What is the Minimal Amount of Light Required to Operate an NVD?
What Can 2nd Generation NVD 's do That 1st Generation NVD 's Cannot?
What type of light source can be harmful to a night vision device?
Night Vision Devices are electronically enhanced optical devices that enable us to see in near-total darkness. At the heart of all night vision systems is an image intensifier, sometimes referred as an image tube or I2 tube. The image tube is what amplifies visible and non-visible light so the human eye can see it. There are several Generations, or Gen's available on the market today. Each generation denotes an improvement in image tube production. In addition to the intensifier tube, a night vision device separated into other components. One component is the optics, which include the objective and eyepiece lenses. The objective lens is the lens closest to the object being viewed and focuses for range. The eyepiece is the lens closest to the eye and is focusable to accommodate users with imperfect vision. Another component of a night vision device is the electronics. All night vision devices require a power supply to operate. Most use 2 AA or 3V Lithium Batteries.
In Generation II and III systems, the night vision devices work similar to video cameras by gathering minute particles of light, called photons, that you cannot see with your naked eye, through the front objective lens. Instead of focusing the image on the film plane or CCD (video chip), the objective lens focuses the image on one end of a Light Intensifier Tube. This light, which is made up of photons goes into a photocathode tube that changes the photons to electrons. The electrons are then amplified and then accelerated past a field-forming electrode to a phosphor-covered screen that changes the amplified electrons back into visible light. The image is inverted and focused by static electricity. The phosphors glow bright green where struck by electrons and the observer looks at the screen through an optical eyepiece(s) and sees the image.
Gen 0 (World War II Technology): Typically uses a S-1 photocathode (with photosensitivity of 60 mA/lm), electrostatic inversion, and electron acceleration to achieve gain. As a result, Gen 0 tubes are characterized by the presence of geometric distortion and the need for active infrared illumination.
Gen 1 (Vietnam
Era Technology) is the
most widely sold type of night vision in the world. Typically uses an S-20
photocathode (with sensitivity of 180-200 mA/lm). Because of higher
photosensitivity, Gen 1 was the first truly passive image intensifier.
Developed in 1960's
Vacuum Tube Technology
Full Moon Operation
Amplification: 1,000
Operating Life: 2,000 hours
Example: Best Quality Russian Night Vision
Gen 2 (Post
Vietnam Technology) The main difference between a 1st and a 2nd
generation unit is the micro-channel plate or MCP. Usually an S-25 photocathode (with photosensitivity of 240+ mA/lm) and
a microchannel plate is used to achieve gain that can be found with either electrostatic or
fiber-optic inversion. The MCP amplifies the electrons and is directly behind
the photocathode. GEN 2 tubes provide satisfactory performance at low light levels
and exhibit low distortion.
Developed in 1970's
1st Microchannel Plate (MCP) Application
One-Quarter Moon Operation
Amplification: 20,000
Operating Life: 2,500 hours
Example: American Eagle Model 502
Gen 3
(Desert Storm Technology) Uses gallium arsenide for the
photocathode and a micro-channel plate for gain, and is also coated with an ion
barrier film to increase tube life. Gen 3 produces more than 800 mA/lm and
provides very good to excellent low light performance and long tube life.
Developed in 1990's
Improved MCP & Photocathode
Starlight Operation
Amplification: 40,000
Operating Life: 10,000+ hours
Example: AN/PVS-7B
Gen 4 (State-of-the-Art Technology) 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. Measured in µA/lm, the number of electrons released by the Photocathode (PC) is always measured in isolation with no amplification stage or ion barrier (film). Therefore, tube data sheets (which always carry this “raw” figure) do not reflect the fact that over 50% of those electrons are lost in the ion barrier. While for most latest 3rd generation image intensifiers the Photo response is in the 1800 µA/lm (2000 µA/lm for the latest Omni VI Pinnacle tubes), the actual number is more like 900 µA/lm. The Gen 4 DOES NOT use ion barrier and while its “raw” Photo response is the same as 3rd, the actual number is actually 100% higher.
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.
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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Generation Comparison
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Any night vision intensifier requires some ambient light to operate effectively. The degree of night illumination necessary is a function of the technology employed. Minimum operating light levels for each Generation is depicted. The distance in meters (m) is the range at which a 6 foot man can be seen. The range of vision is determined by the type of Image tube, number of line pairs, photo-response and many other features that make up the NV device. Typically, a Generation 3 device will be able to detect a man sized target anywhere from 100 yards to over 2,400 yards, depending on the tube and the lighting conditions.
 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. |
The threshold of vision with an NVD can vary with different “generations,” the quality of the devices, distance and the environment. A Gen-1 NVD with 500x amplification will give a very useful image in the dimmest light of a scarcely visible new moon. From 100 feet, you can distinguish between kinds of animals, whether a human figure is familiar, male or female. While the screen images are not as sharp as a photograph, Night Vision Devices are astonishing in what they accomplish. System amplification on the second-generation NVD is 22,000 times!
Two reasons:
1) NVD 's make possible a quality of seeing that is far superior to flashlights. They provide your eyes with a light amplification tool that gives you much more night vision sensitivity than many nocturnal animals.
2) See, without being seen. Think of the advantages of seeing without intruding when you are trying to find your way around an unlit campground. Property owners can observe nocturnal criminal activity. Hunters and nature lovers can observe animals without startling them. If you suspect a prowler is nearby, you can spot the “perpetrator” without alarming him and safely call the police.
Yes, if there is no light to amplify, there can be no image. A night vision device cannot work in total darkness, but many have a built-in light source (IR illuminator or IR Spotlight) to project a small amount of virtually invisible infrared light onto the subject.
Do you Need a License to use an NVD?
No license is required, but they are valuable to security and rescue occupations such as police, fire, private investigators, security guards, harbor patrols etc. Firemen can find trapped victims in dark buildings. You will however need an Export License to remove Generation 2 and above NV devices from the United States.
Do all NVD 's have IR Illuminators?
Many of the Generation 3 units have them built in, however not all come equipped with them. You can compensate for this by using IR spot/flood lights to illuminate large areas (only seen with Night Vision). Some units allow optional IR illuminators to be attached.
What is the Range of the IR illuminator
This varies with the model and conditions. The low-energy IR illuminators are effective up to more than 100’, and very effective at less than 30’. Typically, most operate around 100mw to 450 mw(milliwatt) range.
Are NVD 's Complex, or Difficult to Use?
They are easier to operate than a video camera. One difference is that you must first focus your eyepiece on the internal screen, then focus the lens on the subject. This simple adjustment takes about five seconds.
Night air conditions frequently include fog and high humidity. NVD 's can sustain damage from constant humidity or immersion. Avoid getting them wet, wipe them off with a soft dry towel after use, and store them in dry place without temperature extremes. Demist shields can be used to minimize the effects of moisture in the air.
Is the NVD Image as Sharp as a Camera Image?
No, the image the user sees is on a glowing phosphor screen, but even “0” generation units can give very useful resolution. All first-generation units produce very recognizable facial features and detail superior to units used by the U.S. Armed Forces in the Vietnam War. Second-generation units improve resolution by about 20% over first-generation units. Third and fourth generation devices provide the greatest resolution and the sharpest picture available today.
What Can 2nd Generation NVD 's do That 1st Generation NVD 's Cannot?
They have about 45 times more light amplification and, as stated above, they produce about 20% better resolution. The great price difference between the two generations is hard for most consumers to justify, but it is a result of the addition of a porous, coated glass screen called a “microchannel plate.” Under most circumstance, there is little practical difference in results between second-generation and first-generation units of equal quality.
What About Third- and Fourth-Generation NVD 's?
They are expensive. The Gallium Arsenide semiconductor material used in third-generation photo cathodes and microchannel plates is very costly.
Technically speaking, there is no such thing as a "Fourth-Generation" classification of night vision devices. There is no "official" Gen 4, because the technology has not yet advanced to the status of a Gen 4 tube, according to the US Army. When this new technology was first introduced, the fourth Generation classification was given and several thousand tubes were sold under this label. These new tubes are currently referred to as "Film less & Gated" image intensifiers. Armada International published an article that covers this widely debated classification in depth.
Can I see in Color With my NVD?
No, all NVD 's are monochromatic. The phosphor screen glows with a green color to take advantage of the human eye’s heightened sensitivity to green.
What type of light source can be harmful to a night vision device?
Your night vision device is designed
to assist your viewing in the dark. It may be harmful and will likely damage the
device if you use it during the daytime or whenever there is sufficient light to
see the object. Also, keep in mind that strong direct light, such as projectors,
car headlamps, strong flashlights and so on, may be harmful to your night vision
unit if you direct your device at the source of these intense lights. Most
of the better units incorporate brightness controls to protect the tube from
overexposure to bright light.
Who do I contact
regarding service issues?
Contact the customer service center for your country.
Please refer to our model identification page to determine what parts and services are available for your sight.
What does Aimpoint's
warranty policy look like?
The warranty is limited to the original owner and is not transferable. A copy of the original receipt showing date of purchase must accompany any warranty claim. Warranty period varies by sight model.
Can I buy replacement
parts or accessories for my Aimpoint sight?
Yes, to see a complete list of accessories available for your particular model, please visit Aimpoint's product identification page.
Is it possible to change
the dot size in my sight?
Only the dot's intensity is adjustable.
What do I need to mount
an Aimpoint sight on my gun?
Aimpoint sights can be mounted on virtually any firearm. Please visit Aimpoint's application page to see Aimpoint's selection of mount. If you don't see a mount for your gun listed on that page, please check with a qualified gunsmith.
Will Aimpoint sights
handle the unique recoil generated by a spring piston airgun?
Only CET series Aimpoint sights should be mounted on this type of airgun.
To what distance can the
dot be seen?
The dot is not projected on to the target. It is only seen inside the sight, so the distance to the target does not limit dot visibility.
I have an Aimpoint
CompM2, what kind of NVD (night vision device) would I need?
The CompM2 is designed for optimum compatibility with 3rd Generation NVDs. Generation 1 and 2 also works.
How big is the dot at
100 meters?
| Aimpoint CET series sights feature a 4 MOA dot. |
| MOA stands for "minutes of angle" and 1 MOA = 1"at 100 yards. |
| This means that the dot is about 10cm at 100m, 5cm at 50m and 2,5cm at 25m. |
The dot in my Aimpoint
sight doesn't look round. Is it defective?
If your dot does not appear to be perfectly round, the distortion is probably caused by the way that your eye perceives the dot, rather than by some mechanical defect. Due to differences in the lenses in different individuals' eyes, round objects that subtend areas near 3 minutes of angle may appear distorted in a variety of ways depending on the individual and other environmental influences. Inexpensive red dot sights sometimes have manufacturing defects that can cause the dot to be an odd shape.
A simple test that can be easily performed will allow you to determine the cause of the apparent distortion:
| Turn the sight on and look through as you
normally would. (This test is easiest when the sight is not mounted on a
firearm, but can be performed with the sight mounted as well. Just make sure
that the firearm is unloaded and pointed in a safe direction.) |
| While continuing to look through the sight,
roll the sight on its optical axis. |
| If the dot's irregularities seem to revolve
around the center of the dot like the spokes of a wheel, there is a
mechanical defect causing the distortion. |
| If the dot does not roll with the sight, the distortion is caused in the way your eye perceives the dot. This is not to say that you don't have good vision. You can see clearly and still see a distortion in objects this small. |
This effect is less pronounced in sights with larger dots. More people will
see the dot in a sight with a 10 minute-of-angle dot as being perfectly round
than will be able to see a 3 MOA dot as round.
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