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Night vision

Unlike certain animals with night vision such as the owl and cat, which can see perfectly in the darkness, humans need light to identify what's around them. Although changes in the pupil allow vision to be adapted to the ambient light, the human eye has no night vision capability and therefore can hardly see anything in the dark or at night.
Fortunately, to make up for this handicap there are devices - optical instruments and image capture accessories - that allow us to see in the dark. Very useful outside at night in particular, these devices are described as having scotopic vision, or night vision. They sometimes also have other features such as zoom and recording.

What are night vision devices for?

Night vision devices allow us to see at night or if there's insufficient light. This means they're widely used by professionals who work at night: security personnel, wardens, border guards, marine navigation personnel, etc. These devices are also very useful in the military, which is where the first night vision products emerged and the most sophisticated devices are found.
However, professionals aren't the only ones to use night vision instruments in the absence of daylight. Anyone who performs an activity, practice or leisure pursuit outdoors, at night or in the darkness, is liable to use a night vision device. This is notably the case with campers, hikers and naturalists, as well as fishermen, hunters, etc. Cavers and people who need to navigate may also require night-vision binoculars.
Devices that have night-vision image capture features are also very useful, whether for observing nature or animals when it's dark or capturing footage using an infrared camera as part of a security video surveillance system.

How do night vision devices work?

Most night vision devices are in fact light amplifiers. They need at least some light, whether from the moon or the stars, to provide a decent image. These are known as residual light amplifiers. Their photosensitive optical sensors accentuate the reflection of light to provide vision that's as similar as possible to vision during the daytime. Meanwhile, other devices use an infrared beam that acts as a backup light when the light level is too low. The former is known as passive technology, while the latter is called active technology. Some products combine both technologies for improved performances.
It's nevertheless important to note that the term infrared can cause confusion: when we talk about night vision, as is the case here, we mean backup infrared lighting rather than an infrared camera, which captures thermal radiation, and therefore heat, from bodies in the absence of light. These devices are very specific and are used by the army or to locate victims during natural disasters for example.
Some products use digital night vision technology. This means that instead of using a light amplifying tube, they have a CCD or CMOS sensor that's sensitive to infrared. The image is then digitally processed and can be saved. This is the technology that's used in surveillance cameras. Discover all our products

The various night vision devices

Many different night vision products are available today: binoculars, goggles and surveillance devices, from many different manufacturers and at all kinds of prices. Choose the product that's best for you based on your needs, how frequently you'll use it and the performances you require.
  • Monocular or binocular device?
    The range of existing models includes monocular devices (also called telescopes) and binocular devices. Binoculars are more comfortable to use and fatigue the eyes less. Nevertheless, they're fairly expensive and re-adapting to the ambient darkness after using them causes momentary blindness. A monocular device like a telescope doesn't have this drawback: because you're only using one eye it's easier to regain your normal vision after using it, which is less of a handicap. The cost of monocular devices is another argument in their favour, as they're more affordable compared with binoculars. A telescope is also smaller, easier to handle and lighter, which makes it easier to transport and use for observation.
  • Which generation of device?
    Night vision instruments are usually categorised according to their generation. This includes the following:
    -First generation telescopes and goggles: these detect and amplify residual light using amplifying tubes (passive technology). They're affordable and perform well enough for use by amateurs who don't need a long range.
    -Second generation products: improved by the inclusion of a photocathode and glass micro-tubes that amplify the light exponentially, their range is greater and they perform better even with very low initial light. These second-generation binoculars are nevertheless more expensive than the first-generation version.
    -Third and fourth-generation instruments: these binoculars provide even more advanced performances thanks to a chemical filter that lights up the darkness and amplifying tubes that are even more sensitive to infrared. Using these devices, light amplification can reach x50,000. These telescopes and binoculars are nevertheless very specific, very expensive and are designed for professional or military use.

Night vision surveillance devices

In addition to binoculars and telescopes, there are also night vision products dedicated to security and surveillance. This is the case with top-of-the-range indoor and outdoor video surveillance cameras: to secure the premises they're installed in, they need to provide and/or record clear and high-quality footage even in low light conditions. A good video surveillance system therefore needs to be equipped with an infrared night vision device to allow discrete observation and take footage regardless of the time or the weather conditions. Good-quality products also usually have a projector to properly light up the area if necessary.
You need to consider various factors when choosing a night surveillance device: whether or not it has a zoom feature, the range that the camera needs in order to provide a clear image and therefore the quality of the infrared lighting. Lastly, choose a product that's the right price for the intended use (the level of security concerns, the value of the items being protected, etc.).
Lastly, other accessories may require night-time performances, such as a street intercom, to identify visitors when the light is poor or when it's dark.

Night vision and legislation

Are you about to buy a night vision device and are wondering about the legalities surrounding these types of products? Rest assured, these accessories (telescopes and binoculars) are freely available with no age or usage limitations. The only restriction concerns the use of a hands-free instrument: in this case the device is equivalent to a category 2 weapon, which makes it similar to a firearm. To comply with the law, notably the order of 11 September 1995, do not attach your telescope or binoculars to a helmet or a hands-free accessory.
As far as surveillance cameras are concerned, their performances in the dark have no effect on the legal provisions concerning the use of video surveillance. Rules issued by the French national commission for data protection and liberties (CNIL) apply equally at day and at night.

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