Bidimensional focusing of x rays by refraction in an edge

When an x-ray beam passes through the tip of a triangular prism, i.e., an edge, it undergoes two consecutive refraction processes. This will also happen when the incident beam is not perpendicular to the tip but when the beam progresses at a very small inclination to it. It will be shown that in such a condition, when both interfaces adjacent to the tip have concave surfaces, decoupled focusing in two orthogonal directions can be introduced in the transmitted x-ray beam. The limitations for this application are discussed, and focusing of x rays to spots with diffraction limited sizes of the order of 100 nanometers is found to be feasible. The feasibility of bidimensional focusing by use of such a device was experimentally verified. (C) 2014 Optical Society of America