14-04-2011, 03:15 PM
[attachment=12204]
PAPER PRESENTATION-2011
NIGHT VISION TECHNOLOGY
PRESENTED BY:
RAHAMATH ALI.S/2K9675
CSE DEPT-2nd YEAR
CAHCET
VELLORE
ABSTRACT:
A night vision device (NVD) is an optical installment 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 term usually refers to a complete unit, including an image intensifier tube, a protective and generally water-resistant housing, and some type of mounting system. Many NVDs also include sacrificial lenses, IR illuminators, and telescopic lenses. NVDs are mounted appropriately for their specific purpose, with more general- purpose devices having more mounting options. For instance, 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 hands free use with a harness or helmet attachment, either as a monocular device, or in aligned pairs for binocular "night vision goggles" which provide a degree of depth perception as do optical binoculars. The AN/PVS-14 may also be attached to a rifle using a Pica tinny rail, in front of an existing telescopic or red dot sight, or attached to a single-lens reflex camera. Other systems, such as the AN/PVS-22 or Universal Night Sight, are designed for a specific purpose, integrating an image intensifier into, for example, a telescopic sight, resulting in a smaller and lighter but less versatile system
INTRDUCTION:
Night vision technology, by definition, literally allows one to see in the dark. 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.
The first thing you probably think of when you see the words 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. And you may have wondered "Do those things really work? Can you actually see in the dark?"
The answer is most definitely yes. With the proper night-vision equipment, you can see a person sanding 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.
In this article, you will learn about the two major night-vision technologies. We'll also
discuss the various types of night-vision equipment and applications. But first, let's talk about infrared light.
THE BASICS:
In order to understand night vision, 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.
Infrared light can be split into three categories:
• 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.
• 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.
• Thermal-infrared (thermal-IR) - Occupying the largest part of the infrared
spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30
microns.
Generations:
Generation 0 -
The earliest (1950's) night vision products were based on image
conversion, rather than intensification. They required a source of invisible infrared (IR) light mounted on or near the device to illuminate the target area.
Generation 1 - The "starlight scopes" of the 1960's (Vietnam Era) have three image
intensifier tubes connected in a series. These systems are larger and heavier than Gen 2 and Gen 3. The Gen 1 image is clear at the center but may be distorted around the edges. (Low-cost Gen 1 imports are often mislabeled as a higher generation.
Figure 1 illustrates first-generation night vision. [Not a great topic sentence but it does has the advantage of calling attention to the figure.] Incoming light is collimated by fiber optic plates before impacting a photocathode t which releases electrons, which in turn impact a phosphor screen. The excited screen emits green light into a second fiber optic plate, and the process is repeated. The complete process is repeated three times providing an overall gain of 10,000.
Generation 2 -
The micro channel plate (MCP) electron multiplier prompted Gen 2 development 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 microchannel plate. Figure 2 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 (half the diameter of a human hair).
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.
[No topic sentence. Indeed one might have moved this material to the front in a more
dramatic way, perhaps by calling attention to the movie `Silence of the Lambs.'] slight
green tint similar to some sunglasses. The apparent lighting of the landscape on a dark night is comparable to what the unaided eye would see on a clear winter night with fresh snow on the ground and a full moon.
Generation 3 -
Two major advancements characterized development of Gen 3 in the
late 1970s and early 1980s: the gallium arsenide (GaAs) 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.
Generation 4 -
For a good explanation of this commonly misunderstood advancement
in night vision technology. When discussing night vision technology, you also may hear the term "Omnibus" or "OMNI". The U.S. Army procures night vision devices through multi-year/multi-product contracts referred to as "Omnibus" - abbreviated as "OMNI". For each successive OMNI contract, ITT has provided Gen 3 devices with increasingly higher performance. ( See range detection chart directly below) Therefore, Gen 3 devices may be further defined as OMNI 3, 4, 5, etc. Current Omnibus contract as of 2006 is OMNI 7.
If you're using night vision to find a lost person in the woods, to locate boats or buoys on the water, or to stargaze into the wilderness, you need Generation 3 because it creates the best images when there is very little ambient light. Generation 2 may be the choice in situations with higher levels of ambient light.
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.
1. Textures, Light and Dark
2. Depth Perception
3. Fog and Rain
4. Honeycomb
5. Black Spots
Equipment and Applications:
Night-vision equipment can be split into three broad categories:
• 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.
• 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.
• 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.
Applications:
Common applications for night vision include:
• Military
• Law enforcement
• Hunting
• Wildlife observation
• Surveillance
• Security
• Navigation
• Hidden-object detection
• Entertainment
Night vision Home Security Camera
ADVANTAGES & DISADVANTAGES OF NIGHT VISION TECHNOLOGY:
ADVANTAGES:
=>Night vision devices (NVDs) provide night fighters with the ability to see, maneuver and shoot at night or during periods of reduced visibility.
=>The Army used two different types of NVDs – image intensifiers and thermals. =>Image-Intensifying Devices are based upon light amplification and must have some light available.
=>These devices can amplify the available light from 2,000 to 5,000 times. Thermal Forward-Looking Infrared (FLIR) detectors – sometimes called “sensors” – work by sensing the temperature difference between an object and its environment.
=>FLIR systems are installed on certain combat vehicles and helicopters.
DIS-ADVANTAGES:
=>The main dis advantage is we are loosing our direct contact of eye by this technology.
=>The another dis advantage is we are forgetting the present world & thinking the entirely different future world so that we are not taking care of present world technology.
CONCLUTION:
Although the term ``night vision'' currently encompasses three distinct technologies, it is the evolution of image intensification technology that first made devices practical and widely used.
REFERENCE:
http://electronics.howstuffworksnightvision3.html
http://nightvisionmilitary/militaryhome.html
http://physics.ohio-state.edu/~wilki...index.html
http://atncorpHowNightVisionWorks
http://morovisionhownightvisionworks.htm
http://alanaecologyacatalog/Introduction_to_ Nightvision.html
“THANK YOU”
PAPER PRESENTATION-2011
NIGHT VISION TECHNOLOGY
PRESENTED BY:
RAHAMATH ALI.S/2K9675
CSE DEPT-2nd YEAR
CAHCET
VELLORE
ABSTRACT:
A night vision device (NVD) is an optical installment 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 term usually refers to a complete unit, including an image intensifier tube, a protective and generally water-resistant housing, and some type of mounting system. Many NVDs also include sacrificial lenses, IR illuminators, and telescopic lenses. NVDs are mounted appropriately for their specific purpose, with more general- purpose devices having more mounting options. For instance, 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 hands free use with a harness or helmet attachment, either as a monocular device, or in aligned pairs for binocular "night vision goggles" which provide a degree of depth perception as do optical binoculars. The AN/PVS-14 may also be attached to a rifle using a Pica tinny rail, in front of an existing telescopic or red dot sight, or attached to a single-lens reflex camera. Other systems, such as the AN/PVS-22 or Universal Night Sight, are designed for a specific purpose, integrating an image intensifier into, for example, a telescopic sight, resulting in a smaller and lighter but less versatile system
INTRDUCTION:
Night vision technology, by definition, literally allows one to see in the dark. 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.
The first thing you probably think of when you see the words 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. And you may have wondered "Do those things really work? Can you actually see in the dark?"
The answer is most definitely yes. With the proper night-vision equipment, you can see a person sanding 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.
In this article, you will learn about the two major night-vision technologies. We'll also
discuss the various types of night-vision equipment and applications. But first, let's talk about infrared light.
THE BASICS:
In order to understand night vision, 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.
Infrared light can be split into three categories:
• 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.
• 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.
• Thermal-infrared (thermal-IR) - Occupying the largest part of the infrared
spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30
microns.
Generations:
Generation 0 -
The earliest (1950's) night vision products were based on image
conversion, rather than intensification. They required a source of invisible infrared (IR) light mounted on or near the device to illuminate the target area.
Generation 1 - The "starlight scopes" of the 1960's (Vietnam Era) have three image
intensifier tubes connected in a series. These systems are larger and heavier than Gen 2 and Gen 3. The Gen 1 image is clear at the center but may be distorted around the edges. (Low-cost Gen 1 imports are often mislabeled as a higher generation.
Figure 1 illustrates first-generation night vision. [Not a great topic sentence but it does has the advantage of calling attention to the figure.] Incoming light is collimated by fiber optic plates before impacting a photocathode t which releases electrons, which in turn impact a phosphor screen. The excited screen emits green light into a second fiber optic plate, and the process is repeated. The complete process is repeated three times providing an overall gain of 10,000.
Generation 2 -
The micro channel plate (MCP) electron multiplier prompted Gen 2 development 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 microchannel plate. Figure 2 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 (half the diameter of a human hair).
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.
[No topic sentence. Indeed one might have moved this material to the front in a more
dramatic way, perhaps by calling attention to the movie `Silence of the Lambs.'] slight
green tint similar to some sunglasses. The apparent lighting of the landscape on a dark night is comparable to what the unaided eye would see on a clear winter night with fresh snow on the ground and a full moon.
Generation 3 -
Two major advancements characterized development of Gen 3 in the
late 1970s and early 1980s: the gallium arsenide (GaAs) 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.
Generation 4 -
For a good explanation of this commonly misunderstood advancement
in night vision technology. When discussing night vision technology, you also may hear the term "Omnibus" or "OMNI". The U.S. Army procures night vision devices through multi-year/multi-product contracts referred to as "Omnibus" - abbreviated as "OMNI". For each successive OMNI contract, ITT has provided Gen 3 devices with increasingly higher performance. ( See range detection chart directly below) Therefore, Gen 3 devices may be further defined as OMNI 3, 4, 5, etc. Current Omnibus contract as of 2006 is OMNI 7.
If you're using night vision to find a lost person in the woods, to locate boats or buoys on the water, or to stargaze into the wilderness, you need Generation 3 because it creates the best images when there is very little ambient light. Generation 2 may be the choice in situations with higher levels of ambient light.
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.
1. Textures, Light and Dark
2. Depth Perception
3. Fog and Rain
4. Honeycomb
5. Black Spots
Equipment and Applications:
Night-vision equipment can be split into three broad categories:
• 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.
• 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.
• 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.
Applications:
Common applications for night vision include:
• Military
• Law enforcement
• Hunting
• Wildlife observation
• Surveillance
• Security
• Navigation
• Hidden-object detection
• Entertainment
Night vision Home Security Camera
ADVANTAGES & DISADVANTAGES OF NIGHT VISION TECHNOLOGY:
ADVANTAGES:
=>Night vision devices (NVDs) provide night fighters with the ability to see, maneuver and shoot at night or during periods of reduced visibility.
=>The Army used two different types of NVDs – image intensifiers and thermals. =>Image-Intensifying Devices are based upon light amplification and must have some light available.
=>These devices can amplify the available light from 2,000 to 5,000 times. Thermal Forward-Looking Infrared (FLIR) detectors – sometimes called “sensors” – work by sensing the temperature difference between an object and its environment.
=>FLIR systems are installed on certain combat vehicles and helicopters.
DIS-ADVANTAGES:
=>The main dis advantage is we are loosing our direct contact of eye by this technology.
=>The another dis advantage is we are forgetting the present world & thinking the entirely different future world so that we are not taking care of present world technology.
CONCLUTION:
Although the term ``night vision'' currently encompasses three distinct technologies, it is the evolution of image intensification technology that first made devices practical and widely used.
REFERENCE:
http://electronics.howstuffworksnightvision3.html
http://nightvisionmilitary/militaryhome.html
http://physics.ohio-state.edu/~wilki...index.html
http://atncorpHowNightVisionWorks
http://morovisionhownightvisionworks.htm
http://alanaecologyacatalog/Introduction_to_ Nightvision.html
“THANK YOU”
