High energy X-ray phase contrast microscopy using a circular Bragg-Fresnel lens

High energy X-ray phase contrast microscopy based on Bragg-Fresnel optics with submicrometer resolution was demonstrated. An X-ray image of a free-standing gold grid was observed at 9.5 keV using a circular Bragg-Fresnel lens in backscattering geometry. The fine 0.5 μm gold grid was clearly seen not only in the open areas of the supporting mesh but also underneath the 3 μm bars. A contrast of more than 20% was measured. The theory of the image formation in partially coherent X-rays on a basis of Hopkins formula is considered. The application of phase contrast imaging for low-density materials is discussed.