An echelle grating (from French échelle, meaning "ladder") is a type of diffraction grating characterised by a relatively low groove density, but a groove shape which is optimized for use at high incidence angles and therefore in high diffraction orders. Higher diffraction orders allow for increased dispersion (spacing) of spectral features at the detector, enabling increased differentiation of these features. Echelle gratings are, like other types of diffraction gratings, used in spectrometers and similar instruments. They are most useful in cross-dispersed high resolution spectrographs, such as HARPS, PARAS, and numerous other astronomical instruments.
Hello,
I am attempting to understand and simulate an echelle grating. The thorlabs website has somewhat of an explanation as to how they work...(here). In the echelle section they calculate the spacing in degrees of 600 nm and 605 nm at different orders. They use an example grating of 31.6...