One summer evening, I received a task: together with several technical backbones, we checked the performance of two repaired infrared thermal imaging cameras. Although I have learned about night vision devices, I have never tried to use the equipment. Thinking about the amazing night vision technology in the movie, I can't help but look forward to the coming of night.
After dinner, the sky gradually darkened. We set up the night vision device in the observation room on the top floor, connected the power supply, and everything was normal. I couldn't wait to seize the observation position and put my head over. The originally dark world outside appeared so vividly before my eyes, with houses, trees, vehicles, and pedestrians. I could even distinguish the outlines of leaves. All the scenery was covered with a faint red light, and I seemed to be in another space. What I saw was obviously the familiar world around me, but it didn't seem to be the same. Everything in front of me was both illusory and real. The hour-long inspection work passed in the blink of an eye. After removing the equipment and returning to the dormitory, the world shrouded in a faint red light reappeared in my mind for a long time.
Night vision systems are mainly divided into three categories based on different working principles: low-light night vision systems, active infrared night vision systems and passive infrared night vision systems.
During the day, we can see things in nature with our naked eyes because our eyes receive direct or scattered light from the sun reflected on their surfaces. At night, there is still moonlight, starlight, and atmospheric glow. The surfaces of scenery in nature still reflect these lights, but the light intensity is insufficient, so we can only vaguely see the outlines of nearby scenery and large scenery. The low-light night vision system is a night vision system that converts weak natural light images into electronic images that are enhanced hundreds or even tens of thousands of times through an image intensifier, and then converts the enhanced electronic images into visible optical images.
The active infrared night vision system consists of an infrared searchlight and an infrared observation mirror. An infrared searchlight is like a flashlight. It is used to emit near-infrared light with a wavelength range of 0.9~1.2 microns that is invisible to the human eye to illuminate the scene being observed. Infrared observation glasses convert the infrared image formed by the reflected light of the illuminated scene into an image visible to the human eye. Since the infrared light source and its power supply device are relatively bulky and consume a lot of power, the observation range and visual distance are also limited by the power and size of the searchlight, and they have poor concealment and are easily exposed. For example, in the 1973 Middle East War, tanks on both sides of Egypt and Israel were equipped with active infrared night vision devices. Many tanks were discovered and destroyed by the other side because of the use of infrared searchlights.
The infrared thermal imaging camera is a passive infrared night vision system. It uses the temperature difference between various parts of the scene itself and the temperature difference between the scene and the background to image. Since there are temperature differences between different parts of an object, between objects, and between objects and the environment, any object with a temperature above absolute zero will emit infrared rays. At different temperatures, the wavelength and intensity of the emitted infrared rays are also different. Infrared The thermal imaging camera directly receives the infrared light emitted by the target object itself and performs photoelectric and electro-optical conversion to convert the infrared image of the scene into an image visible to the human eye. Compared with other night vision systems, infrared thermal imaging has outstanding advantages.
Night vision equipment truly enables troops to break through the barriers of night and gain the freedom to fight at night. With the continuous advancement of night vision technology, especially the rapid development of night vision technology from direct vision night vision equipment to TV night vision equipment, night vision technology has also penetrated into public security, fire protection, science, transportation, industry and other departments and fields. It has attracted more and more people's attention.
(Source: PLA Daily, Page 12)
Editor: Cao Jin
