Darkness is one of the biggest problems of human existence. In both ancient and modern times, the darkness that comes with night has prevented humans from knowing the dangers of their surroundings. And man has always found ways to dispel the unknown and fear that darkness brings with fire and electric light.
But for the military, the unknown and fear that pervades the darkness can be exploited. Twilight becomes the best camouflage for soldiers and the most effective time to launch an attack. How to use the darkness to achieve military objectives has become a must for strategists.
To keep the darkness on your side, you have to rely on two types of equipment: night vision and thermal imaging.
Today I would like to introduce you to night vision. How does it work?
A night vision device, as the name implies, is an electronic device that enhances vision in low light or dark environments. They are generally divided into active infra-red night vision devices, micro-optical night vision devices and thermal imaging cameras.
They are called "active infra-red" because of the principle of their operation. The infra-red light of a night vision device first emits an infra-red beam to illuminate the target and then converts the infra-red image reflected from the target into a visible image, thus enabling night vision. Impact. But this active infrared night vision, as we all know by its principle, is a bit of a hassle. The infra-red light must be turned on every time to illuminate others. Although the infrared beam emitted is invisible to the naked eye, it can be caught by an enemy in the opposite direction if there is an infrared detection device on the opposite side.
Microlight night vision, in the darkness of nature's night, as we all know, is even darker and there is still a bit of sky and moonlight. It is impossible to see anything in total darkness. These skylights bring some light reflections to the ground environment, but they are too weak to be seen clearly by the naked eye.
The principle of micro-light night vision is to convert this very weak natural light through the night vision device using a photocathode for photoelectric conversion. It hits the night vision device's fluorescent screen at a very high speed. It is an image enhancement technology that enhances the faint light in the environment that is imperceptible to the human eye and converts it into an almost invisible image.
The principle of microscopic night vision is obvious to everyone, it is the amplification of faint light. Many people find a situation in games and films. Even in the pitch black of night, you can see clearly with night vision goggles, but suddenly the enemy turns on the headlights and creates a large light source. This does not make a normal light bigger and makes a blind person wearing night vision goggles bigger. Is this going to happen? It does happen with older or some civilian low-light night vision devices. Sudden exposure to bright light can cause blindness and even burn out night vision goggles.
But today's modern military night vision goggles have added an "anti-glare" design. When exposed to bright light, the night vision goggles adjust an automatic gate valve to turn down the light, creating an anti-disturbance effect. If the light is too bright, it will also force an automatic shut-off to protect the user's eyes and equipment.
Many people must be wondering why night vision devices are basically green. Actually, night vision devices not only have green screens, but also brown and yellow, or blue and grey screens.
The reason why night vision devices display a green screen is because the core component of a night vision device is called an "image intensifier tube", which converts the weak light received into an electron beam, which blasts the phosphor to enhance and amplify the image and produce an afterglow effect. This phosphor is usually made of zinc sulphide, which is not very effective in other afterglow effects, and may also produce trailing shadows and screen flicker.
This zinc sulphide phosphor emits green light. Also, early radars, oscilloscopes, etc. did you notice that they were all green pictures because they all used zinc sulphide phosphors. Therefore, it seems that night vision goggles are usually green. However, not only are night vision goggles green, but they also use white phosphor tubes. A picture produced using a white phosphor tube will show this blue-grey colour. This colour is closer to a black and white image and can rely to some extent on contrast to enhance the ability to identify objects while maintaining the same image sensitivity as green phosphor.
Post time: Apr-13-2023
