden-object detection

ADVANTAGES

An increase in nighttime situational awareness for pilots.

This would markebly decrease the possibility of collisions with terrain or

man-made obstructions.

It does permit the user to see objects that normally would not be seen by

the unaided eye.

DISADVANTAGES

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 .

Conclusion

Through night vision device we can see the object in dark

environment.

We have seen four generation of this devices and seen different

ranges.

Initially this device was used by military but now it also available

for civilians.

The innovation and implementation of night vision system has a

great impact on automotive session such as saving many lives

from death reducing accidents at night.

References

http://electronics.howstuffworks.com/nightvision3.html

http://www.nightvision.com/military/militaryhome.html

http://www.physics.ohiostate.edu/~wilkins/writing/Samples/shortme

d/johnmedium/index.html

http://www.atncorp.com/HowNightVisionWorks

http://www.morovision.com/hownightvisionworks.htm

http://www.alanaecology.com/acatalog/Introduction_to_

Nightvision.html

http://www.photonis.com/nightvision/products/supergen/supergen_s

pecifications

http://www.irinfo.org/articles/03-01-2007grossman.html