e·ta·lon
(ā′tə-lŏn′, ĕt′ə-)n. A type of interferometer in which incoming light is repeatedly refracted and reflected between two surfaces into multiple beams that are then focused together, causing self-interference of the light.
[French étalon, standard (of weight or a unit of measurement), reference point, etalon (in reference to the fixed widths between the two surfaces in the first such interferometers), from Old French estalon, standard, of Germanic origin; akin to Middle Dutch stael, model, sample.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
etalon
(ˈɛtəˌlɒn) n (General Physics) physics a device used in spectroscopy to measure wavelengths by interference effects produced by multiple reflections between parallel half-silvered glass or quartz plates
[C20: French étalon a fixed standard of weights and measures, from Old French estalon; see also stallion]
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