The working principle of infrared night vision devices
Simply put, the principle of an active infrared night vision device is to convert the invisible light (low light or infrared light) signal from the target into an electrical signal, then amplify the electrical signal and convert it into a visible light signal to the human eye.
Professional explanation: The principle of an active infrared night vision device is to focus light on an image intensifier through an eyepiece to collect and enhance existing light. Inside the intensifier, a photocathode is "activated" by light and converts photon energy into electrons. These electrons are accelerated through an electrostatic area located inside the intensifier and collide with a phosphorus surface screen (like a green TV screen), forming an image visible to the human eye; After accelerating the electrons, the brightness and image clarity have been enhanced, as shown in the following figure.
Low light night vision devices are instruments that can see objects at night by incrementally processing weak light to make them visible to the naked eye. In order to achieve better results, most low light night vision devices now come with infrared emitters that can assist in lighting when the light is too dim. However, due to its easy detection, commonly referred to as "red exposure" by domestic enthusiasts, it is now mostly used in the civilian market.
Working principle of passive infrared night vision device (thermal imaging)
Principle: Thermal imaging infrared instrument is an instrument that uses the basic principle that all objects above absolute temperature zero (-273 ℃) emit infrared radiation, and uses the difference in infrared radiation between the target and the background to discover and identify targets.
Characteristics: Due to the different infrared radiation intensities of various objects, people, animals, vehicles, airplanes, etc. can be clearly observed, and are not affected by obstacles such as smoke, fog, and trees. It can work both day and night. It is currently the most advanced night vision observation equipment mastered by humans. However, due to its high cost, thermal imaging can currently only be applied in military applications. Although thermal imaging has a wide range of applications, such as electricity, underground pipelines, fire and medical care, disaster relief, industrial testing, etc., it is still difficult to popularize at present.
