HIGH-ENERGY X-RAY PHASE-CONTRAST MICROSCOPY USING A CIRCULAR BRAGG-FRESNEL LENS

High energy X-ray phase contrast microscopy based on Bragg-Fresnel opt ics with submicrometer resolution was demonstrated. An X-ray image of a free-standing gold grid was observed at 9.5 keV using a circular Bra gg-Fresnel lens in backscattering geometry. The fine 0.5 mu m gold gri d was clearly seen not only in the open areas of the supporting mesh b ut also underneath the 3 mu m bars. A contrast of more than 20% was me asured. 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.