Optical design of a 200 eV–2.5 keV cylindrical element monochromator for the 1.3-GeV storage ring of SRRC

Abstract

Separate focus-function mirrors in combination with a simple-scanning spherical/cylindrical grating are to be used for an extreme grazing-incidence beamline design in the photon energy range of 200 eV–2.5 keV at the ARC synchrotron radiation of the TBA lattice of SRRC. Three mechanically ruled gratings are used to cover the spectral wavelength range of the extreme VUV and soft x rays. Both the throughput and the resolution of this optical system have been carefully calculated and compromised against the grazing angle, arm length, grating size, etc. The proper parameters of the optical elements as well as their geometrical arrangements are proposed. A resolving power of at least 2000 is obtainable at the high-energy end of the spectrum around 2 keV. At the low-energy end, the resolving power can be as high as 8000, comparable to a grazing-incidence Rowland circle type of monochromator. The overall resolving power has been found to be superior to that of either the plane grating monochromator (PGM) or the 10-m toroidal grazing monochromator (TGM) in the same spectral wavelength range.