Night vision is becoming more and more common for a variety of applications. The drastic improvements in night vision technology over the past decade has made the products available today some of the most important equipment available to military and law enforcement…but how does it work? Night Vision Devices consist of several main parts: an objective lens, an eyepiece, a power supply and an image intensifier tube (Photocathode Tube). 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.
Technical Characteristics of Night Vision:
Using intensified night vision is different from using regular binoculars and/or your own eyes. Below are some of the aspects of night vision that you should be aware of when you are using an image intensified night vision system:
- Textures, Light and dark objects that appear light during the day but have a dull surface may appear darker through the night vision unit than objects that are dark during the day but have a highly reflective surface. For example, a shiny dark colored jacket may appear brighter than a light colored jacket with a dull surface.
- Night vision does not present normal depth perception. Fog and Rain Night vision is very responsive to reflective ambient light; therefore, the light reflecting off of fog or heavy rain causes much more light to go toward the night vision unit and may degrade its performance.
- A few black spots throughout the image area also are inherent characteristics of all night vision technology. These spots will remain constant and should not increase in size or number. Do not be concerned if you see this – It is an inherent characteristic found in light amplification night vision systems that incorporate a microchannel plate in the intensifer.