Phase-contrast imaging method for estimating the local stoichiometry of a sample

Abstract

An imaging method for determining a parameter δ of real and imaginary parts of a sample complex optical index; the method using an X-ray source to illuminate the sample, a perforated grating arranged between the sample and the detector, and a signal processing unit; the method performing measurement while illuminating the sample, the X-rays reaching the detector forming a spot for each grating hole; for each measurement and for each grating hole, analysing the grating spot by determining a spot barycenter using a centroid-finding technique, determining an offset of the barycenter relative to a reference barycenter and determining a local phase variation via the offset of the barycenter, determining an amplitude of the X-rays forming the spot and determining a local attenuation relative to a reference amplitude, determining the parameter δ on the basis of the local phase variation, and determining the imaginary part β via the local attenuation.