2. Table of contents
1. Introduction …………………………………………………………………………….… 4-5
1.1. History
1.2.1. Thermal Imaging
1.2.2. Image Enhancement
2. Types of Night Vision ……………………………………………………………………...5
2.1. Biological Night Vision
2.2. Technical Night Vision
3. Working of Technical Night Vision ………………………………………………….….5-9
3.1. Light Basics
/-// 3.1.1. Near-infrared (near-IR)
3.1.2. Mid-infrared (mid-IR)
3.1.3. Thermal-infrared (thermal-IR)
3.2. Thermal Imaging
3.2.1. Uncooled Detector
3.2.2. Cooled Infrared Detector
3.3. Image Intensifier
4. Night Vision Device ……………………………………………………………….…...9-10
4.1. Scopes
.4.2. Goggles
4.3. Cameras
5. Generations ……………………………………………………………………………..10-12
5.1. Generations 0
5.2. Generations 1
5.3. Generations 2
5.4. Generation 3
3. 5.5. Generation 4
6. KEY GENERATION DEVELOPMENTS: ……………………………………………...…12
7. Applications …………………………………………………………………………….……13
7.1 Automobile
8.Characteristics of Night Vision ……………….…………………………………………..…14
8.1 Textures, Light and Dark
8.2 Depth Perception
8.3 Fog and Rain
8.4 Honeycomb
8.5 Black Spots
9. Conclusions …………………………………………………………………………...…14-15
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
4. Abstract
Night vision is a spy or action movie you've seen, in which someone straps on a pair of night-
vision goggles to find someone else in a dark building on a moonless night. With the proper
night-vision equipment, you can see a person standing over 200 yards (183 m) away on a
moonless, cloudy night. Night vision can work in two very different ways, depending on the
technology used.
" Image enhancement - This works by collecting the tiny amounts of light, including the lower
portion of the infrared light spectrum, that are present but may be imperceptible to our eyes, and
amplifying it to the point that we can easily observe the image.
“Thermal imaging - This technology operates by capturing the upper portion of the infrared light
spectrum, which is emitted as heat by objects instead of simply reflected as light. Hotter objects,
such as warm bodies, emit more of this light than cooler objects like trees or buildings.
To study about night vision technology we should first know 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. Night vision technology consists of two major types: light amplification
(or intensification) and thermal (infrared).
Most consumer night vision products are light amplifying devices. All ITT Night Vision
products use light-amplifying technology. This technology takes the small amount of light that's
in the surrounding area (such as moonlight or starlight), 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 more than
10 million channels. As the electrons go through the channels, they strike the channel walls and
thousands more electrons are released. These multiplied electrons then bounce off of a phosphor
screen which converts the electrons back into photons and let you see an impressive nighttime
view even when it's really dark
5. 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!. Originally developed for military use, it has provided the United
States with a strategic military advantage, the value of which can be measured in lives. Federal
and state agencies now routinely utilize the technology for site security, surveillance as well as
search and rescue. Night vision equipment has evolved from bulky optical instruments in
lightweight goggles through the advancement of image intensification technology..
1.1. History
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 shocking 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 rifles 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 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.
Fig 1 :- Early Attempts at Night Vision Technology
6. Two technologies are used for night vision:-
1.2.1. 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.
1.2.2. 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.
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 best night vision in
humans is 30 minutes, but most of the variation occurs within the first five or ten minutes in the
dark. Rhodesian 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
enforces agencies but is available to civilian users. In this technology various types of
instruments are used. Details descriptions of this technology are described in next page.
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.
7. Fig 2:-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.
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 thermo gram.
Fig 3:-The basic of thermal imaging system
8. It only takes about one-thirtieth of a second for the detector array to obtain the
temperature information to make the thermo gram. This information is obtained from several
thousand points in the field of view of the detector array. The thermo gram 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.
It is quite easy to see at day time But at night you can see very little
Thermal imaging lets you see again
Fig 4:-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).
9. 3.3. Image Intensifier
This method of night vision amplifies the available light to achieve better vision.
Diagram is given below. A conventional lens captures the ambient light. This lens focuses
available light (photons) on the photocathode of an image intensifier tube.
Fig 5:-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. A channel 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.
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.
10. Fig 6:- scope (monocular)
.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.
Fig 7:-goggles worn on the head
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.
Fig 8:- Camera
11. 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 heavier than gen2 and gen3. The gen1 clear at the center but may be distorted around the
edges. Figure illustrates 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.
Fig 9:-Generations1
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 for back-to-back tubes - thereby
improving size and image quality. The MCP enabled development of hand held and helmet
mounted goggles. Second-generation image intensification significantly increased gain and
resolution by employing a micro channel plate.
Figure depicts the basic configuration. These two sentences could have been
combined: "Figure2 depicts how second-generation image ... plate." The micro channel plate is
composed of several million microscopic hollow glass channels fused into a disk. Each channel,
12. 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 near infrared. The moon and stars provide light in these
wavelengths, which boosts the effectively available light by approximately 30%, bringing the
total gain of the system to around 30,000.
Fig 10:-Generations2
5.4. Generation 3
Two major advancements characterized development of Gen 3 in the late 1970s and early
1980s: the gallium arsenide photocathode and the ion barrier 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), as demonstrated 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 responded better to bright
sources. Whether you are looking for a night vision scope, a hands-free Generation 4 night
vision 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.
13. Percentage of improving from generation to generation
6. Key GenerationDevelopment:
GENERATION 1 (Developedin 1960's);
Vacuum Tube Technology
Full Moon Operation
Amplification: 1,000
o Operating Life: 2,000 Hours
GENERATION 2 (Developedin 1970's);
o First Micro channel Plate (MCP) Application
o One-Quarter Moon Operation
o Amplification: 20,000
o Operating Life: 2,500 Hours
GENERATION 2+ (1970s)
o Development increased image tube bias voltage to improve gain.
o Additionally, a glass faceplate was added to improve resolution.
GENERATION 3 (Developedin 1990's);
o Improved MCP & Photocathode
o Starlight Operation
o Amplification: 40,000
o Operating Life: 10,000 Hour
GENERATION 3 Enhanced (2000's);
o Improvements in the photocathode and MCP resulted in increased gain and resolution.
14. 7. 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.
Hunters 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
have 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.
7.1 Automobile
BMW’s new Night Vision with Pedestrian Detection system that uses the same
technology that firefighters use to find victims in burning buildings to distinguish between
animals and humans on the road. The passive system uses “far-infrared” technology to scan for
heat, offering considerable depth (1,000 feet, or twice the distance of headlights) and clarity,
even when it’s raining.
Fig 11:-Night Vision Technology in Automobile
15. 8.Characteristics of Night Vision
Using intensified night vision is different from using regular binoculars and/or your own
eyes. Below are some of the aspects of night vision that you should be aware of when you are
using an image intensified night vision system.
8.1 Textures, Light and Dark
Objects that appear light during the day but have a dull surface may appear
darker, through the night vision unit, than objects that are dark during the day but have a highly
reflective surface. For example, a shinny dark colored jacket may appear brighter than a light
colored jacket with a dull surface.
8.2 Depth Perception
Night vision does not present normal depth perception.
8.3 Fog and Rain
Night vision is very responsive to reflective ambient light; therefore, the light reflecting
off of fog or heavy rain causes much more light to go toward the night vision unit and may
degrade its performance.
8.4 Honeycomb
This is a faint hexagonal pattern which is the result of the manufacturing process.
8.5Black Spots
A few black spots throughout the image area are also inherent characteristics of all night
vision technology. These spots will remain constant and should not increase in size or number.
9. Conclusions
Through night vision device we can see the object in dark environment. We have seen
four generation of these 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 purposes but 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 weather. 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.
