1. How Does Night Vision Work
Night vision devices gather existing ambient light (starlight, moonlight or infra-red light) through the front lens. This light, which is made up of photons goes into a photocathode tube that changes the photons to electrons. The electrons are then amplified to a much greater number through an electrical and chemical process. The electrons are then hurled against a phosphorus screen that changes the amplified electrons back into visible light that you see through the eyepiece. The image will now be a clear green-hued amplified re-creation of the scene you were observing.
2. Why is night vision green?
Night Vision is deliberately green in color as shading levels in green are the easiest for the human eye to distinguish. Night Vision used to also be available in red, but scientists later determined that green was easier to see and use.
Can Generation 1 be useful?
Yes, Generation 1 can be useful in most nighttime situations. Newer Generation 1 devices do offer increased performance from there older predecessors. Generation 1 units typically use an S-20 photocathode and electrostatic inversion to achieve gain. They can offer substantial resolution toward the center of the image tube, while the edges may be blurred. Generation 1 devices are usually inexpensive and can be a good start for the night vision enthusiast.
4. What is the effective viewing range of a Night Vision Device?
It varies anywhere from 20 to 800 m. The viewing distance depends on the area, conditions and a size of your target. Overcast conditions, fog, rain and snow will significantly reduce the effective viewing range. On the other hand your viewing range will increase dramatically under clear skies and/or full moon. Light reflective surfaces such as snow or sand will also increase the effective viewing range of your night vision device. Infrared illuminator (IR) may help, especially in enclosed environments.
5. Can I use night vision in complete darkness?
Though it is true that night vision devices require little light, it is possible to use them in complete darkness with help of an IR Illuminator. Since most of the time you encounter complete darkness in enclosed environments, high magnification power is not a necessity, you'd rather be able to see at a very close range. In this case the most effective viewing device are goggles. Most goggles have magnification power of 1, built-in IR Illuminator, close focus and a viewing range of a few hundred feet.