As we all know, infrared night vision devices play an important role in military warfare. Do you know how night vision devices can see clearly in dark environments?

Current night vision devices are mainly divided into active infrared night vision devices, thermal imaging infrared devices and low-light night vision devices. Active infrared night vision devices use photoelectric conversion technology to irradiate the emitted infrared beam to the target, and then convert the infrared image reflected by the target into a visible light image. Although there is still weak light in the dark night, infrared night vision devices can convert these light that cannot be seen by the human eye into clearer and richer ones. They are often used in customs, border defense and night patrols.

Active infrared night vision devices

Working principle of active infrared night vision devices

However, infrared night vision devices have a fatal disadvantage, that is, the emitted infrared light can be easily detected by the enemy's infrared detection device, so thermal imaging infrared devices are developed on this basis.

Thermal imaging infrared device

Thermal imaging infrared device is also called thermal imager. Its working principle is to convert the infrared radiation on the surface of an object into a visible image through the temperature difference between the heat emitted by the object and the background. Since the thermal imager has the function of measuring temperature, the grayscale image can be pseudo-colored by using the characteristics of the distribution of objects on the surface of the object.

Working principle of thermal imaging infrared device

In simple terms, it converts the invisible infrared energy emitted by the object into a visible thermal image. Different colors represent different temperatures of the measured object, and the thermal imager is not affected by obstacles such as smoke and trees. It can work day and night. It is the most advanced night vision observation instrument currently mastered by humans, but it is currently only used in the military due to its high price.

The imaging of low-light night vision device mainly relies on a component called image intensifier. When weak natural light shines on the target surface, the image intensifier can enhance the weak target, and the enhancement ability can even be magnified to hundreds of thousands of times. It can be said that the low-light night vision device is a special telescope with a built-in intensifier. At present, it is most widely used in military criminal investigation and night monitoring. Unfortunately, the low-light night vision device can only be used at night and cannot be used normally during the day.

Low-light-level night vision goggles

Now that you know the working principles of the three commonly used night vision goggles, do you know the difference between night vision goggles and the surveillance cameras we usually use?

In fact, security monitoring uses infrared lights to fill in the light, and then uses cameras to capture the images. It is mainly used to monitor the flow of people, and the monitoring effect is not particularly ideal in night environments. Night vision goggles use infrared lights emitted by objects to form images, not light sources to fill in the light, and also use detection movements and thermal imaging lenses. They are more expensive and are mainly used in the military field.