Patent Number: 051270285
Section: abstract

A diffractor for energetic electromagnetic radiation has diffracting planes oriented parallel to the surface of steps which have a doubly curved surface. The steps are configured so that the resulting diffractor approximates the Johansson geometric conditions in the plane of the focal circle of radius r. The steps are additionally curved in a direction perpendicular to the focal circle in order to provide for satisfying Bragg's law for diffraction over the maximum area of the diffractor. The curvature of the planes perpendicular to the focal circle corresponds to rotating the stepped approximation to the Johansson geometry about an axis passing through the source and image points. The diffracting materials are thin sheets of doubly curved single crystal stacked together, thin sheets of single crystal material mounted on the doubly curved surfaces of the steps, pieces or flakes of single crystal material mounted on the doubly curved surfaces of the steps or layered synthetic microstructures deposited on the doubly curved surfaces of the steps.