Infrared thermal imaging uses photoelectric technology to detect the infrared specific band signal of thermal radiation of objects. The signal is converted into images and graphics that can be resolved by human vision, and the temperature value can be further calculated. Infrared thermal imaging technology enables people to transcend the visual barrier, so that people can "see" the temperature distribution on the surface of objects.
If the surface temperature of an object exceeds absolute zero, it will radiate electromagnetic waves. With the change of temperature, the radiation intensity and wavelength distribution characteristics of electromagnetic waves will also change. Electromagnetic waves with wavelengths ranging from 0.75 μ m to 1000 μ m are called "infrared", while the "visible light" visible by human vision ranges from 0.4 μ m to 0.75 μ M.
The wavelength of 0.78 ~ 2.0 μ m is called near infrared, and the wavelength of 2.0 ~ 1000 μ m is called thermal infrared. When the infrared ray is transmitted on the surface, it will be absorbed by the atmospheric components (especially H2O, CO2, CH4, N2O, O3, etc.) and its intensity decreases obviously. Only in the medium wave band of 3 μ m ~ 5 μ m and the long wave band of 8 ~ 12 μ m, the infrared ray has better transmission, which is generally called atmospheric window Most of the infrared thermal imagers detect these two bands, calculate and display the surface temperature distribution of the object. In addition, due to the poor penetration ability of infrared ray to most solid and liquid substances, infrared thermal imaging detection is mainly to measure the infrared radiation energy of the object surface.
Camera imaging to get photos, television camera imaging to get television images, are visible light imaging. In nature, all objects can radiate infrared rays. Therefore, different infrared images can be obtained by measuring the infrared difference between the target itself and the background by using the detector. The image formed by thermal infrared is called thermal map.