This ois the report o night vision technology. according to the report tehir also be ppt in this webside.............

1. 1. Introduction
The word „Night vision‟ itself means the ability to see in low light conditions. Humans have poor
night vision compared to many other animals.So we all might have a question in our mind that is
this really possible to see in the dark night? The answer is most definitely yes. With the proper
night-vision equipment, you can see a person standing over 200 yards (183 m) away on a
moonless, cloudy night!. Originallydeveloped for military use, it has provided the United States
with a strategic militaryadvantage, the value of which can be measured in lives. Federal and state
agencies nowroutinely utilize the technology for site security, surveillance as well as search
andrescue. Night vision equipment has evolved from bulky optical instruments inlightweight
goggles through the advancement of image intensification technology.
The night has always had a mysterious and eerie aura to it, due to the darkness that it
accompanies. Through time, the dark has always been something that a lot of people fear. As
they say, you never know what lurks in the dark. However, as technology developed, the night
has become less of a scary monster and even became a sought after period of the day, all thanks
to the invention of the night vision. If you're wondering how this innovation started in the first
place, read on and learn the history of night vision.It has always been a point that man had to
dominate his enemies but at the same time making little damage as he can.
In the beginning, men fought at daytime since night raids were considered to be very dangerous.
They were and virtually impossible back then. With some time, men realized that surprising their
enemies with attacks were much effective and could be very devastating on their enemies' side.
This was the situation when torches became a hit, especially in the middle Ages. If a torch can
last longer, the better. However, brilliant may torches seem, it gave one big problem- it revealed
the position of the attacker.This problem was answered during the 1940's on the midst of World
War II, by the innovation of night vision. At first, it was only sniper riffles that had this
technology, so that they would have the ability to foresee enemies even from a distance. The use
of this gave a dramatic effect on the whole war's course. Ever since the Germans have found its
usefulness, they have begun developing innovative technology so that they can successfully
dominate even the night.it was during the 1960's Vietnam Era, when military troops began
developing night vision technology. It was this time when the night vision goggles first came out

2. and promoted. There was a remarkable advantage seen on those military divisions that has night
vision goggles compared to those that did not have them. This became the reason why the
government along with the military pushed on with further research about the said technology. In
terms of war, the technology was also used in the war against Iraq. It has proved to be an
extremely excellent tool, especially for defensive purposes and guarding against the militia. The
advantage is also present for thermal vision. Nonetheless, they can get the best of both worlds by
combining both thermal and night vision. Doing this gives overwhelming power over the night.
Nowadays, night vision technology is widely available even to the public. Most likely,
equipments with this feature are used by hunters since it is undeniably a reliable way for them to
detect animals even during night time.
Two technologies are used for night vision:-
(1)Thermal Imaging
This work by collection the tiny amounts of light including the lower portion of infrared light
spectrum that are present but may be imperceptible to your eyes, and amplifying it to the point
that we can easily observe the image.
(2)Image Enhancement
This technology operates by capturing the upper portion of the infrared light spectrum, which is
emitted as heat by the objects instead of simply reflected as light. Hotter object, such as warm
bodies, emit more of this light than cooler objects likes trees or buildings.

3. 2. Types of Night Vision
There are two type night vision such as
2.1. Biological Night Vision
In biological night vision, molecules of rhodopsin in the rods of the eye undergo a change in
shape as light is absorbed by them. The peak rhodopsin build-up time for optimal night vision in
humans is 30 minutes, but most of the adaptation occurs within the first five or ten minutes in the
dark. Rhodopsin in the human rods is insensitive to the longer red wavelengths of light, so many
people use red light to preserve night vision as it will not deplete the eye's rhodopsin stores in the
rods and instead is viewed by the cones.
.Some animals, such as cats, dogs, and deer, have a structure called tapetumlucidum in the back
of the eye that reflects light back towards the retina, increasing the amount of light it captures. In
humans, only 10% of the light that enters the eye falls on photosensitive parts of the retina. Their
ability to see in low light levels may be similar to what humans see when using first or perhaps
second generation image intensifiers
2.2. Technical Night Vision
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 military and law enforce
agencies but are available to civilian users. In this technology various types of instruments are
used.Details descriptions of this technology is described in next page.

4. 3. Working of Technical Night Vision
Night vision can works in two very different ways depending on the technology used. Before
discussing about the types of night vision technology first known basic things of light.
3.1. Light Basics
In order to understand thermal imaging, it is important to understand something about light. The
amount of energy in a light wave is related to its wavelength: Shorter wavelengths have higher
energy. Of visible light, violet has the most energy, and red has the least. Just next to the visible
light spectrum is the infrared spectrum.
Fig1:-Spectrum of light
Infrared light can be split into three categories:-
3.1.1. Near-infrared (near-IR)
Closest to visible light, near-IR has wavelengths that range from 0.7 to 1.3 microns, or 700
billionths to 1,300 billionths of a meter.
3.1.2. Mid-infrared (mid-IR)
Mid-IR has wavelengths ranging from 1.3 to 3 microns. Both near-IR and mid-IR are used by a
variety of electronic devices, including remote controls.

5. 3.1.3. Thermal-infrared (thermal-IR)
Occupying the largest part of the infrared spectrum, thermal-IR has wavelengths ranging from 3
microns to over 30 microns.The key difference between thermal-IR and the other two is that
thermal-IR is emitted by an object instead of reflected off it. Infrared light is emitted by an object
because of what is happening at the atomic level.
Night vision can work in two very different ways, depending on the technology used.
3.2. Thermal Imaging
A special lens focuses the infrared light emitted by all of the objects in view. The focused light is
scanned by a phased array of infrared-detector elements. The detector elements create a very
detailed temperature pattern called a thermogram..
Fig2:-The basic of thermal imaging system
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 array. 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.

6. 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.
It is quite easy to see at day time But at night you can see very little
Thermal imaging lets you see again
Fig3:-Different view
There are two type of thermal imaging detector
3.2.1. Uncooled Detector
This the most common type of thermal imaging detector. The infrared elements are contained in
a unit that operates a room temperature. This type of system is completely quit and activate
immediately and the battery built right in.
3.2.2. Cooled Infrared Detector
More expensive and susceptible to damage from rugged used, these system has cooled inside a
container that cool them below zero c. These the of system can see more than 1000 ft(300m).

7. 3.3. Image Intensifier
This method of night vision amplifies the available light to achieve better vision.Digram is given
below. A conventional lens capture the ambient light. This lens focuses available light (photons)
on the photocathode of an image intensifier tube.
Fig4:-Image intensifier process
The light energy causes electrons to be released from the cathode which are accelerated by an
electric field to increase their speed (energy level). These electrons enter holes in a micro
channel plate and bounce off the internal specially-coated walls which generate more electrons
as the electrons bounce through. This creates a denser “cloud” of electrons representing an
intensified version of the original image.Achannel using a process called cascaded secondary
emissions electrons pass through the micro- channels, they cause thousands of other electrons
to be released in each. Basically, the original electrons collide with the side of the channel,
exciting atoms and causing other electrons to be released. These new electrons also collide with
other atoms, creating a chain reaction that results in thousands of electrons. The final stage of the
image intensifier involves electrons hitting a phosphor screen. The energy of the electrons makes
the phosphor glow. The visual light shows the desired view to the user or to an attached
photographic camera or video device. A green phosphor is used in these applications.

8. 4. Night Vision Device
Night-vision equipment can be split into three broad categories
4.1. Scopes
Normally handheld or mounted on a weapon, scopes are monocular (one eye-piece). Since
scopes are handheld, not worn like goggles, they are good for when you want to get a better look
at a specific object and then return to normal viewing conditions.
Fig5:- scope (monocular)
Depending on the model you can obtain higher power lens sets to economically increase the
observation range of your scope while others can be upgraded with camera adapters to permit
capture of night vision photographs and video. Some scopes can be converted to hands-free
mono-goggles or adapted to weapon mounts to serve as night vision rifle scopes, while others are
best suited to marine applications thanks to their waterproof construction.

9. 4.2. Goggles
While goggles can be handheld, they are most often worn on the head. Goggles are binocular
(two eye-pieces) and may have a single lens or stereo lens, depending on the model. Goggles
are excellent for constant viewing, such as moving around in a dark building.
Fig6:-goggles worn on the head
Many can be converted to long-range scopes and binoculars and some are even weapon
mountable. While all include integrated short-range infrared illuminators that permit map reading
and room-to-room searches in complete darkness, long-range illumination requires the addition
of one of our infrared sports lights.
4.3. Cameras
Cameras with night-vision technology can send the image to a monitor for display or to a VCR
for recording. When night-vision capability is desired in a permanent location, such as on a
building or as part of the equipment in a helicopter, cameras are used. Many of the newer
camcorders have night vision built right in.

10. 5. Generations
These are the generations of night vision technology
5.1. Generations 0
The earliest (1950) night vision products were based on image conversion, rather than
intensification. They required a source of invisible infrared light mounted on or near the device
to illuminate the target area.
5.2. Generations 1
In generation 1 three image intensifier tubes connected in series. These system are larger and
havier than gen2 and gen3. The gen1 clear at the center but may be distorted around the edges.
Figure illustrate that first generation night vision. Incoming light is collimated by fiber optics
plates before impacting the a photocathode which release electron, which is turn impact a
phosphor screen. The excited screen emits green light in to a second fiber plate, and the process
is repeated. The complete process is repeated three times providing an overall gain of 10,000.
Fig7:-Generations1

11. 5.3. Generations 2
The micro channel plate (MCP) electron multiplier prompted Gen 2development in the 1970s.
The "gain" provided by the MCP eliminated the need forback-to-back tubes - thereby improving
size and image quality. The MCP enableddevelopment of hand held and helmet mounted
goggles.Second-generation image intensification significantly increased gain and resolution
byemploying a microchannel plate.
Figure depicts the basic configuration. These two sentences could have been combined:
"Figure2 depicts how second-generation image ... plate." The microchannel plate is composed of
several million microscopic hollow glass channels fused into a disk. Each channel,
approximately 0.0125 mm in diameter, is coated with a special semiconductor which easily
liberates electrons. A single electron entering a channel initiates an avalanche process of
secondary emission, under influence of an applied voltage, freeing hundreds of electrons. These
electrons, effectively collimated by the channel, increase the resolution of the device.With
additional electron optics, details as fine as 0.025 mm can be realized.Current image intensifiers
incorporate their predecessor's resolution with additional light amplification. The multialkali
photocathode is replaced with a gallium arsenide photocathode; this extends the wavelength
sensitivity of the detector into the nearinfrared. The moon and stars provide light in these
wavelengths, which boosts theeffectively available light by approximately 30%, bringing the
total gain of the systemto around 30,000.
Fig8:-Generations2

12. 5.4. Generation 3
Two major advancements characterized development of Gen 3 in thelate 1970s and early 1980s:
the gallium arsenide photocathode and the ionbarrier film on the MCP. The GaAs photocathode
enabled detection of objects at greater distances under much darker conditions. The ion-barrier
film increased the operational life of the tube from 2000 hours (Gen 2) to 10,000 (Gen 3),
asdemonstrated by actual testing and not extrapolation.
5.5.Generation 4
Generation 4 is used to describe the most advanced night vision technology. Referred to as
'Filmless & Gated' image intensifiers by the US Military, Generation 4 image tubes provide a
notable improvement over Gen 3 night vision. They not only offer increased detection range in
pitch-black conditions, but with a dramatically reduced 'halo' they also responsed better to bright
sources. Whether you are looking for a night vision scope, a hands-free Generation 4 night vison
goggles system, or a night vision weapons sight, we can offer a good selection to choose from.
We also have Generation 4 night vision binoculars.
Percentage of improving from generation to generation

13. 6. Applications
These are the common applications of night vision technology
1. Military
2. Hunting
3. Security
4. Navigation
5. Wildlife observations
6. Hidden object detection
The original purpose of night vision was to locate enemy target at night. It is extensively by the
military for that purpose, as well as for navigation and targeting. Police and security often use
both thermal imaging and image enhancement technology, particularly for surveillance. Hunter
are use this to detect the animals and any other birds. Detectives and private investigator use
night vision to watch assigned to track.
Many business have permanently-mounted cameras equipped with night vision to monitor
surroundings. A real amazing ability of thermal imaging, is that it reveals whether an has been
distributed , it can show that the ground has been dug up to bury something, even if there is no
obvious sing to the naked eye. Law enforcement has used this to discover items that has been
hidden by the criminal, including money, drugs and bodies. Also recent changes to area such as
walls can be seen using thermal imaging, which have provided important clues in several cases.
Many people are beginning to discover the unique world that can be found after darkness falls.

14. 7. Conclusions
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.Today in the 21st century we have come a long way in the
development of night vision technology, from the early 1940‟s. Night vision devices are
basically designed for utmost defensive purposesbut the application within the scientific or the
civilian range is often prohibited by law.In present scenario the applications of night vision
technology is very essential to combat terrorism which is a major problem being faced by
mankind.
Finally we have seen that use of night vision devices. we find that night vision device is used in
the presence of ambient light or in case of cloudy whether. There are many types of night vision
devices available in the market but in all these devices one things is common: they produced
green light. so in overcast and cloudy whether the performance of night vision devices decreased
means the detection range is decreased compared to ambient light such as moonlight or starlight.

15. 8. References
http://www.photonis.com/nightvision/products/supergen/supergen_specifica
http://www.irinfo.org/articles/03_01_2007_grossman.html
Www.Wikipedia.Org
En.Wikipedia.Org/Wiki/Night_vision_device
Www.Morovision.Com/How_thermal_imaging_works.Htm
En.Wikipedia.Org/Wiki/Night_vision