Night vision devices are devices that are specially designed to provide a vision for an object in places with low-light conditions such as in a place filled with smoke, dust, or fog or at night. Night vision is used to observe or study objects or animals in the dark, to monitor people’s movement in the dark, to carry out a rescue search amongst others.
Night vision devices generally work in two ways; either by thermal imaging or by image enhancement. In the image enhancement technique, the camera lens captures a very small amount of light (light from the moon or the stars reflected by the image), which is then transferred to the image-intensifier tube where the electron-optical converter (EOC) converts the picked weak-reflected light into electrons changing the image into black and white. As the electrons travel through the tube, the tube increases the few electrons to many thousands by releasing more electrons. These thousands of electrons are then transferred to a phosphate-coated screen which gives the resulting image a green coloration. In the thermal imaging technique, the lenses capture high-frequency infrared lights emitted by an object, an array of Infrared ray detector elements then interpret the received infrared rays as a heat map which is then converted to electrical impulses. The processing unit of the device then converts the impulses into an image, which is then sent to the display.
Image-enhancement night vision devices use reflected energy which means that they need a little amount of light, whereas thermal imaging night vision devices on the other hand can work in the complete absence of light since they use emitted energy.
Types of night vision devices
- Night Vision monoculars
- Night Vision binoculars
- Night Vision goggles
- Night Vision scopes
- Night Vision cameras
- Night Vision glasses
Night Vision Monoculars
Monoculars are single eye unit optic devices. Their lightness in weight and compact size makes them ideal for head mounting. They are so portable that they can easily fit into the pocket. During usage. They can be held with one hand, attached to a helmet, attached to a riflescope, or mounted directly on a weapon.
However, this device has its pros and cons. Their cons include: they are not good for long term usage as they can lead to eye fatigue, they do not cover a wide angle of viewing and they are not the best for tracking objects that are changing positions.
Night Vision Binoculars
Binoculars are double eye unit optic devices that come with built-in magnification. They give a wider range of view when compared to monoculars and they can be used for the long-term without having to worry about the eye-getting strained. However, they are heavier and less portable, which makes them less preferred for head mounting. Binoculars are also more expensive than monoculars of the same specification.
Night Vision Goggles
Night Vision goggles is a night vision device that can be head-mounted, allows viewing using both eyes but has no magnification.
There are two types of night vision goggles:
- Two-piece night vision goggle that views through a single image tube. In this type, both eyes share a single image
- Two-piece night vision goggles that view through dual image tubes (also known as stereovision goggles). In this type, the eyes see slightly different images.
The advantage of a stereovision goggle over the single tube goggle is that stereovision goggles provide a better depth of perception.
The advantage of the night vision goggles overnight vision monoculars is that they allow the user a better perception of the view and they also have a better navigation ability. The con is that they are less versatile than a quality monocular and they cannot be mounted on riffles or adapted to riflescopes. Another disadvantage of night vision goggles overnight vision monoculars is the weight.
Night Vision Glasses
Night Vision glasses are like yellow-tinted sunglasses. They are usually in yellow because the yellow color is more effective in low-light conditions than other colors.
Night Vision camera
Night Vision cameras are mainly used for security and surveillance. They are used for capturing or recording images
Night vision cameras are divided into two classes based on their use
- Indoor night vision camera
- Outdoor night vision camera
Night Vision Scopes
Night Vision scope is a telescopic-sight one-eyepiece optic device that either can be handheld or mounted on a riffle. They are used by snipers and hunters
There are two types of night vision scopes:
- The larger and heavier scopes known as weapon sights
- The one that can be attached to riffles known as the day/night system
Features to look for in a night vision scope
- Battery power
- Magnification power
- Day/night node
- Eye relief
- Waterproof ability
- Types of crosshair/reticles
Night Vision Applications
The military is very famous for night vision devices. In fact, night vision was originally developed for warfare. Night vision devices are used by the military to carry out military operations including finding enemies at night or in dark apartments, surveying an area at night, and identifying potential enemies in the dark.
Hunting in the dark is the hobby of many, however, the naked human eye cannot see in the dark. This is why night/early mourning hunters use night vision to study their target.
Wildlife researchers and nature watchers use night vision devices as their night vision eyes.
Security and Home defense
In dark areas, night vision cameras are usually used for CCTV cameras. This helps law enforcement and security bodies to properly monitors dark areas.
Safety measures for Night vision devices
- Avoid exposure to bright lights or buy night vision devices that come with an auto cut-off feature. This will make them automatically shut down when exposed to a level of light that is not healthy for the device.
- Clean them only with recommended materials or get specially designed kits for cleaning night vision devices.
- Use the right battery type and power. Also, there are battery bags that are specially designed to keep your batteries dry
- Keep them away from wet environments or get waterproof night vision devices.
- For repair, the device should only be taken apart by professionals
- Do not touch or clean the objective lens with bare hands
- The device should be stored in a dry and safe environment.