pepo: A program for the calculation of the reflectivity of cylindrically bent Laue crystal monochromators

pepo is a program for the calculation of the reflection profiles of cylindrically bent Laue crystal monochromators based on the Penning and Polder theory of x‐ray diffraction in slightly strained crystals. The creation of new wave fields as well as an anisotropic model for the crystal deformation has been added to the original theory. The program runs under the computing environment IDL and is widget based. The calculation of perfect flat crystal reflectivity curves in Bragg and Laue geometry using the formulas presented by Zachariasen is included. The agreement with experimental results is excellent, allowing the derivation of focal properties from the calculated reflectivity curves.