Generation 2 - The micro channel plate (MCP) electron multiplier prompted Gen 2 development in the 1970s. The "gain" provided by the MCP eliminated the need for back-to-back tubes - thereby improving size and image quality. The MCP enabled development of hand held and helmet mounted goggles.
Second-generation image intensification significantly increased gain and resolution by employing a microchannel plate. Figure 2 depicts the basic configuration. The microchannel plate is composed of several million microscopic hollow glass channels fused into a disk. Each channel, approximately 0.0125 mm in diameter, is coated with a special semiconductor which easily liberates electrons. A single electron entering a channel initiates an avalanche process of secondary emission, under influence of an applied voltage, freeing hundreds of electrons. These electrons, effectively collimated by the channel, increase the resolution of the device. With additional electron optics, details as fine as 0.025 mm can be realized (half the diameter of a human hair).
Current image intensifiers incorporate their predecessor's resolution with additional light amplification. The multialkali photocathode is replaced with a gallium arsenide photocathode; this extends the wavelength sensitivity of the detector into the near infrared. The moon and stars provide light in these wavelengths, which boosts the effectively available light by approximately 30%, bringing the total gain of the system to
around 30,000.slightgreen tint similar to some sunglasses. The apparent lighting of the landscape on a darknight is comparable to what the unaided eye would see on a clear winter night with freshsnow on the ground and a full moon.
Generation 3 - Two major advancements characterized development of Gen 3 in the late 1970s and early 1980s: the gallium arsenide (GaAs) photocathode and the ion-barrier film on the MCP. The GaAs photocathode enabled detection of objects at greater distances under much darker conditions. The ion-barrier film increased the operational life of the tube from 2000 hours (Gen 2) to 10,000 (Gen 3), as demonstrated by actual testing and not extrapolation.
Generation 4 - for a good explanation of this commonly misunderstood advancement in 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:
• GENERATION 1 (Developed in 1960's);
o Vacuum Tube Technology
o Full Moon Operation
o Amplification: 1,000
o Operating Life: 2,000 Hours
• GENERATION 2 (Developed in 1970's);
o First Micro channel Plate (MCP) Application
o One-Quarter Moon Operation
o Amplification: 20,000
o Operating Life: 2,500 Hours
• GENERATION 2+ (1970s)
o Development increased image tube bias voltage to improve gain.
o Additionally, a glass faceplate was added to improve resolution.
• GENERATION 3 (Developed in 1990's);
o Improved MCP & Photocathode
o Starlight Operation
o Amplification: 40,000
o Operating Life: 10,000 Hour
• GENERATION 4 Enhanced (2000's);
o Improvements in the photocathode and MCP resulted in increased gain
and resolution.
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