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HOW NIGHT VISION WORKS
GENERAL OVERVIEW: Most consumer night vision products are light amplifying devices. Light amplification is less expensive than thermal, however, higher-end and more effective night vision tubes can become more expensive. Light amplification technology takes the small amount of light, such as moonlight or starlight, that is in the surrounding area, and converts the light energy (scientists call it photons), into electrical energy (electrons). These electrons pass through a thin disk that's about the size of a quarter and contains over 10 million channels. As the electrons travel through and strike the walls of the channels, thousands more electrons are released. These multiplied electrons then bounce off of a phosphor screen which converts the electrons back into photons and lets you see an impressive nighttime view even when it's really dark.
In the night vision world there are generations that reflect the level of technology used. The higher the generation, the more sophisticated the night vision technology.
When discussing night vision technology, you also may hear the term "Omnibus" or "OMNI". The U.S. Army procures night vision devices through multi-year/multi-product contracts referred to as "Omnibus" - abbreviated as "OMNI". For each successive OMNI contract, ITT has provided Gen 3 devices with increasingly higher performance. ( See range detection chart directly below) Therefore, Gen 3 devices may be further defined as OMNI 3, 4, 5, etc. Current Omnibus contract as of 2006 is OMNI 7.
If you're using night vision to find a lost person in the woods, to locate boats or buoys on the water, or to stargaze into the wilderness, you need Generation 3 because it creates the best images when there is very little ambient light. Generation 2 may be the choice in situations with higher levels of ambient light. KEY GENERATION DEVELOPMENTS:
Beyond
outperforming all previous technologies, corresponding improvements
in reliability have been equally dramatic. GEN III intensifiers
have a useful operating life of 10,000+ hours, making tube replacement
virtually unnecessary. The intensifier tube normally represents
75% of the overall system cost.
Performance Attributes There are three important
attributes for judging performance. They are: sensitivity, signal-to-noise,
and resolution. As the customer, you need to know about these three
characteristics to determine the performance level of a night vision
system.
Sensitivity, or photoresponse,
is the image tube's ability to detect available light. It is usually
measured in "µA/lm," or microamperes per lumen.
That's why many of our products do not come with standard IR illuminators.
With many applications illuminators aren't necessary. Some manufacturers
put IR illuminators on their products in order to get acceptable
performance under low light conditions.
Signal-to-noise
plays a key role in night vision performance. A microchannel plate
used to transfer a signal from input to output. Just as high-end
stereo equipment gives you quality sound.
Resolution
is the third major consideration when purchasing night vision. This
is the ability to resolve detail in your image. Some manufacturers
put magnified optics in their systems to give the illusion that
they have high resolving systems. In the trade-off, field of view
is sacrificed. Some models give the option of higher magnification
so you can have it if you want it, not because your system needs
it to function effectively. Most of Morovision's products offer
a uniquely formulated phosphor to create the highest contrasting
images, therefore generating the highest resolution products available
to the consumer.
Distance and Magnification Charts:
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. See also: Night Vision Terminology; How to Buy Night Vision; How Thermal Vision Technology Works. 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 shiney dark colored jacket may appear brighter than a light colored jacket with a dull surface. Depth Perception
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. Honeycomb*
This is a faint hexagonal pattern which is the result of the manufacturing process. Black Spots*
A few black spots throughout the image area are also inherent characteristics of all night vision technology. These spots will remain constant and should not increase in size or number. See example below of an image with black spots. * Do not be concerned if you see this feature-it is an inherent characteristic found in light amplification night vision systems that incorporate a microchannel plate in the intensifer.
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All
image intensified night vision products on the market today have
one thing in common: they produce a green
output image. Like the one your see to your right - >>.
But that's where the similarities end. 
