1. Features of infrared thermal camera
All objects with a temperature above absolute zero (-273°C) in nature emit infrared rays . Infrared rays (or thermal radiation) are the most widespread radiation in nature. The atmosphere, smoke clouds, etc. absorb visible light and near-infrared rays, but are transparent to infrared rays of 3-5 microns and 8-14 microns. Therefore, these two bands are called the "atmospheric windows" of the infrared. Using these two windows, we can clearly observe the situation ahead in a completely dark night, or in a harsh environment filled with smoke and clouds. It is precisely because of this feature that infrared thermal imaging technology can be used in night surveillance for security and forest fire prevention monitoring systems.
2. Infrared thermal camera imaging
Infrared thermal imaging, the wavelength of visible light that our human eyes can perceive is: 0.38-0.78 microns . Usually we refer to electromagnetic waves longer than 0.78 microns as infrared rays. In nature, all objects radiate infrared rays, so using a detector to measure the infrared difference between the target itself and the background, different infrared images can be obtained, which are called thermal images. The infrared thermal image is that the human eye cannot directly see the surface temperature distribution of the target, and becomes a thermal image that represents the target surface temperature distribution that the human eye can see.
3. Infrared thermal camera technology
The infrared thermal imager uses infrared thermal imaging technology to detect the infrared radiation of the target object, and converts the temperature distribution image of the target object into a video image through photoelectric conversion, signal processing and other means. We call it an infrared thermal imager. Infrared thermal imagers can be divided into two categories : cooled and uncooled . The thermal sensitivity of the cooling type is high and the structure is complex. It is generally used for military purposes. Although the sensitivity of the non-cooling type is lower than that of the cooling type , its performance can meet most military applications and almost all civilian fields.
4. Infrared camera principle - classification
Divided into passive and active two categories, of which:
1) Passive infrared camera. Passive infrared camera technology mainly uses the principle of the object itself to radiate infrared rays. All substances with a temperature higher than zero degrees (-273°C) are constantly radiating infrared rays above zero degrees (-273°C). Imaging is performed by the infrared light emitted by the monitored object itself in the scene. Based on the temperature difference or thermal radiation difference between the target and the background or each part of the target, a thermal image is generated to find the target. On this basis, the thermal image can also be Converted into video images, the product is called an infrared thermal imaging camera.
2) Active infrared camera. It is mainly a night vision technology that actively emits infrared light to supplement the light and image the monitoring scene, and uses the infrared light reflected by the target to realize monitoring . Now there are two types of products: LED infrared and laser infrared. Through active illumination and radiation "illumination" of the scene and environment, use ordinary low-illuminance CCD black and white cameras or use "color during the day, automatically turn black and white at night" cameras or "infrared low-light cameras" to feel the infrared light reflected back from the surrounding environment , thereby Realize the night vision function.