Infrared Night Vision Instrument Infrared Night Vision Imaging Technology
The visible light at night is very weak, but the infrared rays that cannot be seen by the human eye are abundant. Infrared cameras use photoelectric conversion technology to help people observe, search, aim, and drive vehicles at night. Although infrared was discovered early on, the development of infrared remote sensing technology has been slow due to the limitations of infrared components. It was not until 1940 when Germany developed lead sulfide and several infrared transmission materials that the birth of infrared remote sensing instruments became possible. Afterwards, Germany was the first to develop several infrared detection instruments such as active infrared night vision devices, but none of them were actually used in World War II. There are two types of infrared cameras: active and passive: the former uses an infrared searchlight to illuminate the target and receive 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".
Infrared night vision imaging technology
Infrared night vision technology has gone through early active infrared night vision imaging technology and now passive infrared (thermal imaging) technology. Infrared detectors were first developed using unit detectors, but later developed into multi element linear array detectors to improve sensitivity and resolution. They have now evolved into multi element array infrared detectors. The corresponding system has achieved a leap from point detection to target thermal imaging.
(1) Active infrared image conversion technology (near infrared region).
This technology utilizes the principle of photoelectric image conversion to achieve nighttime observation. This type of instrument includes two major parts: an infrared light source and a night vision mirror containing an image converter. The infrared light source illuminates the target, and the night vision mirror converts the invisible infrared image into a visible image. This type of technology began research in the late thirties and was developed and applied during World War II. Rifle sights equipped with active infrared night vision devices are widely used on Pacific battlefields. Around the 1960s, this technology became mature, with observation distances of up to 3000 meters. Later, it was widely equipped in the military, but due to its low sensitivity, high thermal emission, high power consumption, large size, limited observation distance, and easily exposed fatal weaknesses, it was gradually replaced by later developed night vision technology. Currently, only a few countries have a small number of equipment.
(2) Passive infrared night vision technology (in the middle and far infrared regions)
Infrared thermal imager is one of the most promising infrared detectors, representing the development direction of night vision equipment. It uses an internal photoelectric semiconductor device as a detector to convert the radiation image of the scene into a charge image. After information processing, the display device converts it into a visible image.
