far infrared (automotive) (FIR)
Infrared is divided into different ranges: Far Infrared(FIR), Long Wavelength Infrared (LWIR) Mid Wavelength Infrared (MWIR), Short Wavelength Infrared( SWIR) and Near Infrared( NIR).
The individual infrared ranges have different wavelengths and are used with their properties in a wide variety of technical applications. For example, in night vision devices or automotive technology for distance measurements.
Far-infrared comprises by far the largest infrared range and has the longest wavelengths. The wavelengths of far infrared vary in the specifications. Generally, the wavelength range for Far Infrared is specified between 15 µm and 1 mm, according to DIN 5031 it is wavelengths between 5.0 µm and 1 mm. The corresponding frequency range is approximately between 300 GHz and 30 THz, whereby the lower frequency range can still be assigned to the microwave.
Far-infrared is absorbed by molecular motions in gases and liquids, so also by humidity. However, there are wavelengths in the entire far-infrared range that are used for remote measurements and in astronomy.