Infrared radiation (IR) or the term infrared alone refers to energy in the region of the electromagnetic radiation spectrum at wavelengths longer than those of visible light,but shorter than those of radio waves. Correspondingly, the frequencies of IR are higher than those ofmicrowaves, but lower than those of visible light.
Scientists divide the IR spectrum into three regions. Thewavelengths are specified in microns (symbolized µ, where 1 µ = 10-6 meter)or in nanometers (abbreviated nm, where 1 nm = 10-9 meter = 0.001 µ). The near IR band contains energy in the range of wavelengths closest to thevisible, from approximately 0.750 to 1.300 µ (750 to 1300 nm). The intermediateIR band (also called the middle IR band) consists of energy in the range1.300 to 3.000 µ (1300 to 3000 nm). The far IR band extends from 2.000 to14.000 µ (3000 nm to 1.4000 x 104 nm).
Infrared is used in a variety of wirelesscommunications, monitoring, and control applications. A few of the applications include home-entertainment remote-control boxes, wireless local area networks, links between notebook computers and desktop computers, cordless modems, intrusion detectors, motion detectors, and fire sensors