etalon

[ eyt-l-on ]
/ ˈeɪt lˌɒn /

noun Optics.

an interferometer consisting of two glass plates that reflect approximately half of each ray of light incident upon them and that are separated by a small, fixed distance: used to compare wavelengths and to study atomic spectra.

Origin of etalon

1900–05; < French; Middle French estalon standard, derivative of Old French estal place < Germanic; see stall1

British Dictionary definitions for etalon

etalon
/ (ˈɛtəˌlɒn) /

noun

physics a device used in spectroscopy to measure wavelengths by interference effects produced by multiple reflections between parallel half-silvered glass or quartz plates

Word Origin for etalon

C20: French étalon a fixed standard of weights and measures, from Old French estalon; see also stallion