Any object with a temperature above absolute zero radiates energy into outer space in the form of infrared light. The sensing technology that uses infrared radiation to measure relevant physical quantities is called infrared sensing technology.

Infrared sensor technology is one of the fastest developing technologies in recent years, infrared sensor has been widely used in aerospace, astronomy, meteorology, military, industrial and civil and other fields, playing an irreplaceable important role. Infrared, in essence, is a kind of electromagnetic radiation wave, its wavelength range is roughly 0.78m ~ 1000m spectrum range, because it is located in the visible light outside the red light, so named infrared. Any object with a temperature above absolute zero radiates energy into outer space in the form of infrared light. The sensing technology that uses infrared radiation to measure relevant physical quantities is called infrared sensing technology.

Photonic infrared sensor is a kind of sensor that works by using the photon effect of infrared radiation. The so-called photon effect refers to that when there is an infrared incident on some semiconductor materials, the photon flow in the infrared radiation interacts with the electrons in the semiconductor material, changing the energy state of the electrons, resulting in various electrical phenomena. By measuring the changes in the electronic properties of semiconductor materials, you can know the strength of the corresponding infrared radiation. The main types of photon detectors are internal photodetector, external photodetector, free carrier detector, QWIP quantum well detector and so on. The internal photodetectors are further subdivided into photoconductive type, photovolt-generating type and photomagnetoelectric type. The main characteristics of the photon detector are high sensitivity, fast response speed, and high response frequency, but the disadvantage is that the detection band is narrow, and it generally works at low temperatures (in order to maintain high sensitivity, liquid nitrogen or thermoelectric refrigeration is often used to cool the photon detector to a lower working temperature).

The component analysis instrument based on infrared spectrum technology has the characteristics of green, fast, non-destructive and online, and is one of the rapid development of high-tech analytical technology in the field of analytical chemistry. Many gas molecules composed of asymmetric diatoms and polyatoms have corresponding absorption bands in the infrared radiation band, and the wavelength and absorption strength of the absorption bands are different because of the different molecules contained in the measured objects. According to the distribution of the absorption bands of various gas molecules and the strength of absorption, the composition and content of gas molecules in the measured object can be identified. Infrared gas analyzer is used to irradiate the measured medium with infrared light, and according to the infrared absorption characteristics of various molecular media, using the infrared absorption spectrum characteristics of gas, through spectral analysis to achieve gas composition or concentration analysis.

The diagnostic spectrum of hydroxyl, water, carbonate, Al-OH, Mg-OH, Fe-OH and other molecular bonds can be obtained by infrared irradiation of the target object, and then the wavelength position, depth and width of the spectrum can be measured and analyzed to obtain its species, components and ratio of major metal elements. Thus, the composition analysis of solid media can be realized.