An example of etalon is the equipment used to stabilize the wavelength of a laser.
Origin of etalon
- 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 Middle Dutch stael model, sample
From American Heritage Dictionary of the English Language, 5th Edition
- From French étalon (“measuring gauge, standard”).