Echelle diffraction grating

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Principle of operation of echelle spectrograph: G1 - echelle grid, G2 - separator (ordinary grid or prism), S - detector Spectral of the sun obtained using the echelle spectrograph

The echelle diffraction grating (from echelle frieze - staircase or ladder) is a kind of diffraction grating optimized for light gain in high spectral rows. It is made as a reflection type grid. On its surface there are stepped incisions spotted by a reflective metal layer whose width and height are chosen to produce a clear picture of high spectral rows for large angles of light. Since high spectral rows overlap considerably, for practical use of such a grid it is necessary to use an additional separator which can be a glass prism or a normal diffraction grating placed on the path of light reflected from the echelle grid. A grid of this kind is used, among others. in high-resolution astronomical spectrographs such as HARPS. Bibliography

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