Technical FAQs (Frequently Asked Questions)1 - How does night vision work?
2 - What do the terms "Gen1+, Gen2+ and Gen3" mean?
3 - What performance should I expect from Gen1+, Gen2+ and Gen3?
4 - Is night vision legal? Is it safe to use?
5 - What about the export of night vision? Is that possible?
6 - How do I focus my night vision unit?
7 - Which are best? Scopes, binoculars or goggles?
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1 - How does night vision work?
All night vision products work pretty much the same way - they turn light that isn't visible to our eyes into something we can see. Here's a quick description of how it's done...Light from all bandwidths - from barely visible to completely invisible - is gathered by the front objective lens. The lens functions to focus this stream of invisible light into the heart of your night vision device, the image tube. Though image tubes have been refined and improved over the years - from Gen1 to Gen3 and beyond - they all contain an electrically charged screen that produces visible light when the invisible light stream collides with it.
Similar to the phosphorescent screens that are found in tubed televisions, every time an energy particle hits them, they glow. The result of all this smashing and crashing is what you see when you look into your night vision unit - a beautiful, monochrome green image.
What's really intriguing about all this is that no matter how dark it is, there's usually plenty of available light. You just can't see it - unless you've got night vision of course!
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2 - What do the terms "Gen1+, Gen2+ and Gen3" mean?
Night vision has been around since World War II when the US Army introduced the world's first night vision device, affectionately called the "snooperscope". These early systems used "active infrared" technology that required huge infrared light sources to function. Clumsy as they were, these early monster devices were the beginning of all night vision to come and were referred to as Generation Zero, or Gen0 for short.
It wasn't until the Vietnam war that the first "passive infrared" night vision devices were developed. Though still very large, all these early Gen1 devices needed to function was a cloudless night and a full moon. Today's Gen1+ products, though much smaller, much brighter and much more reliable, are essentially the direct descendants of that 1960's technology.
Gen2+ scopes were developed through the '80s. The image tubes in these units added something new called a micro-channel plate that significantly boosted their sensitivity. In addition to doubling the system light amplification the new Gen2 and Gen2+ scopes had 50% better viewing clarity. When you hear night vision wonks talk about "resolution" this is what they're talking about.Gen3 scopes represent our most current technology. In addition to the micro channel plates found on Gen2 units, Gen3 devices upped the ante once again with the addition of something called a Gallinium Arsenide (GaAs) photo cathode. Use of this exotic element results in the best performance specifications. Put bluntly, they really do turn night into day.
Gen3 night vision equipment also offers the greatest depth of features, including intuitive operating controls, fully automated image tube protection, rapid flash recovery capability and numerous on-screen indicators. As an export controlled product, Gen3 night vision products (and many Gen2+ product) cannot be exported from the United States.
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3 - What performance should I expect from Gen1+, Gen2+ and Gen3?
The two most important specifics for any night vision device are resolution and signal-to-noise ratio. In fact one of the main parameters for determining whether a night vision device can be exported is the multiple of these two specifications, also know as Figure Of Merit.
Resolution
Much like a television or computer screen, the more information that can be packed onto your night vision image tube, the clearer it will be. Measured in line pairs per millimeter (lp/mm), the higher the specified lp/mm the better.
When you compare an average Gen1+ 25 lp/mm image tube to the typical resolution that you'll find on a Gen3 tube - 64 lp/mm - it's pretty obvious that a Gen3 tube is going to be better. No matter how you slice it, 150% better resolution means a better image.
Signal-to-Noise ratio
So is giant resolution all you should be looking for in your image tube? Well, though it's a good start keep in mind that the real function of your night vision system is to perform well under incredibly low light conditions. This is where the signal-to-noise measure becomes important.
It provides a measure of the light signal that reaches your eye divided by the perceived noise that you actually see. For example, "noisy" tubes look like there's a snowstorm going on inside the tube. Even a very bright tube that's full of snow (noise) is going to produce lousy results. A good Gen3 tube will have a signal-to-noise ratio in the high 20s while Gen1+ ratios will languish in the single digits.
Bottomline, the very best image tubes will have very high resolutions (as high as 73 lp/mm) and a high signal-to-noise ratio. While most night vision devices will provide specifications detailing resolution, only the highest quality tubes provide data sheets detailing their signal-to-noise ratios.
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4 - Is night vision legal? Is it safe to use?
Night vision hand scopes, binoculars and goggles are all legal to use. The use of night vision weapons sights may be restricted in some jurisdictions, so it's best to check with your local authorities on this issue.The export of some US-made night vision equipment from the United States requires an export license. For further details, review our FAQ on night vision export considerations.
On the question of safety, the answer is that night vision is absolutely safe to use. Though it makes for a great, low-budget movie effect, you will not go blind if you accidentally point your night vision unit at a bright light.
In real life, all night vision devices are built with automatic brightness control circuitry (ABC) that dims the unit - or shuts it off completely - if you point it at a bright light.
And no, night vision is not radioactive. Nor will looking directly into your scope's infrared light source burn your eyes out. While certain laser-based illuminators would definitely be harmful to look at, the infrared illuminators that are built into most night vision products use low power infrared diodes similar to those that built into most TV remote controls. They're harmless.
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5 - What about the export of night vision? Is that possible?
The answer is sometimes yes, sometimes no... it depends on the product. To determine whether any specific product can be exported please refer to that product's "Export Sales" section to determine its export status.
While our shopping cart system has been designed to prevent the export of prohibited products we always recommend alternates for you to consider. To review, here's a quick review of the export status of the different generations of night vision:
Gen1+ exports
All Gen1+ products can be freely exported.Gen2+ and Gen2+hd exports
Though PVS-7 Gen2+ Goggles cannot be exported the "Export Sales" section of that product's catalog description details a recommended alternate.NVS-14 Gen2+ Mono-Goggles can be exported with an export approval. Please refer to the "Export Sales" section for details on how you can receive that approval with our assistance.
DEP-Photonis SuperGen and XD4 exports
These products can be exported with the appropriate approvals. Please refer to the "Export Sales" section for details on how you can receive those approvals with our assistance.Gen3 exports
Gen3 cannot be exported. Please refer to the "Export Sales" section for our recommended alternates. In all cases our recommended DEP-Photonis alternates will meet or exceed the technical specifications of the Gen3 product that you had been considering.Export Restrictions Warning
Export of US-made night vision equipment is prohibited without a U.S. Department of State Office of Defense Trade Controls export license in accordance with International Traffic in Arms (ITAR), Title 22, Code of Federal Regulations Part 120-130. For more information contact the Office of Defense Trade Control at (202) 663 2700.
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6 - How do I focus my night vision unit?
When you first get your night vision unit, get familiar with the focus adjustment of the front objective lens and the eyepiece ocular(s). On new units they may be stiff, but they will loosen with use.
On most units the lens cap has a tiny hole drilled into it that will permit a minuscule amount of light to enter, permitting you to test it under daytime conditions. Remember though, never remove the lens cap and operate the unit during the daytime.
Focusing a night vision unit is a two-stage operation. First, aim at an object and focus the front objective lens as best you can. Now focus the eyepiece ocular(s). This second stage is important as it sets up the unit to permit your eye to focus on the green, glowing image that your unit's image tube is generating.
Always remember to guide new users through this two-stage focus process. First time night vision users often forget to make the critical eyepiece ocular adjustments.
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7 - Which are best? Scopes, binoculars or goggles?
Scopes are generally your least expensive option because they contain only one night vision tube. No matter which Gen scope you choose - Gen1+, Gen2+ or Gen3 - all will provide you with excellent night vision at a great price.Binoculars, because they contain two image tubes, cost more than a scope. They tend to be easier to use however, especially if you're new to night vision. While pretty well everyone knows how to use binoculars, scopes take a bit of learning to get used to looking with one eye only. Binoculars also deliver true depth perception while scopes do not.
Goggles are usually the most expensive as they are designed to wear on your head, freeing your hands to do other things. In addition to wearing them, many goggle systems are designed to let you remove the optics unit from the headset and use them just like binoculars, often with optional high power lenses.
If goggles appeal to you but the price is too high, consider a Mono-Goggle system. Just like a scope the price goes down because only one night vision tube is required, but in this case you can wear it while walking around.
