PerkinElmer AVIO 500, Руководство по оборудованию и обслуживанию для клиентов

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How the Echelle Spectrometer and SCD Work
passes through the slit, it is collimated by the parabolic mirror and sent to the
echelle grating.
The echelle grating is a coarse grating with a ruling density of 79 lines/mm. It is
precisely ruled with broad flat grooves. The width of each groove is twice the
height. Because of this groove shape, this grating is often compared to a series of
steps, with diffraction occurring off the steep side of the steps. This produces
multiple, overlapping diffraction orders with very good efficiency in each of the
orders. By contrast, non-echelle-based spectrometers use an echellette grating,
which has a high ruling density. The echelle grating is optimized through the blaze
angle to have a maximum efficiency in one of its lower orders.
Figure 3-9. Echelle grating (a) and Echellette grating (b)
Another advantage of the echelle grating is that it has high dispersion
characteristics since it is used in the
higher diffraction orders. This means that the
Item Description
1 A
2 Incident and Diffracted Rays
3 B
4 Incident Ray
5 Diffracted Ray
1
2
3
4 5