Infrared spectrum region of infrared remote sensing

In the electromagnetic spectrum, the wavelength range of 0. 76 to 1000 microns is usually called the infrared spectrum region. Among them, it is divided into near infrared (0.76 ~ 3.0 microns), mid infrared (3.0 ~ 6.0 microns), far infrared (6.0 ~ 15.0 microns) and ultra-far infrared (15.0 ~ 1000 microns). Near infrared and mid-infrared can also be collectively called reflected infrared; far infrared is called thermal infrared (8 to 14 microns) or emitted infrared. Although the infrared spectrum is very broad, there are actually only a few infrared "windows" available due to atmospheric absorption. Commonly used infrared bands include near and mid-infrared 0.3-1.3 microns, 1.5-1.8 microns, 2.0-2.6 microns, 3.0-3.6 microns, 4.2-5.0 microns and far-infrared 7.0-15.0 microns. The near-infrared band is mainly used for optical photography, such as infrared or color infrared photography, which can only work during the day; it is also used for multi-band photography or multi-band scanning. Far infrared (thermal infrared) is mainly used for night-time infrared scanning imaging because it is radiated by ground objects themselves. Infrared remote sensing is widely used in military reconnaissance, detecting volcanoes, geothermal, groundwater, soil temperature, identifying geological structures and pollution monitoring, but it cannot work in clouds, rain, or fog.