Definition of etalon in English:

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Pronunciation: /ˈɛtəlɒn/


A device consisting of two reflecting glass plates, employed for measuring small differences in the wavelength of light using the interference it produces.
Example sentences
  • The change in resonance frequency of the etalon measures the change in optical-path length.
  • We specialize in very large aperture etalons with diameters up to 150 mm.
  • Our products range from simple condenser lenses to precision etalons.


Early 20th century: from French étalon, literally 'standard of measurement'.

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