Design of a Holographically Recorded Plane Grating with a Varied Line Spacing for a Soft X-ray Grazing-Incidence Monochromator.

A new design concept is presented for a plane grating with a varied line spacing for the Monk-Gillieson mounting monochromator. A light path function including both a spherical mirror and a varied-line-spacing grating is defined to optimize groove parameters. Aspheric wavefront recording optics are utilized to fabricate a grating holographically. Ray-tracing results show that the varied-line-spacing grating eliminates aberrations significantly and affords a high resolving power as a total optical system of a soft X-ray grazing-incidence monochromator. The effects of errors in recording parameters and in the radius of the spherical mirror are described, and possible ways to compensate for these errors are discussed.