Design of a new soft X-ray double crystal monochromator beamline, BL-13

A new soft X-ray double crystal monochromator beamline is designed and will be constructed at BL-13. Special care is paid for the degree of parallelism of the beam and the beam size at the focal point. We propose to use two toroidal mirrors, one for producing a parallel beam and another for focusing the beam at the sample position. Although a toroidal mirror is not ideal to produce a parallel beam, the ray-tracing simulation clearly indicates that the quasi-parabolic mirror (1:∞ focusing) produces a nearly parallel beam comparable with a parabolic mirror. Another quasi-parabolic mirror (∞:1) focuses the beam at the sample position in a size of 1 mm H x 1 mm V . The designed beamline will be constructed by the end of 2013 and be open to users in the next fiscal year.