Infrapunakiirgus

Infrapunakiirgus, literally “infrared glow” in Finnish, is a term used to describe the emission of infrared radiation by objects at nonzero temperatures, or more broadly the infrared-visible appearance of such radiation when observed with infrared instrumentation. The word combines infrapuna (infrared) and kiirgus (glow or emission). In physics, infrared glow arises from thermal radiation that follows Planck’s law: as temperature increases, an object’s emission shifts toward the infrared and the radiated power grows, producing a measurable glow in the infrared spectrum. In practice, infrapunakiirgus is detected with infrared cameras, bolometers, or spectrometers and is used to assess temperature distributions and heat transfer.

In technology and research, the concept underpins infrared thermography, industrial inspection, and medical thermography, where infrared glow maps reveal defects, insulation performance, or tissue temperatures. In astronomy, infrared glow from celestial objects traces warm dust, protostars, and evolved stars, enabling studies of star formation and galactic structure.

The infrared bands are typically categorized into near-infrared (about 0.75–5 μm), mid-infrared (5–25 μm), and far-infrared (25–1000 μm). Detectors include mercury cadmium telluride (HgCdTe) and indium antimonide (InSb) devices, as well as bolometer arrays.

See also Infrared radiation, Thermography, Blackbody radiation, Spectroscopy.