SWIR is the short form for Short Wave Infrared, which is light invisible to human eyes between the wavelength range from 900nm to 1700nm. Together with Medium Wave Infrared (MWIR) and Long Wave Infrared (LWIR), the three wavelengths constitute the infrared wavelength. SWIR can not be seen with human eyes, but it has excellent sensitivity, as well as the ability to penetrate through fog, smog, cloud, and haze.