Night Vision Technology Introduction Night vision technology, by definition, literally allows one to see in the dark. Originally developed for military use, it has . System Assessment and Validation for Emergency Responders (SAVER). Night Vision Technologies Handbook. October Prepared by Space and Naval. Night Vision Technology - Download as Word Doc .doc), PDF File .pdf), Text File .txt) or read online.
|Language:||English, Spanish, Hindi|
|ePub File Size:||26.54 MB|
|PDF File Size:||9.27 MB|
|Distribution:||Free* [*Register to download]|
PDF | This paper portrays the different Night vision techniques."Night Vision" is referenced as innovation that gives us the supernatural. PDF | Night vision based on technology of image intensifier tubes is the oldest electro-optical surveillance technology. However, it receives much less attention . An Introduction to Night Vision Technology. R Hradaynath. Series Editors. Editor- in-Chief. Editors. Mohinder Singh. Ashok Kumar. A Saravanan. Asst Editor.
Hunters and nature enthusiasts use NVDs to maneuver through the woods at night. Detectives and private investigators use night vision to watch people they are assigned to track. Many businesses have permanently-mounted cameras equipped with night vision to monitor the surroundings. A really amazing ability of thermal imaging is that it reveals whether an area has been disturbed -- it can show that the ground has been dug up to bury something, even if there is no obvious sign to the naked eye. Law enforcement has used this to discover items that have been hidden by criminals, including money, drugs and bodies. Also, recent changes to areas such as walls can be seen using thermal imaging, which has provided important clues in several cases. Many people are beginning to discover the unique world that can be found after darkness falls.
The output of image processing may be either an image or, a set of characteristics or parameters related to the image. This paper is about Night vision Technology, by definition, literally allows one to see in the dark, originally developed for military use.
Night vision can work in two very different ways, depending on the technology used. Image enhancement—This works by using the lower portion of the Fig 1. Thermal imaging - This technology operates by using the upper portion of the infrared light Near-infrared near-IR - Closest to visible light, near-IR has spectrum. Both near-IR and mid-IR are used by a variety of electronic devices, including remote controls. Night Vision can work in two different ways The key difference between thermal-IR and the other two is that depending on the technology used.
Infrared light is emitted by an object because of what is 1. Image enhancement- This works by collecting the tiny happening at the atomic level.
They continuously vibrate, that we can easily observe the image. Even the atoms that make up the chairs that we 2. Thermal imaging- This technology operates by sit in are moving around. Solids are actually in motion! Atoms capturing the upper portion of the infrared light can be in different states of excitation. In other words, they can spectrum, which is emitted as heat by objects instead have different energies.
If we apply a lot of energy to an atom, it of simply reflected as light. Hotter objects, such as can leave what is called the ground-state energy level and move warm bodies, emit more of this light than cooler to an excited level. The level of excitation depends on the objects like trees or buildings.
An atom consists of a nucleus containing the protons The Basics: and neutrons and an electron cloud. Think of the electrons in In order to understand night vision, it is important to understand this cloud as circling the nucleus in many different orbits. The amount of energy in alight wave is Although more modern views of the atom do not depict discrete related to its wavelength.
Shorter wavelengths have higher orbits for the electrons, it can be useful to think of these orbits as energy. Of visible light, violet has the most energy, and red has the different energy levels of the atom. In other words, if we the least. Just Next to the visible light spectrums the infrared apply some heat to an atom, we might expect that some of the spectrum. Infrared light can be split into three categories: electrons in the lower energy orbitals would transition to higher energy orbitals, moving farther from the nucleus.
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 32F zeroC. The advantage of such a system is the incredible resolution nd sensitivity that results from cooling the elements.
Cryogenically- Fig 1. When it does, it releases its energy as a photon a particle of light. You see atoms B. Image Enhancement: releasing energy as photons all the time. For example, when the Image-enhancement technology is what most people think of heating element in a toaster turns bright red, the red color is when you talk about night vision.
In fact, image-enhancement caused by atoms excited by heat, releasing red photons. An systems are normally called night-vision devices NVDs.
NVDs excited electron has more energy than a relaxed electron, and rely on a special tube, called an image-intensifier tube, to collect just as the electron absorbed some amount of energy to reach and amplify infrared and visible light. The gathered light is sent to the image-intensifier tube. In most NVDs, the power supply for the image testifier tube receives A.
The tube outputs a Here's how thermal imaging works: high voltage, about 5, volts, to the image-tube components. A special lens focuses the infrared light emitted by all of the The image-intensifier tube has a photocathode, which his used to objects in view. The focused light is scanned by phased array of infrared-detector As the electrons pass through the tube, similar electrons are elements.
The detector elements create a very detailed released from atoms in the tube, multiplying the original number temperature pattern called a thermo gram. It only takes about of electrons by a factor of thousands through the use of a micro one-thirtieth of a second for the detector array to obtain the channel plate MCP in the tube. An MCP is a tiny glass dis chat temperature information to make the thermo gram.
This has millions of microscopic holes micro channels in it, made information is obtained from several thousand points in the field using fiber-optic technology. The MCP is contained in a vacuum of view of the detector array. The lens has a thin strip of graphene between layers of glass that reacts to photons to make dark images look brighter.
Current prototypes only absorb 2. The graphene technology can be expanded into other uses, like car windshields, to increase night driving abilities. The US.
Army is interested in the technology to potentially replace night-vision goggles. It is particularly sensitive to infrared waves that are mid-long lengths. Low cost and larger semiconductors frequently cause atomic spacing to decrease leading to size mismatch defects. This technology was designed with night-time military operations in mind.
Different models introduced around the same time use the same type of batteries and mechanism for mounting on the weapon. The multi-weapon models have replaceable elevation scales, with one scale for the ballistic arc of each supported weapon.
The weapons supported include the AK family, sniper rifles , light machine guns and hand-held grenade launchers. The counter-sniper night sight is an active system that uses laser pulses from a laser diode to detect reflections from the focal elements of enemy optical systems and estimate their range.
Legality[ edit ] Certain countries e. Hungary and other European Union members regulate possession and or use of night-vision devices.
An MCP is a tiny glass disc that has millions of microscopic holes microchannels in it, made using fiber-optic technology. The MCP is contained in a vacuum and has metal electrodes on either side of the disc. Each channel is about 45 times longer than it is wide, and it works as an electron multiplier.
When the electrons from the photo cathode hit the first electrode of the MCP, they are accelerated into the glass microchannels by the 5,V bursts being sent between the electrode pair. As electrons pass through the microchannels, they cause thousands of other electrons to be released in each channel using a process called cascaded secondary emission. 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 leaving the channel where only a few entered.
An interesting fact is that the microchannels in the MCP are created at a slight angle about a 5-degree to 8-degree bias to encourage electron collisions and reduce both ion and direct-light feedback from the phosphors on the output side. These electrons maintain their position in relation to the channel they passed through, which provides a perfect image since the electrons stay in the same alignment as the original photons. The energy of the electrons causes the phosphors to reach an excited state and release photons.
Night-vision images are known for their eerie green tint These phosphors create the green image on the screen that has come to characterize night vision 1 The green phosphor image is viewed through another lens, called the ocular lens, which allows you to magnify and focus the image. The NVD may be connected to an electronic display, such as a monitor, or the image may be viewed directly through the ocular lens.
Generations The earliest '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. The "starlight scopes" of the '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. 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, Generation 2 The micro channel plate MCP electron multiplier prompted Gen 2 development in the s. 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.
Each channel, approximately 0. A single electron entering a channel initiates an avalanche process of secondary emission, under influence of an applied voltage, freeing hundreds of electrons.