What is the principle of temperature measurement by infrared thermal imaging camera?

In nature, any object with a temperature greater than absolute zero (-273°C) can radiate infrared rays, which together with visible light, ultraviolet rays, X-rays, gamma rays, cosmic rays and radio waves, constitute A complete and continuous electromagnetic spectrum.

So infrared ray has a wavelength between 0.76μm and 1000μm, which is non-visible light with a longer wavelength than red light.

However, infrared rays in different bands have different characteristics and therefore have different applications, such as infrared remote control, infrared communication, infrared photography, infrared physiotherapy, etc. Among them, thermal imaging is between specific wavelengths.

Thermal imaging converts invisible infrared radiation into visible thermal images, and can reflect the temperature distribution of the target surface.

Different objects or even different parts of the same object have different radiation capabilities and their reflection of infrared rays. Using the difference in radiation between the object and the background environment as well as the difference in radiation from each part of the scene itself, infrared thermal imaging can present the radiation fluctuations of each part of the scene, thereby showing the characteristics of the scene.