how does a night vision device work?

Answer 1

There are two types of night vision devices.

One is based on amplification, or intensification, of existing light, using a high-voltage to cause avalanche multiplication in the intensifier, which is a microchannel structure designed specifically to create a cascade of electrons from a single photon that impinges on a photocathode to create an intensified image. These are the source of the typically green night imagery seen on CNN.:
http://en.wikipedia.org/wiki/Image_intensifier
Image intensifiers operate on reflected ambient light and the image gets progressively noisier as the ambient light level decreases. In a light-tight darkened room, an image intensifier will see nothing but random, self-induced noise.

The other type is a thermal imager, which operates by sensing the radiant energy emitted by all non-zero kelvin objects:
http://en.wikipedia.org/wiki/Thermal_imager
These imagers essentially sense the temperature of objects

Answer 2

Without going into too much scientific detail, the basic principle of night vision devices is that incoming photons strike a photoelectric plate. A photoelectric plate is one which reacts to being struck by photons by releasing a number of charged particles, electrons, for each photon that strikes it.

These electrons are then accelerated through a photomultiplier, which produces even more electrons by using a very high voltage to propel them down a tube. The electrons then strike a phosphor screen, which reacts to them by creating pools of light which is visible to the human eye.

While the above is reasonably accurate, it is necessarily a slight simplification of the processes involved. The most important point to remember is that the most common devices merely amplify the existing light. Consequently, the image is slightly blurry and low resolution, but perfectly adequate for many low level hunting applications.

There are several generations of device, each using slightly different principles to achieve the same result (with differing degrees of success). Some are more technologically advanced than others, and consequently come with different price tags attached to them.

So called second generation devices work by taking the electrons and forcing them through a device known as a micro channel plate (MCP) which multiples them, and produces a much larger stream of electrons which are then propelled towards the phosphor screen as before.

The result is a better image, which is somewhat less fuzzy, and can be viewed whilst moving in reasonable conditions. They also cost about $1,000 more, but well worth it for the hardened night hunter.

There are also third and fourth generation models used in military and police environments which use chemical layers over the phosphor screen to achieve a brighter image with better contrast.

All of the above rely on some light to work effectively – unlike passive scopes, however, they only need a very small amount of light, and can amplify it by up to a thousand times. They will still not work in complete darkness, however, but this is a very rare situation to be in.

For operation in complete darkness, or in cases where extremely high image clarity is a requirement (emergency, police, military and surveillance), an infra red augmented device will be needed..

For futher details-
http://www.rugift.com/night-vision/night-vision-devices-work.htm

Answer 3

While Len'ss are involved, no "lense" does any amplification of any kind of 'light', or anything in the electromagnetic spectrum, which 'light' is a part of. The night vision devices are also not just thermal energy amplifiers. Thermal, or infra red energy, or "light" can be amplified in a special detection tube. Basically, the energy striking this tube causes electrons to be released ,and this flow of electrons is amplified as has been stated by someone else. Light from other sources, such as star light is also used in night vision devices. Any of these sources will be amplified in order to resolve a desired image.

Answer 4

Night Vision Devices, Night Vision Binoculars, Night Vision Mon-
oculars, Night Vision Scopes and Daytime
Rifle Scopes are widely recognized as the
most innovative and highest quality made.


The device is used to see in dark..

Answer 5

any kind of night vision device works on thermal imaging. that means it uses the heat emitting out of any body to make an image. so more heat level means clear imaging. it then makes an out line of that image to show on the screen of an nvd.

Answer 6

Such devices use electron beams. Camera produces the e beam and the reflected beam from objects are absorbed and is analyzed. we see a green colored pictures through electron cameras, especially in battlefields in night

Answer 7

its basically an optical lens that amplifies the ambient light of an area hundreds of times

Answer 8

It lets u see in the dark.