Hard X-ray Holographic Microscope for 3D Phase Reconstruction of Semitransparent Object

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Gabor and lens-less Fourier transform holographic microscopes have been developed for the purpose of (a) high-resolution phase-contrast imaging, (b) quantitative phase imaging, and (c) 3D phase reconstruction. A combination of the x-ray undulator source of SPring-8 and a high-resolution zone plate enabled us to make a secondary coherent source as small as 100 nm size. Then, a tantalum line and space pattern as fine as 100 nm could be resolved both Gabor and lens-less Fourier transform holography at 10 keV. This is the highest resolution that has been reported in hard x-ray holography. The image of the lens-less Fourier transform holography was edge-enhanced one because the central region of the hologram had to be blocked. For quantitative phase imaging, a lens-less Fourier transform holographic microscope with a double zone plate interferometer was newly developed. Not only the edge pattern but also the inside flat field of a tantalum pattern could be reconstructed. Using this optical system, projection data for 3D phase tomography could be recorded and the reconstruction is currently under way. A Zernike-type hard x-ray phase-contrast microscope was also developed at the Photon Factory. A tantalum line and space pattern as fine as 100 nm could be clearly resolved at 9 keV.To make a ID small x-ray source, total reflection from a limited mirror surface was also investigated. The reduction of the secondary source size was confirmed from the Gabor hologram of a gold wire illuminated with the reflected x-rays at 8 keV. This method can be used to make a small reference source of holography, the size of which determines the spatial resolution.