Introduction to the working principle of infrared night vision equipment
Infrared night vision instrument is a military night vision instrument that utilizes photoelectric conversion technology. It can be divided into active type and passive type: the former irradiates the target with an infrared Searchlight and receives the reflected infrared radiation to form an image; The latter does not emit infrared radiation and relies on the target's own infrared radiation to form a "thermal image", hence it is also known as a "thermal imager". The infrared night vision devices currently sold on the market are all active. Passive infrared night vision devices are generally not called night vision devices, but Thermographic camera.
1. Imaging principle of active infrared night vision instrument
Simply put, the principle of an active infrared night vision instrument 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.
Professionally speaking: the principle of active infrared night vision device is to focus the light on the image intensifier through the eyepiece to collect and enhance the existing light. In the intensifier, a photocathode will be "activated" by light, and the photon energy will be converted into electrons. These electrons will hit the phosphorus surface screen (just like a green TV screen) after being accelerated by an electrostatic area located inside the intensifier, Forming visible images to the human eye; Through the acceleration of electrons, the brightness and image clarity have been enhanced, as shown in the following figure.
Low light night vision devices are instruments that increase the amount of light visible to the naked eye in order to see objects at night. In order to achieve better results, current low light night vision devices are basically equipped with infrared emitters, which can assist in lighting when the light is too dim. But because it is easy to detect, which is commonly referred to as "red exposure" by domestic enthusiasts, it is now mostly used in the civilian market.
2. Working principle of passive infrared night vision system (thermal imaging)
Principle: The thermal imaging infrared instrument is an instrument that discovers and identifies targets based on the basic principle that objects with an absolute temperature above zero degrees Celsius (-273 ℃) emit infrared radiation, utilizing the difference in infrared radiation between the target and the background.
Features: Due to the different infrared Radiant intensity intensity of various objects, people, animals, vehicles, aircraft, etc. can be clearly observed, and they are not affected by smoke, fog, trees and other obstacles. They 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, it can only be applied in military applications. Although thermal imaging has a wide range of applications, such as electricity, underground pipelines, firefighting and medical treatment, disaster relief, and industrial testing, it is still difficult to popularize.
