Far infrared

Far infrared (FIR) or long wave refers to a specific range within the infrared spectrum of electromagnetic radiation. It encompasses radiation with wavelengths ranging from 15 μm (micrometers) to 1 mm, which corresponds to a frequency range of approximately 20 THz to 300 GHz. This places far infrared radiation within the CIE IR-B and IR-C bands.^[1] The longer wavelengths of the FIR spectrum overlap with a range known as terahertz radiation.^[2] Different sources may use different boundaries to define the far infrared range. For instance, astronomers often define it as wavelengths between 25 μm and 350 μm.^[3] Infrared photons possess significantly lower energy than photons in the visible light spectrum, with tens to hundreds of times less energy.^[4]

^ Byrnes, James (2009). Unexploded Ordnance Detection and Mitigation. Springer. pp. 21–22. ISBN 978-1-4020-9252-7.
^ Glagoleva-Arkadiewa, A. (1924). "Short electromagnetic waves of wave-length up to 82 Microns". Nature. 2844 (113): 640. Bibcode:1924Natur.113..640G. doi:10.1038/113640a0.
^ "Near, mid and far-infrared". Caltech Infrared Processing and Analysis Center. California Institute of Technology. Archived from the original on 2012-05-29. Retrieved 2013-01-28.
^ Gregory Hallock Smith (2006), Camera lenses: from box camera to digital, SPIE Press, p. 4, ISBN 978-0-8194-6093-6

[Byrnes-1] Byrnes, James (2009). Unexploded Ordnance Detection and Mitigation. Springer. pp. 21–22. ISBN 978-1-4020-9252-7.

[Glagoleva-2] Glagoleva-Arkadiewa, A. (1924). "Short electromagnetic waves of wave-length up to 82 Microns". Nature. 2844 (113): 640. Bibcode:1924Natur.113..640G. doi:10.1038/113640a0.

[caltech-3] "Near, mid and far-infrared". Caltech Infrared Processing and Analysis Center. California Institute of Technology. Archived from the original on 2012-05-29. Retrieved 2013-01-28.

[4] Gregory Hallock Smith (2006), Camera lenses: from box camera to digital, SPIE Press, p. 4, ISBN 978-0-8194-6093-6

[1]

[2]

[3]

[4]