What are the wavelength boundaries of infrared radiation?

The infrared radiation is the electromagnetic radiation where wavelengths are between 700 nanometres and 1 millimetre. Thus, it is located between the red limit of visible spectrum and the shortest microwaves.

Wavelength boundaries

However, taking into account the major applications of thermal sensors, the main considered spectral range is between 1 µm and 50 µm including 3 major sub spectral ranges corresponding to the atmosphere transmission windows:

  • 1 µm to 3 µm or Short Wave Infrared (SWIR) or band I
  • 3 µm to 5 µm or Middle Wave Infrared (MWIR) or band II
  • 8 µm to 14 µm or Long Wave Infrared (LWIR) or band III.