When the term 'Night Vision" is used, it normally refers to the capacity of various
viewing instruments to provide you with some clarity of vision when viewing objects
in moonlit conditions or total darkness. The technology has been used in binoculars,
goggles, monoculars and various other scopes.
The website, How Stuff Works, has a very useful guide to the analysis of Night
Vision technology.
"In order to understand night vision, it is important to understand something about light. The amount of energy in a light wave is related to its wavelength: Shorter wavelengths have higher energy. Of visible light, violet has the most energy, and red has the least. Just next to the visible light spectrum is the infrared spectrum.
Infrared light is a small part of the light spectrum.
Infrared light can be split into three categories:
* Near-infrared (near-IR) - Closest to visible light, near-IR has wavelengths that range from 0.7 to 1.3 microns, or 700 billionths to 1,300 billionths of a meter.
* Mid-infrared (mid-IR) - Mid-IR has wavelengths ranging from 1.3 to 3 microns. Both near-IR and mid-IR are used by a variety of electronic devices, including remote controls.
* Thermal-infrared (thermal-IR) - Occupying the largest part of the infrared spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30 microns.
The key difference between thermal-IR and the other two is that thermal-IR is emitted by an object instead of reflected off it. Infrared light is emitted by an object because of what is happening at the atomic level."
Read.
The New Scientist Magazine reported on a significant improvement in Night Vision technology
which was spearheaded by the Dutch military early this year.
"A REVOLUTIONARY night-vision system developed for the Dutch military makes night-time video images look as clear and colourful as those shot in broad daylight.
Full-colour night vision would help emergency services and the military better assess their surroundings, says Alex Toet of the TNO research lab in Soesterberg, the Netherlands, who led the team that developed the system. He says it will make it easier to judge distances, enhancing "situational awareness".
Today's night-vision cameras brighten dim images using circuitry that amplifies what little light there is. An alternative technology, which can be used in total darkness, uses infrared sensors to map the heat radiation that emanates from all objects.
But the detectors in night-vision cameras only pick up a limited range of wavelengths, so do not give enough information to generate a colour image, while thermal imaging cameras pick up no colour information at all. In both systems, the image is displayed in various intensities of green or grey, the colours people find easiest to see."
Read.
Sources: How Stuff Works: New Scientist
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