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How Does Night Vision Work?

All Generation 3 Night Vision products we sell are powered by new ITT Industries Night Vision image intensifier tubes (IIT).  The image intensifier tube is the most important part of a night vision device.  ITT is the largest manufacturer of high-quality, high-performance night vision image intensifier tubes. 

 

How does night vision work? There are two major types of night vision technologylight amplification (or intensification) and thermal (infrared).

 

Most night vision products including the most common consumer devices are light amplifying.  Light amplification takes whatever small amounts of light are available such as moonlight or starlight, and converts the light energy (photons) into electrical energy (electrons).

 

Light amplification devices pass these electrons through a thin disk about 2.5mm diameter, containing more than 10 million channels. When the electrons pass through these channels and strike the channel walls, thousands more electrons are released. The multiplied electrons then bounce off of a phosphor screen that converts the electrons back into photons, allowing you to see an impressive nighttime view even on the darkest nights.

 

How Night Vision Works (Video)

 


Differences in Night Vision Technology

Generation (Gen) 3 is the most sophisticated night vision technology available. The photocathode is coated with sensitive gallium arsenide that allows for a more efficient conversion of light to electrical energy at extremely low levels of light.  Gen 3 provides the clearest, sharpest night vision image available. These units have a high-performance image intensifier tube with a minimum 51 lp/mm resolution (typical 64 lp/mm), compared to the 45 lp/mm minimum of a standard Generation 2 unit. Line Pairs per Millimeter (lp/mm) are units used to measure image intensifier resolution; the higher they are, the clearer the image becomes.

 

Generation 2 marked the development of a microchannel plate that multiplied the number of electrons by thousands. This produced a clear image in nighttime situations without the distortion found in Gen 0 and Gen 1.

 

Generation 1 had problems with distortion and short-lived intensifier tubes. It used materials that were better than Gen 0 to convert light to electrons. These units were able to operate at lower light levels than the Gen 0 and became known as "starlight scopes." Imported night vision viewers usually use Gen 1 image intensifiers even though they may be advertised as Gen 2.

 

Generation 0 technology depended on external light to increase available light energy.  After the light was converted to electrons, electrical components filtered these electrons through a cone-shaped device (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. Most Generation 2 products are controlled by the U.S. Department of Commerce, Bureau of Export Administration, Commodity List Number 6A002.

 

Performance Attributes

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. ITT'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 an acceptable performance under low-light conditions.

 

Signal to Noise ratio plays a key role in night vision performance. ITT's 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, ITT Night Vision gives you a quality output image without "noise."

 

Resolution is the third major consideration when purchasing night vision products. This is the ability to resolve the detail in your image. High-quality optics and the latest processing methods give ITT Night Vision the edge. Some of our competitors put magnified optics in their systems to give the illusion that they have high-resolving systems. As a trade-off, the field of view is sacrificed. ITT gives the option of higher magnification only, so you can have it only if you want it. The system 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.

 

ITT Night Vision provides you with the best night vision performance on the market. That's because we have highly trained engineers dedicated to continuous process improvement in the state-of-the-art development of night vision image tubes and systems. We are the world's leader for Gen 3 image intensified (amplified) 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.  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
Through a night vision unit, objects that appear light during the day but have a dull surface may appear darker 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.

 

Depth Perception
Night vision does not present normal depth perception.

 

Fog and Rain
Night vision is very responsive to reflective ambient light.  Therefore, 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 that is the result of the manufacturing process.

 

Spots*
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.  See the example below of an image with black spots.

 

 

* Do not be concerned if you see this.  It is an inherent characteristic found in all light amplification night vision systems that incorporate a microchannel plate in the intensifer.