Simple design of varied-line-spacing plane grating monochromator for compact storage ring (HiSOR)

A varied-line-spacing plane grating monochromator (VLSPGM) using a converging beam has been designed for the bending-magnet beamline BL-6 of the compact racetrack-type storage ring, HiSOR. The monochromator is designed to cover the energy range of 200–1200 eV by using two gratings and to obtain high throughput even for a moderate-emittance ring. A resolving power of 4000 is expected at the photon energy of 400 eV. Both an incident light from the source point to the entrance slit of the monochromator and a monochromatic light from the exit slit to the sample position travel horizontally. This simple design makes the overall length of the beamline short within 11.5 m and the optical alignment of the beamline quite easy.