Ge. Ice et Cj. Sparks, CONICAL GEOMETRY FOR SAGITTAL FOCUSING AS APPLIED TO X-RAYS FROM SYNCHROTRONS, Journal of the Optical Society of America. A, Optics, image science,and vision., 11(4), 1994, pp. 1265-1271
We describe a method for simultaneously focusing and monochromatizing
x rays from a fan of radiation having as high as 15-mrad divergence in
one dimension. This geometry is well suited to synchrotron radiation
sources at magnifications of 1/5 to 2 and is efficient for x-ray energ
ies between 3 and 40 keV (0.48 and 6.4 fJ). The method uses crystals b
ent to part of a cone for sagittal focusing and permits the collection
of a larger divergence with less mixing of the horizontal into the ve
rtical divergence than is possible with x-ray mirrors. We describe the
geometry required for achieving the highest efficiency when a conical
crystal follows a flat crystal in a nondispersive two-crystal monochr
omator. At a magnification of 1/3, the geometry is identical to that o
f a cylindrical focusing design described previously [Nucl. Instrum. M
ethods 172, 237 (1980)]. A simple theoretical calculation is shown to
agree well with ray-tracing results. Minimum aberrations are observed
at magnifications near 1. Applications of the conical focusing geometr
y to existing and future synchrotron radiation facilities is discussed
.