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echelette

American  
[esh-uh-let, ey-shuh-] / ˌɛʃ əˈlɛt, ˌeɪ ʃə- /

noun

Spectography.
  1. a diffraction grating designed to reflect infrared radiation.


Etymology

Origin of echelette

< French échelette rack, equivalent to échelle ladder ( echelon ) + -ette -ette