echelette grating

echelette grating

[¦esh·ə¦let or ¦āsh¦let ‚grād·iŋ]
(spectroscopy)
A diffraction grating with coarse groove spacing, designed for the infrared region; has grooves with comparatively flat sides and concentrates most of the radiation by reflection into a small angular coverage.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.