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.
1. Front Lens
4. Power Supply
2. Photocathode
5. Phosphorus Screen
3. Microchannel plate
6. Eyepiece
FIRST, SECOND,
THIRD AND FOURTH GENERATION
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.
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 index 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.
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.
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)
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.
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.
Gen 3 Omni IV
Gen 4
% Improvement
Photoresponse (зA/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
-
RANGE
IMPROVEMENT
Relative direction
ranges
PVS-7 System
Overcast Starlight Conditions
(-1x10E-5 tc)
Vehicle Size Target, 30%
Contrast
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%
Gen IV technology is not
currently available for export.
XD-4 Image Intensifiers
The XD-4 is the top grade of
the DEP Image Intensifiers. With the
introduction of the XD-4 technology a new
European Standard for low light imaging was born
providing unprecedented performance in Night
Vision applications.
The XD-4 Image Intensifiers
perform extremely well in all environmental
conditions. Its wide spectral sensitivity range
ensures that a perfect picture is obtained
regardless of the user's environment (foliage,
on water, snow, desert, rocky and barren land)
or light conditions (down to heavily overcast
starlight). The XD-4 Image Intensifiers
provide as well a superb image under very
dynamic light conditions.
The basis for the unique
performance of the XD-4 is the technology used
by DEP. This has resulted in greatly improved
performance parameters that are crucial for good
observation, such as the Signal-to-Noise Ratio
(SNR), the Modulation Transfer Function (MTF)
and Resolution under all circumstances. Add to
this the very long lifetime throughout its
complete luminance dynamic range and you will be
convinced of its unique performance.
The performance parameters of
the XD-4 Image Intensifier are listed in the
table below. Highlights of the XD-4
specification are the typical SNR of 24, the
resolution of 64 lp/mm and over and - very
important - the high MTF at low and intermediate
spatial frequencies. The latter gives the image
its sharpness and contrast.
It goes without saying that
the XD-4 tubes can be supplied in every common
mechanical construction including inverting and
non-inverting fibre-optic output, which also
means that users have the opportunity to upgrade
the performance of existing Night Vision
Equipment via a drop-in XD-4 Image Intensifier.
Technical specifications of
XD-4 technology image intensifiers:
Resolution
Minimal
Typical
Maximal
UNIT
Limiting resolution
Type I
55
58
lp/mm
Type II
60
64
lp/mm
Modulation Transfer
Function:
2.5 lp/mm
92
%
7.5 lp/mm
80
%
15 lp/mm
58
%
25 lp/mm
38
%
30 lp/mm
30
%
Signal to Noise
Minimal
Typical
Maximal
UNIT
Signal to noise (@108зlx)
20
24
Other Technical Data
Minimal
Typical
Maximal
UNIT
Phosphor: P20*
MTTF (to S/N=12)
15.000
hrs
Gain at 2.10-5 lx
30.000/p
50.000/p
cd/m2/lx
Max. Output Brightness
2
17
cd/m2/lx
E.B.I.
0.15
0.25
lx
Output uniformity at 2850K
2:01
3:01
Weight(18mm)
80
95
grams
Shock
500
g
Luminous sensitivity at
2850K
600
700
uA/lm
Radiant sensitivity at
800nm
50
60
mA/W
Radiant sensitivity at
850nm
40
50
mA/W
DEP Image
Intensifiers with XR-5 Technology
As a result of sustained and
continuing product development, DEP is proud to
introduce the latest, innovative XR5 Image
Intensifier with unprecedented performance for
any environment and any circumstance.
The XR5 Image Intensifier,
successor to the well-known and successful XD-4
Image Intensifier, reveals even more details of
the night and offers an eXtended Range (XR)
capability thanks to its new technology.
Furthermore, the XR5 Image
Intensifier enables the user to see even more
during a full 24-hour day/night operation. This
is done by the use of a fully integrated
Auto-Gating unit, which controls the image not
only during day-night-day transitions but also
during dynamic lighting conditions such as those
experienced, for example, in night operations in
urban areas. In practice, this means no blooming
to hinder your mission but dependable imagery
throughout. In addition, the halo is the
smallest on the market.
The XR5 Image Intensifier from
DEP represents the new European standard for
Night Vision and is available in a variety of
inverting and non-inverting 18 mm formats.
The new XR5 is your best choice to
indextain your combat effectiveness under all
circumstances.
Technical specifications
of XR5 technology image intensifiers:
Resolution
Minimal
Typical
Maximal
UNIT
Limiting resolution
64
70
lp/mm
Modulation Transfer
Function:
2.5 lp/mm
93
%
7.5 lp/mm
82
%
15 lp/mm
67
%
25 lp/mm
46
%
30 lp/mm
35
%
Signal to Noise
Minimal
Typical
Maximal
UNIT
Signal to noise (@108зlx)
25
28
Luminance dynamic range
Minimal
Typical
Maximal
UNIT
Auto-Gating and Automatic
Brightness Control
1.0E-06
5.0E+04
lux
Other Technical Data
Minimal
Typical
Maximal
UNIT
Phosphor: P20*
Reliability
15.000
hrs
Gain at 2E-05 lux
30.000/p
50.000/p
cd/m2/lx
Max. Output Brightness
2
17
cd/m2
E.B.I.
0.25
ulx
Luminous sensitivity at
2850K
700
800
uA/lm
Radiant sensitivity at
800nm
65
78
mA/W
Radiant sensitivity at
850nm
50
65
mA/W
Input voltage
2
3.7
volt
Input current
35
mA
Output uniformity at 2850K
1.8:1
3:01
Weight (18mm)
80
95
g
Shock
500
g
INFRA-RED
ILUMINATORS
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.
HOW FAR CAN YOU
SEE
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.
BLACK SPOTS ON THE
SCREEN
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.
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.
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.
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.
Night Vision Scopes Binoculars &
Goggles Index