Military forces, including infantry soldiers, vehicle crews and special forces operators, often require devices that will allow them to see at night or under poorly lit conditions. These devices will aid in the successful execution of missions such as surveillance, target acquisition, patrolling, navigating, and search and rescue.
Night vision systems are based around two different technologies:
Image intensification, which is the most common technology in devices referred to as “night vision”, captures ambient levels of light from sources such as stars or the moon. The photons from this light strike a plate inside the image intensifier known as a photocathode. The photocathode releases electrons in response to this, and these electrons are multiplied and used to create an image with the same pattern as the original photons that is visible to the human eye.
Image intensifier-based night vision devices can be categorized into a number of generations, from 0 to 4, based on the technology used. Most devices currently in use for military applications are either Generation 3 or Generation 4.
Thermal imaging-based night vision devices pick up thermal-infrared radiation, which is related to temperature, emitted by objects. The temperature information received by the detector is translated into electrical signals, which are then used to create a color-coded output image that varies according to the intensity of the infrared radiation. Thermal imaging is particularly useful for locating humans as well as equipment that has been recently used such as vehicles and weapons systems. It can also see through smoke and haze, unlike image intensification devices.
Fusion Night Vision Systems
Some fusion night vision systems utilize both image intensification and thermal imaging to harness the advantages of both. These systems tend to be heavier and draw more power than devices that use only one technology.
Night vision capabilities may be found in a variety of devices, including night vision goggles, binoculars, monoculars, cameras and weapon sights.