In-line Phase Contrast In Synchrotron-Radiation Microradiography And Tomography

摘要

When used in microimaging, hard X rays from third-generation synchrotron radiation (SR) sources inevitably generate non-interferometric or "in-line" phase contrast. It is formed by the propagation of a distorted X-ray wavefront after the sample. In this paper, we discuss phase contrast and its properties in two altogether different experimental modes: First, in edge-enhanced microtomography, we show by phase-propagation simulations that local tomography is possible without special effort. The second part of the paper discusses phase contrast and phase artifacts in magnified X-ray imaging and tomography using refractive lenses. Here, the phase effects degrade resolution to a considerable extent. This part of the paper contains experimental results from the ESRF beamline ID 22 in the photon energy range around 20 keV that are compared to simulated images and to experimental results from conventional high-resolution microtomography. The experimental results show that coherence-degrading devices can reduce but not completely eliminate phase effects, and recent microtomography data gathered with an X-ray microscope still cannot beat conventional state-of-the-art high-resolution microtomography with micrometer resolution.