
13.2.
Diffraction Grating; Basic Relations 323
150
mm.
This resolution is sufficient for this mode where the plate factor P is
typically about 150 A/mm.
As we show in Section 13.2, the resolution of
a
prism is low compared to what
is possible with a grating large enough to accept the same beam diameter. For this
reason, prisms are little used as primary dispersing elements in slit spectrometers,
having been largely replaced by gratings. Prisms are, however, often used as
cross-dispersers in spectrometers that use gratings for the primary dispersion. For
the objective mode, a prism is more efficient than a grating, for reasons made
clear whe ...