infraroten

Infrared radiation, commonly referred to as infrared (IR), is electromagnetic radiation with wavelengths longer than visible light and shorter than microwave radiation, typically from about 700 nanometers to 1 millimeter. The name infrarot derives from the German term for "below red."

Infrared is subdivided into near-infrared (0.7–1.4 μm), mid-infrared (1.4–5 μm), and far-infrared (5–1000 μm). Objects emit infrared as a function of temperature, described by blackbody radiation; as temperature rises, the peak emission shifts to shorter wavelengths (Wien's law).

Detection and imaging rely on measuring thermal radiation. Detectors include bolometers and pyroelectric sensors, as well as InGaAs photodiodes for near-infrared and mercury cadmium telluride (HgCdTe) for mid- and long-wave infrared. Infrared cameras translate radiation into temperature or brightness images and are used across science and industry.

Applications span thermal imaging in medicine and industry, night-vision systems, building inspection, astronomy, and spectroscopy for chemical analysis. Infrared spectroscopy probes molecular vibrations, enabling identification of minerals, organics, and gases.

Atmospheric transmission is affected by water vapor and CO2, producing absorption bands that limit IR propagation, but several atmospheric windows exist, notably around 0.8–1.0 μm, 3–5 μm, and 8–14 μm. Infrared is non-ionizing and generally safe, though intense sources can cause heating.

The discovery of infrared radiation is attributed to William Herschel in 1800, who demonstrated a temperature increase beyond the visible red end of the spectrum by using a prism and thermometers.