infrarøde

Infrarøde (infrared radiation) is the portion of the electromagnetic spectrum with longer wavelengths than visible light but shorter than microwave radiation. In Danish usage, the term refers to this range, which spans roughly from 0.75 micrometres to about 1000 micrometres (1 millimetre). It is commonly divided into near-infrared, mid-infrared, and far-infrared, with near-infrared closest to visible light and far-infrared closer to the microwave region.

All objects emit infrared radiation as a consequence of their temperature, a phenomenon described by Planck’s law. The intensity and spectral distribution depend on temperature, so warmer objects emit more infrared and at shorter wavelengths. This property makes infrared useful for thermal imaging and temperature measurement, even in darkness or through obscurants like smoke or fog. Infrared detectors include bolometers, thermopiles, and semiconductor-based photodiodes, with different materials optimized for various subranges of the spectrum. Some infrared detectors require cooling to reduce noise, while others are uncooled and used in consumer and industrial applications.

Applications of infrarøde technologies are broad. Thermal imaging is used in medicine, building inspection, firefighting, and security. In astronomy, infrared observations reveal cool and dust-enshrouded objects not visible in other bands. Infrared spectroscopy supports chemical analysis and environmental monitoring. Infrared communication, including remote controls and some wireless links, uses specific infrared wavelengths. Atmospheric absorption by water vapor and carbon dioxide shapes which infrared bands are practical for open-air use. The term reflects both scientific and practical aspects of working with this non-visible portion of the spectrum.