A device consisting of two reflecting glass plates, employed for measuring small differences in the wavelength of light using the interference it produces.
- ‘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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