| Night vision devices have recently become affordable | | | | before it hits the image intensifier and can amplify |
| enough for the general public, who has found | | | | available light approximately by 20,00-75,000 times. |
| numerous applications, some very different from the | | | | These are by far our most highly recommended grade |
| originally intended uses. They of course have several | | | | if you can afford them - much harder to 'outgrow' than |
| commercial and professional applications as well. | | | | Gen-1. |
| Night vision devices are frequently used for: | | | | Generation 3 |
| * spelunking | | | | These are very costly devices, and are naturally suited |
| * scouting games | | | | for those people whose lives (or livelihoods) depend on |
| * camping and exploration | | | | night vision, e.g. law enforcement, military, security |
| * observing wildlife | | | | personnel and even researchers. Of course, hobbyists |
| * hunting | | | | find a use for them too. |
| * surveillance | | | | Generation 4 |
| * nighttime security | | | | As with anything, there are always enthusiasts that |
| How they work | | | | want to buy the 'best', and spend a lot of cash on |
| The 'trick' with night vision devices is that they collect | | | | Generation-4, which are full military-specification. It |
| infrared and visible light (natural or artificial) with an | | | | should just be noted that to export these devices out |
| objective lens and focus it on a battery powered | | | | of the USA is extremely difficult, requiring special |
| image booster, which amplifies the signal as follows: | | | | permits. I don't recommend them anyway, as they are |
| * a photo-cathode inside the tube absorbs the light | | | | overkill for most applications. |
| energy and converts it into electrons | | | | Selection criteria 2: Intended use |
| * the electrons hits a phosphor screen, which glows to | | | | To choose a type of night vision device and its grade, |
| form a bright enough image for the user to see | | | | it is important to figure out what your the worst |
| through eyepiece(s) | | | | operational conditions will be. Another thing to consider |
| Note: the phosphor screen is intentionally made green | | | | is whether you will be able to use an infrared illuminator |
| because the human eye can see more shades of | | | | (built-in or accessory), since they drastically improve |
| green than any other color. This gives a very a realistic | | | | range and image quality. As an example, infrared |
| 'gray scale'-like image, much like when you make a | | | | illuminators are probably well suited for cave |
| color photo 'black and white' with your computer. | | | | exploration, while they may not be for law |
| As can be expected, the major difference between | | | | enforcement tactical operations. |
| various 'grades' (and prices) of night vision devices is | | | | Here's a hypothetical example of one would choose |
| the quality and sophistication of the intensifier tube, | | | | an instrument for the law enforcement tactical |
| which brings us to the primary selection criterion: | | | | operations, based on specific needs. |
| Selection criteria 1: Light Amplification | | | | Requirement: |
| Generation 1 | | | | * low light |
| These instruments have medium gain values giving | | | | * no infrared illuminators |
| good images, and their intensifiers are made up of | | | | * 'hands-free' |
| simple electrostatic tubes, which are able to amplify | | | | * only ±75m range needed |
| available light by 500-20,000 times. They work more or | | | | * very good clarity |
| less as I described above. | | | | * wide angle view |
| While Gen-1 night vision devices cost less and are | | | | Solution: |
| almost always larger and heavier than instruments | | | | * Generation 2 or better |
| from the other categories, don't turn your nose up at | | | | * goggles |
| them. If you don't have a big budget, and do not need | | | | * Gen-3 is probably best |
| to use your night vision device in very dark | | | | * Gen-4 would be an expensive overkill! |
| environments, then they make good financial sense. | | | | In conclusion, to choose a night vision device, one |
| Also, just using an infrared illuminator greatly expands | | | | needs to learn the limitations of the different grades, |
| the usability of these devices - even when there is | | | | know the applications of the different types (binoculars, |
| ZERO ambient light present. | | | | goggles, etc.) and very importantly determine the |
| Generation 2 | | | | 'worst-case scenario' that the device would be used |
| These are smaller, lighter and more energy efficient. | | | | under. |
| They are able to pre-amplify the available light signal | | | | |