High-resolution projection image reconstruction of thick objects by hard x-ray diffraction microscopy

Abstract

Hard x-ray diffraction microscopy enables us to observe thick objects at high spatial resolution. The resolution of this method is limited, in principle, by only the x-ray wavelength and the largest scattering angle recorded. As the resolution approaches the wavelength, the thickness effect of objects plays a significant role in x-ray diffraction microscopy. In this paper, we report high-resolution hard x-ray diffraction microscopy for thick objects. We used highly focused coherent x rays with a wavelength of $\ensuremath{\sim}0.1\text{ }\text{nm}$ as an incident beam and measured the diffraction patterns of a $\ensuremath{\sim}150\text{-nm}$-thick silver nanocube at the scattering angle of $\ensuremath{\sim}3\ifmmode^\circ\else\textdegree\fi{}$. We observed a characteristic contrast of the coherent diffraction pattern due to only the thickness effect and collected the diffraction patterns at nine incident angles so as to obtain information on a cross section of Fourier space. We reconstructed a pure projection image by the iterative phasing method from the patched diffraction pattern. The edge resolution of the reconstructed image was $\ensuremath{\sim}2\text{ }\text{nm}$, which was the highest resolution so far achieved by x-ray microscopy. The present study provides us with a method for quantitatively observing thick samples at high resolution by hard x-ray diffraction microscopy.