etalon

[prettygoodword]

etalon (AYT-l-on) - n., an interferometer with two parallel partially silvered glass plates at a fixed distance apart, so that they reflect approximately half of each ray of light incident upon them, used for fine-structure analysis of spectrum lines.


Also called a Fabry–Pérot interferometer. Here's a schematic showing how (bottom) how the multiple reflections interfere and (top) what the result looks like:


Thanks, WikiMedia!

Coined around 1900 from French étalon, standard measure (as in measuring gauge), from Middle French estalon/estelon, standard, from Old French estal, place, from an unclear Germanic root but probably the same one that gave us stall.

---L.

Comments

[med_cat]

Very interesting!

Do you know this word also exists in Russian (also from the French, I'm sure), with a different meaning?

[prettygoodword]

Nope! I had no idea.

[med_cat]

Hehe, we both learned something today, then :)


этало́н
Мужской род

Точный образец установленной единицы измерения.

Translate эталон to
noun

1. reference
2. standard

(also used figuratively)

:)