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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