etalon

From French étalon (“measuring gauge, standard”).

etalon (plural etalons)

1. An optical device containing parallel mirrors, used as a narrow band filter, often in laser design.
   • 2004, S. C. Gupta, Textbook On Optical Fiber Communication And Its Applications, page 153:

     It will be shown that the simple theory outlined in the preceding paragraph, which is applicable to single-plate etalons, can be used to predict the main features of the spectral curve of a multi element etalon.

   • 2006, Walter Koechner, Solid-State Laser Engineering, page 264:

     The laser output will be composed of longitudinal modes that fall inside the transmission band of the etalon, hence a narrowing of the laser line width is observed.

   • 2009, V. Rajendran, Engineering Physics, page 7.15:

     The next step of this experiment is to compare the etalon m₁m₂ (shortest length) with the etalon m₃m₄ (the next one). For this two etalons are arranged side by side as shown in Fig. 7.13a.

• Fabry-Pérot interferometer

• étalon language

• late on, tolane, lean-to, leanto

Borrowed from French étalon.

etalon

1. prototype, standard.

• Mirjejev, V. A., Usejinov, S. M. (2002) Ukrajinsʹko-krymsʹkotatarsʹkyj slovnyk [Ukrainian – Crimean Tatar Dictionary]‎^[1], Simferopol: Dolya, →ISBN
• “etalon”, in Luğatçıq (in Russian)

Borrowed from French étalon.

etalon n (plural etaloane)

1. standard