Diffraction imaging forin situcharacterization of double-crystal X-ray monochromators

Abstract

Imaging of the Bragg-reflected X-ray beam is proposed and validated as anin situmethod for characterization of the performance of double-crystal monochromators under the heat load of intense synchrotron radiation. A sequence of images is collected at different angular positions on the reflectivity curve of the second crystal and analyzed. The method provides rapid evaluation of the wavefront of the exit beam, which relates to local misorientation of the crystal planes along the beam footprint on the thermally distorted first crystal. The measured misorientation can be directly compared with the results of finite element analysis. The imaging method offers an additional insight into the local intrinsic crystal quality over the footprint of the incident X-ray beam.