X-ray wavefront sensing and optics metrology using a microfocus x-ray grating interferometer with electromagnetic phase stepping

Abstract

A metrology method of x-ray optical elements based on an electromagnetic phase stepping x-ray grating interferometer with high slope accuracy is presented in this study. The device consists of an x-ray tube, a phase grating [Formula: see text] for modulating the incoming wavefront, and an absorption grating [Formula: see text] as a transmission mask to produce a broader moiré pattern for the x-ray camera. The focal spot of the microfocus x-ray source is shifted by a magnetic field from a solenoid coil. Electromagnetic phase stepping analysis is used to obtain a pixel-wise map of the wavefront phase distortion to replace the traditional precision mechanical scanning system, improving stability, speed, accuracy, and flexibility. The x-ray grating interferometer can be used as a feedback tool for evaluating the quality of optical elements and detecting defects caused by the x-ray beam or the x-ray optical elements in ordinary laboratories and mirror-processing centers without the need of scheduling synchrotron beam time.