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prettygoodwordetalon (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.
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.
