Article
Article
Dispersion (radiation)
Article By:
Buchroeder, Richard A. Optical Design Service, Tucson, Arizona.
Last reviewed:2014
DOI:https://doi.org/10.1036/1097-8542.200400
The separation, by refraction, interference, scattering, or diffraction, of acoustic and electromagnetic radiation or energy into its constituent wavelengths or frequencies. For a refracting, transparent substance, such as a prism of glass, the dispersion is characterized by the variation of refractive index with change in wavelength of the radiation. Refractive index () is defined as the ratio of the velocity of the radiation in free space (air at standard temperature and pressure for sound, and a vacuum for electromagnetic radiation) to the velocity in the substance in question. I. Newton used a small hole in a window shade and a glass prism (see illustration) to disperse sunlight into a visible spectrum, from violet through red. Using a second prism, he showed that no further decomposition of any of the spectral colors could be achieved. See also: Optical prism; Refraction of waves
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