Night vision devices using image intensifier tube technology
require some ambient light to operate. The level of moonlight,
starlight or other ambient light necessary is a function of the
technology employed. The night vision industry has evolved through
three stages, or "Generations," of development. Generation
I technology is obsolete in the US market. We offer products
based on Generation II, II+, III, and III+. Each generation offers
more sensitivity and can operate effectively on less light.
Generation I
Amplification: 1,000x
The early 1960's was witness to the beginning of passive
night vision. Technological improvements included vacuum tight
fused fiber optics for good center resolution and improved gain,
multi-alkali photocathodes and fiber optic input output windows.
GEN I devices lacked the sensitivity and light amplification
necessary to see below full moonlight, and were often staged
or cascaded to improve gain. As a result, GEN I systems were
large and cumbersome, less reliable, and relatively poor low
light imagers. They were also characterized by streaking and
distortion.
Generation II
Amplification: 20,000x
The development
of the Microchannel Plate (MCP) led to the birth of Generation
II devices in the late 1960's and early 1970's. Higher electron
gains were now possible through smaller packaging, and performance
improvements made observation possible down to 1/4 moonlight.
The first proximity focused microchannel plate (MCP) image intensifier
tube was an 18mm used in the original AN/PVS-5 NVG. Generation
II+ provides improved performance over standard Gen II by providing
increased gain at high and low levels. Generation II+ equipment
will provide the best image under full moonlight conditions and
is recommended for urban environments.
Generation III
Amplification: 30,000 - 50,000x
The current state-of-the-art,
the Generation III intensifier multiplies the light gathering
power of the eye or video receptor up to 30,000 times. Requiring
over 460 manufacturing steps, the GEN III intensifier is typically
characterized by a Gallium Arsenide (GaAs) photocathode, which
is grown using a metal organic vapor-phase epitaxy (MOVPE) process.
The photon sensitivity of the GaAs phtocathode extends into the
near-infrared region, where night sky illuminance and contrast
ratios are highest. Sealed to an input window which minimizes
veiling glare, the photocathode generates an electron current
which is proximity focused onto a phosphor screen, where the
electron energy is converted into green light which can then
be relayed to the eye or sensor through an output window.
The development
of the Microchannel Plate (MCP) led to the birth of Generation
II devices in the late 1960's and early 1970's. Higher electron
gains were now possible through smaller packaging, and performance
improvements made observation possible down to 1/4 moonlight.
The first proximity focused microchannel plate (MCP) image intensifier
tube was an 18mm used in the original AN/PVS-5 NVG. Generation
II+ provides improved performance over standard Gen II by providing
increased gain at high and low levels. Generation II+ equipment
will provide the best image under full moonlight conditions and
is recommended for urban environments.
The current state-of-the-art,
the Generation III intensifier multiplies the light gathering
power of the eye or video receptor up to 30,000 times. Requiring
over 460 manufacturing steps, the GEN III intensifier is typically
characterized by a Gallium Arsenide (GaAs) photocathode, which
is grown using a metal organic vapor-phase epitaxy (MOVPE) process.
The photon sensitivity of the GaAs phtocathode extends into the
near-infrared region, where night sky illuminance and contrast
ratios are highest. Sealed to an input window which minimizes
veiling glare, the photocathode generates an electron current
which is proximity focused onto a phosphor screen, where the
electron energy is converted into green light which can then
be relayed to the eye or sensor through an output window.