More than 50 years ago, only nocturnal animals could see in pitch blackness. However, technical breakthroughs have given humanity the exceptional opportunity to catch sight of objects without extra light. Developers from Germany performed dozens of experiments, leading to the contrivance of night vision goggles (NVRs), which are now regularly applied in miscellaneous aspects of life.
Night vision devices, which enable customers to recognize objects in the dark, were originally forged for military purposes. Nowadays, these gadgets are also going viral in civilian life. Despite their ubiquitous availability, NVRs aren’t simply those devices that can be turned on and off– they require core competency to operate appropriately.
In this article, we will reveal the rudimentary principles of night vision devices and provide answers to questions that are frequently interrogated by new users.
- What does an NVR “see”?
The essence of night vision devices is to obtain a contrasting and lucid image, even in lightlessness. The vast majority of crowd-pleasing models operate via an Electronic Optical Processor (EOP), which converts photons into electrons, accelerating and increasing their flow. This so-called “passive mode of operation” allows you to detect solely the light reflected from objects.
In murky surroundings, infrared illumination is used, which allows you to visualize the invisible IR range with a radiation length of up to 1400 nm. It is interesting to know that cutting-edge technology operates similarly to a video camera: a light-sensitive matrix converts light rays into a digital signal.
- Where are night vision devices used?
Ultimately, NVRs are used in combat conditions for reconnaissance and tracking the enemy. As well, night optics provide additional perks for law enforcement agencies, hunters, wildlife observers, security and search and rescue services, and even for extreme tourists. A separate category of NVRs is night sights used during hunting for aimed shooting in low-light conditions.
- How far can NVRs “see”?
The detection range means the maximum distance at which the device can detect a person 1.7 m tall under conditions of illumination of 0.05 lux (1/4 moon). In general, this parameter directly depends on the illumination and the contrast between the object and its background.
The maximum viewing range for each specific device depends on the generation of the Image Intensifier Tube (IIT):
- GEN I: 100–200 meters;
- GEN II: 400–600 meters;
- GEN III and III+ (for example, B/W ALPHA PHOTONICS or Elbit XLS PVS-14 Gen3+): 800–1300 m.
- Why is the image from night vision devices green?
The fluorescent screens of these devices typically have a green coating, since the human eye perceives the waves of the corresponding spectrum at its utmost. Furthermore, the color does not overwhelm vision in the dark, and the green glow requires less energy compared to white lighting. An alternative option is a white phosphor, added in some models, which sets up a contrasting black-and-white image and works well in closed spaces and densely built-up urban areas.
- What is the “signal-to-noise ratio” in night vision devices?
The parameter, denoted by the abbreviation SNR (Signal-to-Noise Ratio), indicates the ratio of signal power to a similar average noise figure. The resulting figure directly affects image quality. The higher it is, the better the image clarity. For high-profile night vision gadgets, the SNR should be no less than 20.
- What is the discrepancy between a thermal imager and a night vision device?
The core difference lies in the principle of operation of both devices. Portable Night Vision Devices (PNBs) react to light emitted by objects, while thermal imagers respond to heat and infrared waves. The first type of device is designed to recognize objects in the dark, while the second is primarily designed for observation at long distances, particularly during precipitation, dense vegetation, dust, and fog.
- Which type of devices can night vision devices be mounted on?
Portable devices, including night vision goggles, binoculars, and monoculars, are designed for handheld use, helmet mounting, and in some cases, attachment to weapons.
- Can the same PNB be attached to both a car and a helmet?
In vehicles that function without headlights, specified systems are commonly utilized. They consist of cameras with Infrared illumination and a monitor. Thus, portable PNBs and devices designed for cars have fundamentally different designs.
- Does PNB emit any light?
Without IR illumination, the PNB is invisible, even to specialized optics. However, If artificial lighting is turned on, it allows for visibility in complete darkness. In this case, the device can be seen through another PNB or a thermal imager.
- Is it possible to hide from a thermal imager, and how can it be done?
To evade detection by thermal imaging devices, it is worth creating an obstacle to thermal radiation. A wall, stone, thick tree trunk, glass, or foil can serve as effective protection. Special anti-thermal imaging cloaks and awnings are also available on the market.
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