How to select the most suitable night vision device?
First night vision device was designed in 1926. That technology was applied to military equipment only. First combat night vision devices were used by German army during the Second World War. Nowadays night vision devices are standard equipment of virtually any army around the world. The development of technology and lower prices caused increase of availability on the civil market. Night vision devices are widely used by the emergency services, security guards as well as amateurs, such as hunters, outdoor games' lovers (e.g. ASG, paintball, survival, etc.) and other users who need equipment specially designed for facilitating observation and moving around in the dark.
How a night vision device works?
A night vision device is an optoelectronic system based on a light converter which amplifies residual light from a few to dozens of times, by generating image visible to the human eye. It's worth remembering that night vision devices, in order to work properly, need a minimal amount of external light, such as moonlight, starlight or residual light from other light sources. Even the very remote ones, or light generated by a IR illuminator mixed with the night vision device (most night vision devices are equipped with build-in short-range IR lamps mated with special illuminators of very high power and wide range as well as light-intensity adjustment and infrared light beam focus adjustment).The residual light falls through the specially adjusted lens designed to focus the dispersed light. The beam of electrons which falls on the photocathode (an optoelectronical system which emits electrons when exposed to the light). The beam of electrons is subsequently amplified many timesand redirected on a phosphor screen (a luminophore) designed to transform the beam of electrons into the beam of photons, and thus generates the visible image in the eyepiece. Phosphorous, covering the luminophore, emits green light due to the fact that the sensitivity of human eye is the highest in that particular band. Human eye recognizes a multitude of hues in the 500-560 nm band which corresponds to the green and blue. This band makes it possible to recognize a lot more details than in the case of other colours.
What to remember when using a night vision device?
Modern night vision devices are durable and can be used for many years. Properly used night vision device can work for as long as few thousand hours before first signs of lamp malfunction. This is completely normal that the lamp's luminophore gradually burns out. After working properly for some time, the device starts to generate gradually darker and darker image.
The proper operationof a night vision device and protecting it from a strong direct light is a paramount issue. Intensive light causes rapid burn-out of the luminophore and, in some cases, even an instant failure. Short-time illumination causes gradual lamp malfunction, image darkening and appearance of dark spots. It is important to remember about few short rules:
- Important information
- always put on the lens cap onto the lens during the day (even when the device is turned off),
- never turn on the device during the day or in well-illuminated places without firstly ensuring that the lens cap is put on,
- avoid exposing the unprotected lens to an intensive artificial light, such as floodlight, torch or open fire,
- it is advisable to follow the safety recommendations above despite the fact that new models of night vision devices are often equipped with an AGC safety mechanism (Automatic Gain Control), which automatically cuts off the power supply after detecting exposure to a very intense light. Following the recommendations guarantees longer device's lifespan and fewer failures.
It is completely normal to see dark spots in the night vision image. This is a result of the lamp's imperfection and is noticeable even in case of the new devices. Spots don't affect neither the image quality nor the functionality of the device.
What is the range of a night vision device?
The range of a night vision device depends on many factors. The amount of residual light and type of landform are of the most importance. A night vision device behaves differently during a bright moon night than during a cloudy night. A snowy clearing provides far better visibility than a thick forest covered by a layer of decayed leaves, which absorb great amounts of light. In case of total darkness the range depends completely on the artificial IR illumination source. Most night vision devices are equipped with a built-in short-range illuminator providing good visibility in a 20-30 m range. Moreover, the night vision device can be also assisted by an external long-range illuminator. It can be a torch emitting near infrared light and equipped with a power adjustment and a light beam focus. Depending on a variety of conditions, it can illuminate the terrain in a 100-400 m range.
It is also important to differentiate between detection range (a distance small enough to detect an object) and recognition range (a distance small enough to distinguish the details and differentiate between a man and a tree trunk). However, both ranges strongly depend on the size of the object. It is certainly easier to spot a roe deer than a fox. The model of lens and its magnification are also important parameters. Night vision devices with a lens magnification from 1x to 8x are widely available on the market. The stronger the magnification the greater the range of a device. Generally, it can be estimated that I/I+ generation devices make it possible to detect a man from 30 to 150 m whereas II/II+ generation devices offer three times greater range (from 150 to 600 m).
- The range depends on the magnification
- 1×: up to 80-100m,
- 3×: up to 150-200m,
- 5×: up to 300-350m,
- 8×: up to 600m.
What are the generations of night vision devices?
Depending on the quality of an image amplifier and applied technologies, night vision devices can be separated into classes called generations. This is a very rough division but it makes it possible to unambiguously assign a device to a particular image quality.
Generation I – the most popular and the cheapest class of night vision devices provides relatively bright and clear image, without adding too much to production costs. Image amplifiers in this class of devices offer about 1000-5000 times light amplification. Nowadays, I+ devices are the most common class due to their higher image resolution, higher sensitivity and smaller image distortion. This type of night vision devices is sufficient for most of the less-demanding tasks, such as sailing, wildlife watching, outdoor games or surveillance of a protected area of lesser importance. The low cost is the biggest advantage here.
Generation II – is a great leap forward when it comes to quality due to insertion of an additional microchannel plate (MCP) between the photocathode and the intensifier tube. Physical phenomena occurring in the MCP cause electron multiplication in the electric field. It is made of glass covered with holes of very small diameter which are positioned at a specially adjusted angle. Due to metallization of external surfaces polarized with a voltage of 100-200V and unparalleled channel positioning each electron collides with the walls (from 3 to 8 times when passing through the plate) and causes subsequent emission of 2-4 secondary electrons. This solution makes the image intensifier a way better than the I generation (up to 50000 times better intensification) and contributes to the image brightness and detail. Its main disadvantage is a considerably higher production cost resulting from the necessity to install additional converter, which rotates the image by 180°. There is also a II+ class characterized by better image parameters (reduced distortion) and lower power consumption. Due to considerably higher price this type of night vision devices is used mainly by professionals (army, police, border guard or forest guards) for surveillance of important buildings or by hunters for detecting the wildlife.
Generation III and IV – the most modern night vision device generations which are freely available on the European civil market. Generation III are virtually II/II+ devices with improved resolution and lifespan. The difference between class III and II is considerably smaller than that between the II and the I generation. Generation IV is used rarely due to its very short lifespan (it is in a prototype phase). The simplest model can be purchased for less than 20
CORE™ (Ceramic Optical Ruggedized Engine) – is an original technology designed by Armasight. The image intensifier is made from ceramic mixed with metal alloys, like in case of II / II+ generation, but without MCP. This solution combines the main advantage of I generation (i.e. affordable price) with the image quality of higher models. Its main features include: improved light intensification coefficient, high sensitivity and very high image resolution, which is even higher than in case of II / II+ devices. Blur and other image distortion plaguing cheaper models were also eliminated. Due to their ceramic core CORE™ night vision devices are more resistant to mechanical damage than devices based on glass components.
Digital night vision devices – works on a completely different principle than the models mentioned earlier. They have no photocathode, intensifier tube or phosphorous lamp. These components were replaced by a digital light-sensitive CCD matrix (similar to matrices used in digital cameras or video cameras). The image from the matrix is digitally processed and displayed on a LCD placed in the device's eyepiece. When it comes to quality and sensitivity, good digital night vision devices can be placed between I and II generation. Additionally, they offer a variety of unique functions, such as colour palette adjustment, brightness and contrast adjustment or displaying additional information on the LCD screen (e.g. reticle). Their main advantage is a virtually unlimited converter's lifespan and insensitivity to bright light.
Which kind of night vision device is right for you?
Generation I and II night vision devices can have different designs depending on the application. There are monoculars (lunettes), binoculars - binoculars, glasses for attachment to the head or helmet, sights and night vision attachments for weapon-mounted lunettes. When choosing, it is necessary to think about what kind of equipment we need and what features are crucial for us.
- For tactical, as well as professional use in the military or amateur paintball game, a lightweight night vision goggle or night monocular with a head mount that does not take up the user's hands is best suited. To make movement in the field intuitive, it is best to use a model with single magnification and a wide angle of view. These models are, for example, the AGM Global Vision PVS-14 Omega Generation 2+ tactical night vision or the AGM Global Vision Wolf-7 Generation II night vision with head mount kit or the AGM Global Vision Wolf-14. A great solution is the GSCI PVS-7 goggles.
- When hunting, monoculars and night vision scopes with 3x-5x optical zoom are very good for field observation. This will guarantee a higher range of recognition while maintaining a relatively wide field of view. In this case, second generation devices are recommended. A very good one is the Bestguarder NV-900 (with fixed optics with 4.5x magnification) or the AGM Global Vision Foxbat-5 binoculars.
- For security personnel guarding a closed area, digital night vision is certainly useful. Because it is light resistant, it performs well where strong lighting is installed that can change dynamically. An example of such night vision is the Armasight NV400-B. For the case of surveillance of more important objects, it works - similarly to second-generation telescopes and binoculars for hunting.
- Very often night vision is also used for night shooting. Gun-mounted night vision devices are used in the military, police and other law enforcement agencies, also for hunting and sport shooting. There are several options when it comes to choosing the right device. The most recommended is the use of a night vision attachment on an optical sight used for shooting in daytime conditions, for example, the AGM Global Vision Comanche 22. Such night vision is installed very easily and quickly in front of the scope lens via a suitable adapter, there is no need to re-adjust the sighting system, and the distance of the scope from the eye does not change, which makes targeting more difficult. The Armasight range includes attachment models to suit different rifle scopes and shooting at different distances:
- CO-mini: 80-120m, recommended scope zoom up to 4x
- CO-MR, CO-X: 120-170m, lunettes up to 8× zoom
- CO-LR: 600-900m - 12× magnification (16-18× magnification is also possible)
- A very important parameter is the resistance of the night vision to recoil caused by gunshot. Below is an indication of the calibre that can be used with the various models that can be mounted on the gun:
- 1st gen.+ (WWZ, Orion) - .223 Remington cartridge, about 1800J
- CORE (Vampire, Spark) - .308 Winchester cartridge, about 3600J
- + (Nemesis, Spear, Sirius) - .308 Winchester cartridge, about 3600J
- 2nd gen + military models ( Vulcan, CO-mini, CO-MR, N-14, Nyx-14) - .30-06 Springfield cartridge, about 3800J
- Apollo thermal imaging attachment - .308 Winchester cartridge, about 3600J
- CO-LR - .50 BMG cartridge, about 18000J
- For amateur use, hiking, camping or nighttime wildlife viewing, a simple low-cost solution will suffice. An example of such night vision is the PARD NV019 V2 model, which is characterized by very careful design, good parameters. The main features of this model are 8x digital zoom, HD video recording and Wi-Fi module.
Nowadays, everyone can buy night vision, devices are becoming more and more affordable and the market offers a large selection of devices tailored to specific customer requirements. Armasight and AGM is a young company originally from the USA, founded by enthusiasts and experts with vast experience. The brand's products are characterized by a very good quality of workmanship and excellent technical parameters. Thanks to the practical knowledge of the designers, a variety of models are offered and in the wide range of products every user will find the solution best suited to his needs. The distributor of Armasight is Spy Shop.