Diffraction imaging for in-situ characterization of double-crystal x-ray monochromators

TL;DR

This paper introduces a diffraction imaging technique for in-situ, rapid assessment of double-crystal x-ray monochromator performance under heat load, linking wavefront distortions to crystal misorientation.

Contribution

It presents a novel diffraction imaging method for real-time characterization of crystal distortions in monochromators during operation.

Findings

The method accurately measures crystal misorientation.

It correlates wavefront distortions with thermal effects.

Provides insights into local crystal quality.

Abstract

Imaging of the Bragg reflected x-ray beam is proposed and validated as an in-situ method for characterization of 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 to results of finite element analysis. The imaging method offers an additional insight on the local intrinsic crystal quality over the footprint of the incident x-ray beam.