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| Night vision devices gather existing ambient light
(starlight, moonlight or infra-red light) through the front lens. This
light, which is made up of photons goes into a photocathode tube that
changes the photons to electrons. The electrons are then amplified to a
much greater number through an electrical and chemical process. The
electrons are then hurled against a phosphorus screen that changes the
amplified electrons back into visible light that you see through the
eyepiece. The image will now be a clear green-hued amplified re-creation
of the scene you were observing. |
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| A Night Vision Device can be either a 1st, 2nd, 3rd
or 4th generation unit. What this stands for is what type of light
intensifier tube is used for that particular device The light
intensifier tube is the heart and soul of an NVD. |
1st generation is currently the most popular type of night vision
in the world. Utilizing the basic principles described earlier, a 1st
generation will amplify the existing light several thousand times
letting you clearly see in the dark. These units provide a bright and
sharp image at a low cost, which is perfect, whether you are boating,
observing wildlife, or providing security for your home. You may notice
the following when you are looking through a 1st gen unit
- A slight high-pitched whine when the unit is on.
- The image you see may be slightly blurry around the edges. This is
known as Geometric Distortion.
- When you turn a 1st gen off it may glow green for some time.
- These are inherent characteristics of a 1st gen and are normal.
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2nd generation is primarily used by law enforcement or for
professional applications. This is because the cost of a 2nd gen unit is
approximately $500.00 to $1000.00 more then a 1st gen. The main
difference between a 1st and a 2nd generation unit is the addition of a
micro-channel plate, commonly referred to as a MCP. The MCP works as an
electron amplifier and is placed directly behind the photocathode. The
MCP consists of millions of short parallel glass tubes. When the
electrons pass through these short tubes, thousands more electrons are
released. This extra process allows 2nd generation units to amplify the
light many more times then 1st generation giving you a brighter and
sharper image. |
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3rd generation By adding a sensitive chemical, gallium arsenide
to the photocathode a brighter and sharper image was achieved over 2nd
generation. An ion barrier film was also added to increase tube life.
Gen. 3 provides the user with good to excellent low light performance. |
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4th Generation / Gated Filmless tubes:
4th generation / Gated Filmless technology represents the biggest
technological breakthrough in image intensification of the past 10
years. By removing the ion barrier film and "Gating" the system Gen 4
demonstrates substantial increases in target detection range and
resolution, particularly at extremely low light levels. |
The use of filmless technology and auto-gated power supply in 4th
generation image intensifiers result in:
- Up to 100% improvement in photoresponse.
- Superb performance in extremely low light level (better S/N and
EBI)
- At least triple high light level resolution (a minimum of 36 lp/mm
compared to 12 lp/mm)
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| With significant improvement in contrast level and in performance
under all light conditions, 4th generation represents the top of the
line performance in the night vision market. Note: The term 4th
generation is used/accepted among Night Vision manufactures to describe
gated filmless tubes. However, this designation is widely debated and is
currently referred to as Filmless & Gated image intensifiers by the US
Military. |
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Gen 4 technology improves night operational effectiveness for
military users of night vision goggles and other night vision
devices. The filmless MCP provides a higher signal-to-noise ratio
than Gen 3, resulting in better image quality (less scintillation)
under low-light conditions. The gated power supply further improves
image resolution under high light conditions, and the reduced halo
minimizes interference from bright light sources. These improvements
also substantially increase the detection range of the systems. |
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Gen 3
Omni IV |
Gen 4 |
%
Improvement |
| Photoresponse (µA/Im) |
1800 |
1800 |
- |
| Signal-to-Noise Ratio |
21.0 |
25.0(ground) |
20% Higher |
| 26.0(air) |
24% Higher |
| Resolution(lp/mm) |
64 |
64 |
- |
| Halo(mm) |
1.25 |
0.75 |
40% smaller |
| Reliability(hours) |
10,000 |
10,000 |
- |
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RANGE IMPROVEMENT
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| Relative direction ranges |
| PVS-7 System |
| Overcast Starlight Conditions (-1x10E-5 tc) |
| Vehicle Size Target, 30% Contrast |
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Gen 2 |
SuperGen 2 |
Gen 3 OMNI
I and II |
Gen 3 OMNI
III |
Gen 3 OMNI
IV |
Gen IV |
| Detection Range (m) |
170 |
270 |
240 |
290 |
360 |
430 |
% Improvement
over Gen II |
0% |
60% |
40% |
70% |
110% |
153% |
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| Gen IV technology is not currently available
for export. |
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All Starlight scopes need some light to amplify. This means that if you
were in complete darkness you could not see. Due to this we have a built
in infra-red illuminator (IRI) on all of our scopes. Basically what an
IRI does is throw out a beam of infra-red light that is near invisible
to the naked eye but your NVD can see it. This allows you to use your
scope even in total darkness. The IRI works like a flashlight and the
distance you can see with it will be limited. We do use the most
powerful eye-safe illuminator on the market. This allows our IRI to
extend out to 100 yards However, because of the power at a short
distance the IRI may cover only 40-60% of the viewing area. |
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There are many different variables that can effect the distance that you
can see with a Night Vision device. First, what are you trying to see?
Are you looking for another boat on the water or are you looking for a
rabbit in the woods? The larger the object the easier it is too see.
Plus, are you trying to see details (what we call recognition range) or
are you just trying to see if something is there or maybe you will just
see movement but won't be able to 100% determine who or what it is. This
is called detection range. Second. Another variable is lighting
conditions. The more ambient light you have (starlight, moonlight,
infrared light) the better and further you will be able to see You can
always see further on a night where the moon and stars are out then if
it is cloudy and overcast. We typically state that you can tell the
difference between a male and a female or a dog and a deer at about 75
to 100 yards. However, if you were looking across an open field and
there was a half moon out you could see a barn or a house 500 yards
away.
Remember, that the purpose of an NVD is to see in the dark not
necessarily a long ways like a binocular. |
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As you look through a night vision device you may notice black spots on
the screen. A NVD is similar to a television screen and attracts dust
and dirt. Typically these spots can be cleaned. However, this may also
be a spot in the tube itself. This is normal. Most tubes will have some
spots in them. These black spots will not affect the performance or
reliability of the night vision device. |
