Two phase extraction methods which are based separately on phase-stepping and shifting curve are mainly used in phase-sensitive imaging in gating interferometry to determine the x-ray phase shift induced by an object in the beam. In this paper, the authors perform a full comparative analysis and present the main virtues and limitations of these two methods according to the theoretical analysis of the grating interferometry.
The hydrated shell of both Fe2＋ and Fe3＋ aqueous solutions are investigated by using the molecular dynamics （MD） and X-ray absorption structure （XAS） methods. The MD simulations show that the first hydrated shells of both Fe2＋ and Fe3＋ are characterized by a regular octahedron with an Fe-O distance of 2.08 for Fe2＋ and 1.96 for Fe3＋, and rule out the occurrence of a Jahn-Teller distortion in the hydrated shell of an Fe2＋ aqueous solution. The corresponding X-ray absorption near edge fine structure （XANES） calculation successfully reproduces all features in the XANES spectra in Fe2＋ and Fe3＋ aqueous solution. A feature that is located at energy 1 eV higher than the white line （WL） in an Fe3＋ aqueous solution may be assigned to the contribution of the charge transfer.
A penetrating view of the three-dimensional nanostructure of female spermatheca and male flagellum in the species Aleochara verna is obtained with 100-nm resolution using a hard X-ray microscope, which provides a fast noninvasive imaging technology for insect morphology. Through introducing Zernike phase contrast and heavy metal staining, images taken at 8 keV displayed sufficient contrast for observing nanoscale fine structures, such as the spermatheca cochleate duct and the subapex of the flagellum, which have some implications for the study of the sperm transfer process and genital evolution in insects. This work shows that both the spatial resolution and the contrast characteristic of hard X-ray microscopy are quite promising for insect morphology studies and, particularly, provide an attractive alternative to the destructive techniques used for investigating internal soft tissues.
We propose a method for reconstructing a complex field from a series of its near-field diffraction patterns.This method is based on the paraxial Fresnel diffraction equation without making further approximations.Numerical simulations are presented showing that a complex field can even be reconstructed with moderate qualities from its two near-field diffraction patterns and almost exact reconstructions can be obtained when three or more diffraction patterns are used.We also show by numerical simulation that the correct diffraction distances can be recovered in case only coarsely measured values are available.This method may be applied to phase imaging of weak-absorption objects.
