Night vision-tech-sanketh

NIGHT VISION TECHNOLOGY ( Night Vision Device ) PROJECT GUIDE: ANUSH PRESENTED BY: SANKETH

WHAT WE WILL COVER ! What is night vision Types of night vision Night vision approaches The night vision technology Working of night vision device Generations Applications Conclusion References

It is quite easy to see everything during the day... But at night, we can see very little . Night Vision device lets us see again

What is Night Vision ?? Ability to see in dark environment Whether by biological or technological means, night vision is made possible by a combination of two approaches: sufficient spectral range, and sufficient intensity range . Humans have poor night vision compared to many animals, in part because the human eye does not have a tapetum lucidum The tapetum lucidum (Latin: "bright tapestry", plural tapeta lucida ) is a layer of tissue in the eye of many animals, that lies immediately behind or sometimes within the retina. It reflects visible light back through the retina, increasing the light available to the photoreceptors. This improves vision in low-light conditions.

Types of Night Vision Be it biological or technical it based on two Night Vision Approaches- (i)Spectral range (ii)Intensity range Depending upon the way it is implemented it is broadly classified into two types (i) Biological Night vision (ii) Technical Night vision

Night Vision Approaches Spectral range : Night-useful spectral range techniques make the viewer sensitive to types of light that would be invisible to a human observer. Human vision is confined to a small portion of the electromagnetic spectrum called visible light. Enhanced spectral range allows the viewer to take advantage of non-visible sources of electromagnetic radiation (such as near-infrared or ultraviolet radiation). Some animals can see well into the infrared and/or ultraviolet compared to humans, enough to help them see in conditions humans cannot.

Intensity range : Sufficient intensity range is simply the ability to see with very small quantities of light. Although the human visual system can, in theory, detect single photons under ideal conditions, the neurological noise filters limit sensitivity to a few tens of photons even in ideal conditions. Many animals have better night vision than humans do, Enhanced intensity range is achieved via technological means through the use of an image intensifier, or other very low-noise and high-sensitivity array of photo detectors.

Why do NVD devices always show images in hues of green? The image is green because the phosphor is green in colour that is good for human eye to pick up detail

A tank from World War II equipped with a search light used for night combat.

Night Vision Device 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 the military and law enforcement agencies, but are available to civilian users. The figure shows night vision goggle

EXAMPLES : 1. 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 handsfree use with a harness or helmet attachment

2. Another example is binoculars night vision device. Binocular telescopes , or binoculars (also known as field glasses), are two identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects.

3. Another Example is monocular situated on the gun. The figure shows this type of night vision device

Working of Night Vision devices Night Vision technology consists of two major types: image intensification (light amplification) and Thermal imaging(infrared).

IMAGE INTENSIFICATION It is also called light amplification It is less expensive than thermal Light amplification technology takes the small amount of light, such as moonlight or starlight, that is in the surrounding area, 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 over 10 million channels. As the electrons travel through and strike the walls of the channels, thousands more electrons are released. These multiplied electrons then bounce off of a phosphor screen which converts the electrons back into photons and lets you see an impressive nighttime view even when it's really dark.

All image intensified night vision products on the market today have one thing in common: they produce a green output image

PARTS OF NIGHT VISION DEVICE Image intensifier tube Phosphor screen Objective lens Infrared illuminator

WORKING OF THERMAL IMAGING This method do not require any ambient light at all. principle -: All objects emit infrared energy as a function of their temperature. 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. These create detailed temperature pattern called a thermogram . The thermogram created by the detector elements is translated into electric impulses. The impulses are sent to 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 infrared emission.

Thermal images are normally black and white in nature, where black objects are cold and white objects are hot. Some thermal cameras show images in color. This false color distinguishes between objects at different temperatures

TYPES OF THERMAL IMAGING DETECTORS Un-cooled Infrared Detector: Common type The infrared-detector elements are contained in a unit that operates at room temperature. Bulky in size. Cooled Infrared Detector: Expensive and susceptible to damage. infrared-detector elements are sealed inside a container that cools them to below 32 F . cooled systems can see a distance more than 1,000 ft (300 m) away.

Un-Cooled This is the most common type of thermal-imaging device. 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.

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 32 F (zero C). The advantage of such a system is the incredible resolution and sensitivity that result from cooling the elements. Cryogenically-cooled systems can "see" a difference as small as 0.2 F (0.1 C) from more than 1,000 ft (300 m) away, which is enough to tell if a person is holding a gun at that distance..

Continue…… Unlike traditional most night-vision equipment which uses image-enhancement technology, thermal imaging is great for detecting people or working in near-absolute darkness with little or no ambient lighting (i.e. stars, moonlight, etc, )

NIGHT VISION DEVICES Night vision devices are basically divided into three categories: Scopes: They are monocular normally handheld or mounted on a weapon. Goggles: They are binocular and worn on the head. Cameras: Used for transmission or recording of images mostly if the location is fixed.

GENERATIONS:- Generation 1 : eg:-M1,M4 Generation 2 : eg:-AN/PVS-2 Generation 3 : eg:-AN/PVS-4 , SUPER GEN Generation 4 : eg:-AN/PVS-7 , AN/PVS-14 NVS-7 ,NVS-14

GENERATION 1 The first night vision devices, the M1 and M3 infrared night sighting devices, also known as the "sniperscope" or "snooperscope", were introduced by the US Army in World War II, and also used in the Korean War, to assist snipers. They were active devices, using a large infrared light source to illuminate targets. Their image intensifier tubes function using an anode and an S-1 photocathode, made primarily of silver, caesium and oxygen to accelerate the electrons

GENERATION 2 Second generation passive devices, introduced during the Vietnam War were an adaptation of earlier active Gen 1 technology, and rely on ambient light instead of an infrared light source. Using an S-20 photocathode, their image intensifiers produce a light amplification of around 1000x, but are quite bulky and require moonlight to function properly. Examples: AN/PVS-2

GENERATION 3 Third generation devices featured an improved image-intensifier tube utilizing micro-channel plate (MCP) with an S-25 photocathode , resulting in a much brighter image, especially around edges of the lens. This leads to increased illumination in low ambient light environments, such as moonless nights. Light amplification was around 20000x Also improved were image resolution and reliability. Examples: AN/PVS-4 AN/PVS-5 SUPERGEN

GENERATION 4 Fourth generation night vision systems maintain the MCP from Gen II, but now use a photocathode made with gallium arsenide, which further improves image resolution. In addition, the MCP is coated with an ion barrier film for increased tube life. The light amplification is also improved, to around 30000-50000x Examples: AN/PVS-7 NVS-7 AN/PVS-14 NVS-14 XD-4, autogated or not

Continued…… Courtesy of Matt Last GEN 2 GEN 3 % Improvement Photoresponse(ÂµA/Im) 1800 1800 - Signal-to-Noise Ratio 21.0 25 20% Higher Resolution(lp/mm) 64 64 - Halo(mm) 1.25 0.75 40% Smaller Reliability(hours) 10,000 10,000 -

How Far Can We See ?? There are many different variables that can effect the distance that we see with a Night Vision device. First which object we want to see. The larger the object the easier it is too see. Second. Another variable is lighting conditions. The more ambient light we have (starlight, moonlight, infrared light) the better and further we will be able to see .If it is cloudy and overcast then we typically state that we can tell the difference between a male and a female or a dog and a deer at about 75 to 100 yards. If there is ambient light then we can see about 500 yards.

BLACK SPOTS ON THE SCREEN As we look through a night vision device we may notice black spots on the screen. A NVD is similar to a television screen and attracts dust and dirt. Typically these spots can be cleaned. These black spots will not affect the performance or reliability of the night vision device.

APPLICATIONS Military Hunting Wildlife observation Surveillance Security Hidden-object detection Entertainment

Conclusion Today in the 21 st century we have come a long way in the development of night vision technology, from the early 1950’s. Night vision devices are basically designed for utmost defensive purposes. In present scenario the applications of night vision technology is very essential to combat terrorism which is a major problem being faced by mankind.

References 1.WWW.WIKIPEDIA.ORG 2.EN.WIKIPEDIA.ORG/WIKI/NIGHT_VISION_DEVICE 3.WWW.MOROVISION.COM/HOW_THERMAL_IMAGING_WORKS.HTM 4.EN.WIKIPEDIA.ORG/WIKI/NIGHT_VISION

Night vision-tech-sanketh

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