Classification and difference of infrared lens

The difference between short wave infrared, near infrared, medium wave infrared and long wave infrared

Near Infrared (NIR): Wavelength between 0.75-1.4 microns, defined by the absorption of water, usually used in optical fiber communication due to the low attenuation rate in silica glass. Wavelengths in this region are very sensitive to image enhancement. For example, night vision devices such as night vision goggles are included.

Short Wavelength Infrared (SWIR): 1.4-3 microns, water absorption increases significantly at 1,450 nanometers. 1,530 to 1,560 nm is the main spectral region that dominates long-distance communications.

Mid-wavelength infrared (MWIR) is also called mid-infrared: the wavelength is 3-8 microns. Passive infrared heat-seeking missile technology is designed to use the atmospheric window in the 3-5 micron band to work, and the homing of the infrared marking of the aircraft is usually aimed at the plume emitted by the aircraft engine.

Long wavelength infrared (LWIR): 8-15 microns. This is the area of "thermal imaging", where sensors in this band can obtain a complete passive image of heat emissions without the need for additional light or external heat sources such as the sun, moon or infrared lights.

NIR and SWIR are sometimes referred to as "reflected infrared," while MWIR and LWIR are sometimes referred to as "thermal infrared."