How Night Vision Works
There are two major types of night vision technology: image intensification (light amplification) and thermal (infrared).
All Exelis Night Vision products use light-amplifying technology. This technology takes the small amount of light available in the surrounding area, known as ambient light (such as moonlight or starlight), and converts the light energy (called photons) into electrical energy (electrons).
These electrons pass through a thin disk about the size of a quarter that contains more than 10 million channels. As the electrons travel through the channels, they strike the channel walls, which produces thousands more electrons. These multiplied electrons then bounce off of a phosphor screen which converts the electrons back into photons and lets the user see an impressive nighttime view, even when it's nearly pitch-dark.
Differences in Night Vision Technology
Generation (Gen) 3 technology is the most sophisticated night vision technology available. The photocathode is coated with sensitive gallium arsenide, which allows for a more efficient conversion of light to electrical energy at extremely low levels of light.
Generation 3 provides the clearest, sharpest night vision image available. Line pairs per millimeter (lp/mm) are units used to measure image intensifier resolution; the higher they are, the clearer the image becomes. Gen 3 units have a higher-performing image intensifier tube with a minimum 57 lp/mm resolution, compared to the 45 lp/mm minimum of a standard Gen 2 unit.
Generation 2 technology marked the development of a microchannel plate, which multiplies the number of electrons by the thousands. This produces a clear image in nighttime situations without the distortion seen in Gen 0 and Gen 1 technology.
Generation 0 technology depended on external light to increase available light energy. After the light was converted to electrons, electrical components focused these electrons through a cone-shaped device (called an anode) and accelerated them so they hit the phosphor screen with greater energy, creating the visible image. Unfortunately, accelerating the electrons in this manner caused distortion in the image and decreased the tube's life.
All Generation 3 products sold internationally require an export license from the U.S. Department of State, Office of Defense Trade Controls, in accordance with International Traffic in Arms (ITAR), Title 22, Code of Federal Regulation.
There are three important attributes for judging performance. They are: sensitivity, signal 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 "uA/lm," or microamperes per lumen. Exelis Night Vision's advanced technology and processing enable us to give our customers products with outstanding sensitivity. That's why many of our products do not come with standard IR illuminators. With many applications, illuminators are not necessary. Our competitors put IR illuminators on their products to obtain acceptable performance in low-light conditions.
Signal plays a key role in night vision performance. Our microchannel plate technology is unsurpassed in its ability to transfer a strong signal from input to output. Just as high-end stereo equipment gives you quality sound, Exelis gives you a quality output image without "noise."
Resolution is the third major consideration when purchasing night vision. This is the ability to resolve detail in your image. High-quality optics and the latest processing methods give Exelis Night Vision the edge. Some of our competitors put magnified optics in their systems to give the illusion that they have high-resolving systems. The trade-off with this solution is that field-of-view is sacrificed. Exelis offers the option of higher magnification only so you can have it if you want it, however, our night vision does not need higher magnification to function effectively. Our technology offers a uniquely formulated phosphor screen to create the highest contrasting images, thereby generating the highest resolution products available to the consumer.
Exelis Night Vision provides users with the best night vision performance on the market. We have highly trained engineers dedicated to continuous process improvement in state-of-the-art development of night vision image tubes and systems. We are the world's leading manufacturer of Gen 3 image intensified night vision products for the U.S. military. Ensuring that our military remains the best in the world requires excellence in product and technology development, and we pass that excellence on to all our customers. You get the latest technology and the assurance that our products meet or exceed all others on the market.
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. However, advances in the latest night vision help offset these effects.
Honeycomb is a faint hexagonal pattern, which is the result of the manufacturing process.
A few black spots throughout the image area also are inherent characteristics of all night vision technology. These spots will not increase in size or number.
* 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 intensifier.