First Talbot interferometry in the hard X-ray region was demonstrated using a pair of transmission gratings made by forming gold stripes on glass plates. By aligning the gratings on the optical axis of X-rays with a separation that caused the Talbot effect by the first grating, moiré fringes were produced inclining one grating slightly against the other around the optical axis. A phase object placed in front of the first grating was detected by moiré-fringe bending. Using the technique of phase-shifting interferometry, the differential phase corresponding to the phase object could also be measured. This result suggests that X-ray Talbot interferometry is a novel and simple method for phase-sensitive X-ray radiography.
Microtomography using synchrotron radiation has become a valuable tool for the 3-d investigation of samples in the fields of e.g.Medicine, biology and material science.At HASYLAB at DESY absorption-contrast microtomography is applied in user mode at three different beamlines BW2, W2 and BW5 covering the energy range from 4 keV to 150 keV.Furthermore intererometric phase-contrast microtomography was developed and applied using 12, 20, 24 and 70 keV.Furthermore different scanning techniques were developed and applied to larger samples up to 24 mm in diameter and 40 mm in height.The experimental setup originally developed at the University of Dortmund, Germany and the improvements made at Hasylab to provide for a user experiment for absorption-contrast microtomography will be described.Several examples will demonstrate the practical application of the current system as a user experiment for performing continuous tomographical scans.
Since the synchrotron X‐rays are intense enough even after the sequential expansion of the X‐ray beam by successive asymmetric Bragg reflections, live refraction images of internal structure for biological materials can be seen on an X‐ray image sensor. Video images of some living insects or a frog or a mouse show clearly their internal structures of the body, for instance, cellular structures in a lung.
Results of phase-contrast X-ray imaging are presented. The optical system employed consisted of a successive arrangement of horizontal and vertical (+, -) double crystals taking asymmetric Bragg reflection with an asymmetry factor of ∼0.2. The original beam size was thus expanded in both directions and the field of view actually obtained was ∼5×5 mm 2 . Boundary structures in samples were clearly observed with much higher contrast than those obtained in conventional absorption-contrast imaging. Since this method works in real time, it will provide a new X-ray imaging diagnosis technique for in situ observation over a large area of the samples.
The diamond crystals with a (100) or a (111) surface are characterized by the uses of rocking curve measurements, reciprocal lattice mapping and Lang topography method. The full widths at the half maxima of the rocking curves at the X-ray energy of 8.04 keV have been measured to be 6.5 arcsec and 6.3 arcsec for 400 and 111 Bragg reflection, respectively. While the value for 400 reflection is 1.3 times larger than the theoretical value, that for 111 reflection is almost the same as the theoretical one. A sub-peak of about 15 arcsec leaning to the main peak is clearly seen in the reciprocal lattice maps of (100) crystals. No sub-peak can be seen in those of (111) crystal. In addition, some streaky intensity distribution due to a dynamical effect of the X-ray diffraction, being elongated in the radial direction from the reflection point, is clearly seen. This means that crystallinity of (111) planes is more perfect. From the (100) Lang's topographs, it has also been clarified that the diamond crystals include some defect bundles inside the crystals.
An imaging transmission hard X-ray microscope has been constructed at the Hyogo-BL (BL24XU) of SPring-8. It makes use of X-ray phase zone plates (PZP's) made of tantalum as its condenser and objective lenses. The objective PZP has an outermost zone width of 250 nm, which corresponds to the theoretically expected spatial resolution of 300 nm. An experiment was performed at the photon energy of 10 keV to check the performance of the microscope. Since a 250 nm line-and-space pattern was clearly resolved, we concluded that the microscope attained a spatial resolution limit better than 500 nm. A few samples were also examined and the feasibility of the microscope was successfully demonstrated.
