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15.
Plane Grating Spectrometers
E
^
Fig. 15.14. Schematic layout of intermediate optics for white-pupil spectrometer design.
Dispersed light from the echelle (E) is recollimated by the Ml, M2 mirror pair and the pupil at the
echelle is reimaged at the white pupil (WP).
15.5.e. ECHELLE DESIGN EXERCISE
To illustrate some of the considerations that go into the design of an echelle
spectrometer, we take some specific parameters and determine the characteristics
of the instrument and spectrum format. The assumed parameters include
a telescope diameter Z) = 4m and an R-2 (3 = 63.5°) echelle with 31.6
grooves/mm used at 0 = 5°. We aim for a syste ...