Night vision goggles may bring to mind action movies or video games, but they are a real technology operating on scientific principles. Although often used by military organizations, night vision goggles are available to civilians. With these optical devices, a wearer can see up to 200 ft (60.9 m) away on a moonless, cloudy night.
Night vision goggles use one of two methods to enhance sight. Image enhancement concentrates particles of light too small or too low in the color spectrum for a human to pick up on. One of the benefits to image enhancement is that it allows easy identification of a target, which thermal imaging may not. Thermal imaging is able to capture the heat of an object, which appears as bright colors, the warmer it is. Thermal imaging is useful if you are looking for humans or animals, as non-breathing material such as trees and rocks does not show up very well.
The green tint that night vision images appear in is a result of image enhancement technology. As the images pass through the lenses of the night vision goggles, they reach a screen coated in phosphors, which glow when activated by electrons. These phosphors are intentionally tinted green, as the human eye can identify and differentiate between green shades better than any other color.
The first night vision goggles were invented by the United States Army for use in World War II and the Korean War. The Nazi forces invented a similar technology, but it was used mainly as a tank accessory while the American device was used by snipers. Later versions of the goggles eliminated the need for an infrared illumination source, able to use ambient light instead. The current generation of army-issue goggles is highly advanced, able to magnify light 30,000-50,000 times.
The US Air Force has recently conducted experiments with panoramic night vision goggles, increasing the pilot’s field of view to 95 degrees. Several new experimental devices combine thermal imaging with image enhancement, in an attempt to increase visibility of targets. Some companies have also recently premiered digital night vision with zoom capabilities.
Night vision effects are a favorite device in filmmaking, and frequently appear in movies for their traditional use as military or sniper aids, or for comic effect. Several lists exist on the internet of the various uses of the technology in films. Popular examples include Patriot Games, Cats and Dogs, Black Hawk Down, and Sixteen Candles.
Some countries have laws dictating what form of night vision goggles are allowed for commercial civilian use. Be sure to check the relevant laws in your own country before purchasing night vision equipment. Prices vary widely, depending on the generation of technology used in the goggles. A simple monocular night vision device can cost between $150-$200 US Dollars (USD.) The most advanced binocular versions are quite expensive and can exceed $10,000 USD.