Night vision goggles are a tool invented by people to see things clearly in the dark. However, unlike lighting tools such as candles and electric lights, night vision goggles have extremely strong concealment, giving users vision that penetrates the night, but the person being spied on is unaware.
There are three types of night vision goggles: active infrared night vision goggles, low-light night vision goggles, and thermal imaging night vision goggles. The first and third types of night vision goggles mainly use the infrared principle, while the second type mainly uses the low-light principle. Among them, active infrared night vision goggles were produced the earliest, and they were invented by the Germans during World War II.
In 1940, Germany had already developed several infrared transmission materials. At that time, during World War II, the German army hoped to operate at night to avoid the eyes and ears of the enemy. Although night operations can improve concealment, they are limited because the light is too dark. Real problems have given rise to new scientific and technological products. For combat needs, the Germans quickly thought of applying existing achievements such as infrared projection materials to night operations. They were the first to invent active infrared night vision goggles.
However, it was the U.S. Army that first applied night vision goggles to actual combat. In 1945, the U.S. military landed on Okinawa Island and gained night combat advantages with night vision goggles, successfully killing a large number of Japanese troops. Since then, night vision goggles have appeared in battles many times and have made great contributions to the victory of the World Anti-Fascist War.
How do night vision goggles allow people to discover enemies hidden in the dark? Active infrared night vision goggles adopt an active attack strategy. It uses an infrared searchlight to emit infrared rays, which will be reflected back immediately when they touch targets at a long distance. The reflected infrared rays are received and focused by the objective lens and projected onto the infrared image converter. The infrared image converter converts the invisible infrared image into an electronic image visible to the naked eye through electrical energy processing, so that people can observe the target situation a hundred meters away through the screen.
Depending on the power of the infrared searchlight, the range of its observation is also different. This type of night vision goggles is low-cost and mature in technology, so it was more popular in the early days. But it has a fatal weakness. It has to actively emit infrared rays, so it is easy to be discovered by the enemy's infrared detector, and then expose itself. With the development of human night vision technology, this night vision device has gradually been replaced.
In order to get rid of the defect of active infrared night vision devices that are easy to expose, people are more actively studying new night vision devices. Low-light night vision devices came into being. In 1962, the United States first developed the first generation of low-light night vision devices and applied them to the Vietnam War.
The core technology of low-light night vision devices is low-light enhancement technology, and the core component is the image intensifier. At night, especially in the wild without lights, although we can't see things clearly, we can still see the general outline of things. This is due to the existence of natural light, such as moonlight, starlight, atmospheric glow, etc. Because these lights are very weak, we call them night low light.
These weak lights reflect weaker light after shining on objects, which is difficult for human eyes to see, but low-light night vision devices can use image intensifiers to increase these reflected lights to hundreds of thousands of times, so that they can be seen by the naked eye. It does not need to emit infrared rays, so it is naturally safer than active infrared night vision devices. Moreover, it is small in size, light in weight and consumes less power. But it also has disadvantages: because its working principle is low-light enhancement, it is greatly affected by climatic conditions and does not work well in cloudy, smoky, foggy, dark and other environments.
In fact, people are almost always pursuing more perfect inventions, so they are willing to try many times and use different principles and materials to achieve the same effect. As early as the beginning of the 20th century, people were studying thermal imaging technology. In 1959, the University of Chicago in the United States developed the first forward-looking infrared thermal imager. By the 1970s, portable thermal imagers first appeared in the military field.
The so-called thermal imager is to realize the reception, conversion and imaging of infrared rays. Its working principle is that all objects with a temperature higher than absolute zero (-273.15℃) will actively radiate infrared rays, and the higher the temperature, the stronger the infrared radiation. Therefore, thermal imagers can perfectly capture everything that radiates infrared rays, and can see through camouflage, have strong concealment, and are not affected by climate and time. They are currently the most advanced night vision instruments in the world. Although the images of thermal imagers are not very clear, with the development of science and technology, thermal imagers will inevitably become more perfect.
The invention of night vision goggles is of extraordinary significance. It is a self-breakthrough achieved by humans based on the use of natural laws. It provides people with a pair of eyes that can see through the night, greatly improving work efficiency. Today, we widely use night vision goggles in reconnaissance, monitoring, driving, flying, maritime operations, field survival and other fields, so that night vision goggles can escort people's safety in countless dark nights.