Identification of infrared rays emitted by electric light sources and their range
Daylight and many other light sources contain near-infrared radiation in their spectra.
Infrared radiation from a light source converts into unwanted heat, reducing the luminous efficacy. Radiant flux is measured in watts, and irradiance is measured in watts per square meter. The International Commission on Illumination divides the most important infrared wavelength regions into the near-infrared (IR-A), from 780 to 1400 nm; the mid-infrared (IR-B), from 1.4 to 3 microns; and the far-infrared (IR-C), from 3 microns to 1 mm.