Night vision goggles (NVG)

Night vision goggles (NVG) are a form of optical equipment that allows you to see in the dark. They are most often used by the military.

There are two common types of night vision goggles:

Passive night vision goggles — these pick up any light in the given area and amplify it several thousand times using an image intensifier. Working by the photoelectric effect. As a photon collides with a detector plate, the metal ejects several electrons that are then amplified into a cascade of electrons that lights up a phosphor screen. Often a dim star in the sky is enough to illuminate an entire field. This type is commonly used for war reporting, making the picture green. The color green is chosen because the human eye is most sensitive and able to discern the most shades in green.

Two American soldiers pictured during the Iraq War, 2003Active night vision goggles — these project infrared light (the same type used by a remote control), and produce an image from the light reflected back. These goggles may require an image enhancer to amplify the light. The feature is commonly found on home video cameras, as it suits most consumers' needs for seeing in the dark. Pointing a television remote control at this type of system produces a glaringly bright image.
There are currently goggles that combine both of these technologies to create images that are almost as clear as day. In addition to goggles, night vision technology is also used in rifle scopes, security cameras, binoculars, etc.

Using a Night Vision Device

Using a Night Vision Device by James Hunt


It's difficult to see in the dark. Unless there's some light peeking in through the window or from under a door, our vision is compromised. If we wait a little while, our night vision kicks in, allowing us to see somewhat better. It's not enough that we can read in the dark, but it should be enough to keep us from stumbling into furniture or tripping over the carpet. Sometimes though, our human night vision isn't enough and we need a little help.

That's where technology kicks in. Thanks to science we can use night vision to do all sorts of things. With the proper equipment we can hunt, take pictures or even fight wars in the dark. We can also perform surveillance and search and rescue missions.

Here's how it works: Your night vision product will take existing light and amplify it through an objective lens, which then focuses on an image intensifier. A photocathode located inside the intensifier converts the photon energy into electrons. The electrons in turn strike a phosphor screen creating a viewable image. In reality it looks like you're watching television on a green screen.

Atmospheric conditions can affect night vision. For instance, if it's cloudy, foggy, or overcast, night vision can be compromised. The clearer the night, the farther one will be able to see with night vision technology. It should also be noted that night vision shouldn't be magnified, as light is lost during the magnification process making it more difficult to see.

Night vision devices include: - Cameras - Binoculars - Scopes for firearms - Goggles

If you think that using a night vision device on a frequent basis might be harmful, you couldn't be more wrong. Night vision products are no more harmful than a television or movie screen. It doesn't emit radiation or other harmful rays and there's no reason for it to cause blindness.


About the Author
James Hunt has spent 15 years as a professional writer and researcher covering stories that cover a whole spectrum of interest. Read more at www.night-vision-central.info