infrapunä

Infrapunä is the term used in certain Nordic languages to denote infrared radiation, the portion of the electromagnetic spectrum with wavelengths longer than those of visible light. Infrared radiation extends roughly from 700 nanometers to 1 millimeter and is commonly divided into near-, mid-, and far-infrared bands. It is produced by thermal emission from objects as a function of temperature, and many everyday objects emit infrared even when they are not visibly hot.

Humans cannot see infrared with the naked eye, but it can be detected by specialized sensors, cameras, and materials designed for IR detection. Infrared radiation is widely used in imaging (thermal imaging and night vision), spectroscopy, environmental sensing, and communications. Infrared heaters use IR radiation to transfer heat; remote controls transmit information using near-infrared light; fiber-optic systems can use infrared wavelengths for data transmission.

Detectors vary by wavelength: near-infrared uses InGaAs or silicon-based photodiodes; mid- and far-infrared rely on materials such as InSb, HgCdTe, or bolometers. Advances in uncooled infrared cameras and low-cost IR LEDs have expanded consumer applications.

History: infrared radiation was discovered by William Herschel in 1800 when he demonstrated heat beyond the red end of the visible spectrum, naming the region infrared. The concept has since become central in science and technology.

Safety: infrared exposure can cause thermal injury at high intensities; appropriate shielding and eye protection are advised when working with powerful IR sources.

See also: infrared spectroscopy, thermal imaging, remote sensing, infrared communication.