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Figure 5
Tuning behavior of the three spectrometer designs. (a) The change in detector distance r2 as a function of energy required to zero aberrations up to the coma term. Since the elliptical cylinder and sagittal collimating VFM form a nearly perfect virtual image, the focal distance is essentially constant with energy. For the toroid VFM, the change in distance is still quite minimal, requiring only a few millimetres change to stay in focus. (b) The changes to α and β required to zero the aberrations up to the coma term. Here we plot α and β as grazing angles. Note that the behavior between the elliptical cylinder/sagittal collimating and toroid VFM are quite different. (c) The first-order diffraction efficiency for the blazed 1300 mm−1 grating. Due to the different angular tuning behavior of the elliptical cylinder/sagittal collimating and toroid VFM design, the diffraction efficiency is different. (d) The nominal resolving power, which again varies between the cases due to the different angular tuning of the grating.

Journal logoJOURNAL OF
SYNCHROTRON
RADIATION
ISSN: 1600-5775
Volume 33| Part 4| July 2026| Pages 1005-1015
https://doi.org/10.1107/S1600577526005564
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