Night Vision - Optics And Goggles

Written by Stacy Chbosky
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Night vision devices allow you to go boating beneath a starry sky, hunt in the darkness, or protect your home and loved ones in the wee hours of the night. Although night vision equipment has been around since the 1960s, the technology that powers it has been improving all the time. These improvements have led to a coding system for NV optics, dividing them into different "generations."

In the 1960s, night vision devices were all what we would now call "Generation 1," or "Gen 1." Gen. 1 NV devices work in the same basic way that Gen. 2 and Gen. 3 devices work, but they aren't as powerful or as effective. However, Gen. 1 scopes, goggles and monoculars are relatively inexpensive, which explains their tremendous, continuing popularity.

Generation 2 and Generation 3 Night Vision Devices

Night vision glasses, scopes and other devices are now available in Generations 1, 2, and 3. There are even devices commonly known as "Generation 4," but the U.S. military doesn't officially sanction this vernacular. The military refers to Gen. 4 devices as Filmless and Gated image intensifiers.

All night vision devices work in fundamentally the same way. They all rely on four basic components. Each NV device uses a lens, a tube, an eye piece, and a power supply. In other words, each NV scope or monocular has something that lets the light in, something to act upon that light and change it, some way to view the changed light, and power to make the whole process possible.

Let's concentrate on the first of these four components: the lens. The lens is what is known as an objective lens. It gathers light. Light is rather an amazing thing. Not all light, for instance, is visible to the human eye. Light comes in different wavelengths. The lens gathers available light (ambient light) of all different wavelengths and varieties, including infrared, starlight, moonlight, and distant man-made light.

The Heart of the Night Vision World

This light is then focused on the very heart of the night vision device and the instrument that makes all NV products possible: the tube. This tube is known as an image intensifier tube. It takes all those photons (from the available light) and, in turn, emits electrons. These electrons are then dramatically multiplied, with the help of the power source.

These speedy electrons hurl themselves against a green phosphor screen. This creates an image. The image can be improved with the adjustment of the eyepiece. Resolution varies widely depending on the generation of night visionwear being used, and the amount of ambient light.

But why is the image green? Green was made the default screen color for a number of reasons. First, human eyes are able to pick up many variations within shades of green. Our eyes are sensitive to green. Second, green is easy on the eyes. It reduces eye strain and fatigue.

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