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Proceedings Paper

Echelle Efficiency And Blaze Characteristics
Author(s): M. Bottema
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Paper Abstract

On the basis of a simple model for diffraction by the groove, we show that the efficiency of an echelle is high in the Littrow arrangement, but becomes markedly less if the angle of deviation between the incident and the diffracted beams is increased. We also show that the height and width of the spectral image change if the directions of incidence and diffraction are interchanged, but that the efficiency remains the same. In general, the direction of maximum efficiency does not coincide with the blaze direction, defined as the maximum of the envelope of the diffracted-light distribution function. The difference depends on the mode of operation of the spectrograph (scanned or stationary spectrum) and typically changes from a fraction of a degree at high orders in the UV to several degrees at low orders in the IR. Experimental evidence agrees qualitatively with these calculations, but a more refined diffraction model may be needed for a quantitative interpretation.

Paper Details

Date Published: 10 February 1981
PDF: 7 pages
Proc. SPIE 0240, Periodic Structures, Gratings, Moire Patterns, and Diffraction Phenomena I, (10 February 1981); doi: 10.1117/12.965652
Show Author Affiliations
M. Bottema, Ball Aerospace Systems Division (United States)


Published in SPIE Proceedings Vol. 0240:
Periodic Structures, Gratings, Moire Patterns, and Diffraction Phenomena I
C. H. Chi; E. G. Loewen; C. L. O'Bryan III, Editor(s)

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