night vision technologyNight vision

CENTURION UNIVERSITY OF
TECHNOLOGYAND 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 two
identical or mirror-symmetrical telescopes mounted side-by-side and aligned to
point 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 in
view.
 The focused light is scanned by an infrared-detector elements. The detector
elements create a very detailed temperature pattern called a thermogram. It
only takes about one-thirtieth of a second for the detector array to obtain
the temperature information to make the thermogram. This information is
obtained from several thousand points in the field of view of the detector.
 The thermogram created by the detector elements is translated into electric
impulses.
 The impulses are sent to a signal-processing unit, a circuit board with a
dedicated chip that translates the information from the elements into data
for the display.
 The signal-processing unit sends the information to the display, where it
appears as various colors depending on the intensity of the infrared
emission. The combination of all the impulses from all of the elements
creates 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

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