Prefocusing optics for soft-x-ray synchrotron-radiation monochromators.

We present a mirror system to be used for the prefocusing optics of soft-x-ray monochromators using synchrotron radiation from a bending magnet source. The system consists of a cylindrical and a toroidal mirror arranged coplanarly. It can be made, by proper selection of the curvature radii of the mirrors, free of astigmatic coma. The design method is described in detail; the system is evaluated by exact ray-tracing calculations. Also given is a design example of the prefocusing optics in a soft-x-ray synchrotron radiation be aniline.