Infrared rays

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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Synonym(s)

Infrared radiation; IR; IRA; IRB; IRC; IR radiation; Ultrarot radiation

History
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Friedrich Wilhelm Herschel around 1800

Definition
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Electromagnetic waves in the spectral range between visible light and longer-wave terrahertz radiation. Infrared radiation is a part of thermal radiation. The spectral range between 780 nm and 1000,000 nm is called infrared. About 43% of the solar radiation reaching the earth's surface can be assigned to the IR spectrum.

Classification
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  • The spectral range is divided as follows:
    • near infrared (NIR): Short-wave IR-radiation which directly follows the visible (red) range. Wavelengths: 780 nm to 1.400 µm
    • mid infrared (MIR): Wavelengths: 1.4-50 µm.
    • far infrared (FIR): long wave IR radiation. Wavelength: 50 µm to 1.0 mm.
  • According to DIN it is divided as follows:
    • IRA: Wavelength: 0.7-1.4 µm.
    • IRB: Wavelength: 1,4-3,0 µm
    • IRC: Wavelength: > 3.0 µm up to 1.0 mm. This spectral range thus includes the mid (MIR) as well as the far infrared (FIR).

General information
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Broadband IR sources are thermal radiators such as incandescent lamps and radiant heaters. Selective emitters are the incandescent lamp or also high-pressure gas discharge lamps and also infrared LEDs. Infrared lasers (semiconductor lasers, Nd:YAG lasers,CO2 lasers) serve as monochromatic, coherent sources. Thermal detectors (thermocouples or bolometers) are suitable for detecting IR radiation of all wavelengths.

Complication(s)
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Infrared radiation causes erythema on the skin, the intensity and extent of which depends on the wavelength and energy of the radiation. For example, after IR-C irradiation an initially homogeneous, later reticular erythema is found which can still be detected several hours after radiation exposure (see also Erythma e calore).

Note(s)
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In medicine, heat radiation from radiant heaters (ceramic infrared radiators with long-wave IR radiation, red light lamps, which primarily emit near IR) are used for local treatment of inflammation. Infrared radiation is also frequently used in medicine in the form of lasers. It is possible that IR radiation of the skin can lead to chronic damage; premature aging of the skin is certain; the extent to which the development of carcinoma is promoted is still a matter of speculation. With water-cooled infrared radiators(wIRA principle) the heat development in the tissue is reduced so that higher energy doses are applicable (e.g. for the treatment of vulgar warts).

Literature
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  1. Arrington JH et al (1979) Thermal keratoses ans squamous cell carcinoma in situ associated with erythema ab igne. Arch Dermatol 115: 1226-1228
  2. Lee JH et al (2006) Effects of infrared radiationon skin photo-aging and pigmentation. Yonsei Med J 47: 485-490
  3. Meffert H et al (2008) The infrared erythema. Act Dermatol 34: 119-123
  4. Piazena H et al (2014) Physical and photobiological principles of prophylactic and therapeutic infrared applications. Act Dermatol 40:335-339

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Last updated on: 29.10.2020