What is NIR/SWIR/MWIR/LWIR/FIR Spectral Range?

Herschel was the first person to discover the existence of infrared ray.

As early as February 1800, he used prism to study the visible spectrum. Herschel found that he could put the thermometer outside the red end of the spectrum and detected unknown invisible spectra, which were hotter than any visible light.

Today, we call this invisible spectrum “infrared” radiation, which is located between the visible light and microwave frequencies of the electromagnetic wave spectrum. The part with a wavelength of 0.78 ~ 2.0 microns is called near infrared, and the part with a wavelength of 2.0 ~ 1000 microns is called thermal infrared. When infrared ray is transmitted on the surface, it will be absorbed by atmospheric components (especially H2O, CO2, N2O, etc.), and its intensity will decrease significantly, only in medium wave 3um~ 5um and long wave 8um ~ 12um The two bands have good transmission, which is commonly known as the atmospheric window. Most infrared thermal imagers detect these two bands, calculate and display the surface temperature distribution of objects. In addition, due to the poor penetration ability of infrared to a large part of solid and liquid substances, infrared thermal imaging detection is mainly to measure the infrared radiation energy of the object surface.

Name Abbreviation CIE/DIN Wavelength
Near Infrared NIR IR-A (0.78 … 1.4)
Short Wave Infrared SWIR IR-B (1.4 … 3.0)
Medium Wave Infrared MWIR IR-C (3.0 … 8.0)
Long Wave Infrared LWIR IR-C (8.0 … 15.0 (50.0))
Far Infrared FIR IR-C (15.0 (50.0) … 1,000.0)

Post time: Apr-15-2022