This document provides an overview of night vision technology. It discusses how night vision works by collecting tiny amounts of light, including infrared light, and amplifying it so that images can be seen in dark conditions. It describes the two main types of night vision - image enhancement, which amplifies available light, and thermal imaging, which detects infrared light emitted as heat from objects. The document outlines the technologies used in night vision, including image intensification, active illumination, and thermal vision. It provides details on how each technology functions.

1. TABLE OF CONTENTS
Sr. No. Contents Page No.
1 Abstract. 2
2 Introduction. 3
3 Overview. 4
4 Technologies Used. 6
5 How Does It Work? 8
6 Overall Design. 10
7 Advantages and Disadvantages. 11
8 Applications. 12
9 Future Scope. 13
10 Conclusion. 14
11 References. 15
LIST OF FIGURES
Fig. No. Figures Page No.
2.1 Basic of Night Vision Technology 5
4.1 Night vision technology 8
4.2 Working of Night Vision Technology 9
5.1 Overall Design of Night Vision Technology 10

2. JIEMS, AKKALKUWA Department of Computer
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ABSTRACT
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 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?”

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CHAPTER 1
INTRODUCTION
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 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.

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CHAPTER 2
OVERVIEW
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. 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. Atoms are constantly in motion. They continuously vibrate, move and rotate.
Even the atoms that make up the chairs that we sit in are moving around. Solids are actually in
motion! Atoms can be in different states of excitation.
In other words, they can have different energies. If we apply a lot of energy to an atom, it
can leave what is called the ground-state energy level and move to an excited level. The level of
excitation depends on the amount of energy applied to the atom via heat, light or electricity. An
atom consists of a nucleus (containing the protons and neutrons) and an electron cloud. Think of
the electrons in this cloud as circling the nucleus in many different orbits. Although more
modern views of the atom do not depict discrete orbits for the electrons, it can be useful to think
of these orbits as the different energy levels of the atom. In other words, if we apply some heat to
an atom, we might expect that some of the electrons in the lower energy orbitals would transition
to higher energy orbitals, moving farther from the nucleus.

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Fig 2.1: basic of night vision technology
Once an electron moves to a higher-energy orbit, it eventually wants to return to the
ground state. When it does, it releases its energy as a photon -- a particle of light. You see atoms
releasing energy as photons all the time.
For example, when the heating element in a toaster turns bright red, the red color is
caused by atoms excited by heat, releasing red photons. An excited electron has more energy
than a relaxed electron, and just as the electron absorbed some amount of energy to reach this
excited level, it can release this energy to return to the ground state. This emitted energy is in the
form of photons (light energy). The photon emitted has a very specific wavelength (color) that
depends on the state of the electron's energy when the photon is released. Anything that is alive
uses energy, and so do many inanimate items such as engines and rockets.
Energy consumption generates heat. In turn, heat causes the atoms in an object to fire off
photons in the thermal-infrared spectrum. The hotter the object, the shorter the wavelength of the
infrared photon it releases. An object that is very hot will even begin to emit photons in the
visible spectrum, glowing red and then moving up through orange, yellow, blue and eventually
white. Be sure to read How Light Bulbs Work, How Lasers Work and How Light Works for
more detailed information on light and photon emission. In night vision, thermal imaging takes
advantage of this infrared.

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CHAPTER 3
TECHNOLOGIES USED
Image intensification
This magnifies the amount of received photons from various natural sources such
as starlight or moonlight. Examples of such technologies include night glasses and low light
cameras. In the military context, Image Intensifiers are often called "Low Light TV" since the
video signal is often transmitted to a display within a control center. LLLTV These are usually
integrated into a sensor containing both visible and IR detectors and the streams are used
independently or in fused mode, depending on the mission at hand's requirements.
The image intensifier is a vacuum-tube based device (photomultiplier tube) that can
generate an image from a very small number of photons (such as the light from stars in the sky)
so that a dimly lit scene can be viewed in real-time by the naked eye via visual output, or stored
as data for later analysis. While many believe the light is "amplified," it is not. When light strikes
a charged photocathode plate, electrons are emitted through a vacuum tube that strike the micro
channel plate that cause the image screen to illuminate with a picture in the same pattern as the
light that strikes the photocathode, and is on a frequency that the human eye can see. This is
much like a CRT television, but instead of color guns the photocathode does the emitting.
Active illumination
Active illumination couples imaging intensification technology with an active source of
illumination in the near infrared (NIR) or shortwave infrared (SWIR) band. Examples of such
technologies include low light cameras.
Active infrared night-vision combines infrared illumination of spectral range 700–
1,000 nm (just below the visible spectrum of the human eye) with CCD cameras sensitive to this
light. The resulting scene, which is apparently dark to a human observer, appears as a
monochrome image on a normal display device. Because active infrared night-vision systems
can incorporate illuminators that produce high levels of infrared light, the resulting images are
typically higher resolution than other night-vision technologies.

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Active infrared night vision is now commonly found in commercial, residential and
government security applications, where it enables effective night time imaging under low-light
conditions. However, since active infrared light can be detected by night-vision goggles, there
can be a risk of giving away position in tactical military operations.
Laser range gated imaging is another form of active night vision which utilizes a high
powered pulsed light source for illumination and imaging. Range gating is a technique which
controls the laser pulses in conjunction with the shutter speed of the camera's detectors. Gated
imaging technology can be divided into single shot, where the detector captures the image from a
single light pulse, and multi-shot, where the detector integrates the light pulses from multiple
shots to form an image. One of the key advantages of this technique is the ability to perform
target recognition rather than mere detection, as is the case with thermal imaging.
Thermal vision
Thermal imaging detects the temperature difference between the background and the
foreground objects. Some organisms are able to sense a crude thermal image by means of special
organs that function as bolometers. This allows thermal infrared sensing in snakes, which
functions by detection of thermal radiation.
Thermal imaging cameras are excellent tools for night vision. They detect thermal
radiation and do not need a source of illumination. They produce an image in the darkest of
nights and can see through light fog, rain and smoke (to a certain extent). Thermal imaging
cameras make small temperature differences visible. Thermal imaging cameras are widely used
to complement new or existing security networks, and for night vision on aircraft, where they are
commonly referred to as "FLIR" (for "forward-looking infrared"). When coupled with additional
cameras (for example, a visible camera or SWIR) multispectral sensors are possible, which take
advantage of the benefits of each detection band capabilities.

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CHAPTER 4
HOW DOES IT WORK?
"Night Vision" as referenced here is that technology that provides us with the miracle of
vision in total darkness and the improvement of vision in low light environments.
This technology is an amalgam of several different methods each having its own
advantages and disadvantages. The most common methods as described below are Low-Light
Imaging, Thermal Imaging and Near-infrared Illumination. The most common applications
include night driving or flying, night security and surveillance, wildlife observation, sleep lab
monitoring and search and rescue. A wide range of products are available to suit the various
requirements that may exist for these applications:
HOW THEY WORK:
This method of night vision amplifies the available light to achieve better vision. An
objective lens focuses available light (photons) on the photocathode of an image intensifier. 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.
Fig 4.1: Night Vision
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 because the human eye can differentiate more shades of green than any other color,
allowing for greater differentiation of objects in the picture.

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Fig 4.2: Working of Night Vision Technology
All image intensifiers operate in the above fashion. Technological differences over the past
40 years have resulted in substantial improvement to the performance of these devices. The
different paradigms of technology have been commonly identified by distinct generations of
image intensifiers. Intensified camera systems usually incorporate an image intensifier to create a
brighter image of the low-light scene which is then viewed by a traditional camera.
 Fiber optic plates collimate incoming light before impacting a photo cathode 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.

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CHAPTER 5
OVERALL DESIGN
 In second-generation night visions the addition of the micro channel plate (MCP)
collimated electron flow and increased the light-amplification gain Current image
intensifiers incorporate their predecessor's resolution with additional light amplification
 The multi alkali photo cathode 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 5.1: Overall Design of Night Vision Technology

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CHAPTER 6
ADVANTAGES
 Excellent low-light level sensitivity.
 Enhanced visible imaging yields the best possible. Recognition and identification
performance.
 High resolution.
 Low power and cost.
 Ability to identify people.
DISADVANTAGES
 Because they are based on amplification methods, some light is required. This
method is not useful when there is essentially no light.
 Inferior daytime performance when compared to daylight-only methods.
 Possibility of blooming and damage when observing bright sources under low-light
conditions.

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CHAPTER 6
APPLICATIONS
Common applications for night vision include:
 Military
 Law enforcement
 Hunting
 Wildlife observation
 Surveillance
 Security
 Navigation
 Hidden-object detection
 Entertainment

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FUTURE SCOPE
The Army is pushing night vision technology into the digital realm. Future night vision
goggles are being designed not just to see better at night but also to allow soldiers to share
images of what they see with other soldiers who may be miles away.
The night vision industry is making itself available to the non-military consumer market.
While prices are still high, as demand increases, the price may decrease until the technology is
fairly affordable. The technology is already being used by law enforcement and search-and-
rescue teams. As the products become more in the price range of consumers, and because the
images viewed can be recorded by video cameras or as photographs, more photographers,
wildlife watchers, boaters, campers, and many others may begin to use night vision technology
in more innovative ways.

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CONCLUSION
 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.

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REFERENCES
• http://www.google.co.in
• http://www.photonis.com/nightvision/products
• http://www.irinfo.org
• http://www.wikipedia.org