Impact of Beam-Width on X-ray Phase-Contrast Imaging: A Simulation and Experimental Study

We addressed X-ray phase-contrast imaging (XPCI), suitable for imaging low density bio-organic, polymer and fibric materials.The influence of the imaging conditions, including the X-ray beam-width, sample/source separation, sample/screen distance, edge's contour-line width and dielectric-constant of sample, on the XPCI fine structures was mathematically modeled, theoretically analyzed, numerically simulated and experimentally evaluated.The simulated results show that depending on the sample's alignment and properties, the X-ray beam-width has a major impact.The measured and simulated results were in good agreement.For example, too small a beam-width decreases the edge's contour-lines width due to strong spatial X-ray coherence and a beam-width too large reduces the contrast of edge's contour-line.Hence the fine structures can be well observed with a moderate or optimized X-ray beam-width.We suggest that X-ray beam-width should be optimized according to the dielectric constant and alignment of a specific sample.