Talbot-Lau x-ray phase-contrast setup for fast scanning of large samples

Abstract Compared to conventional attenuation x-ray radiographic imaging, the x-ray Talbot-Lau technique provides further information about the scattering and the refractive properties of the object in the beam path. Hence, this additional information should improve the diagnostic process concerning medical applications and non-destructive testing. Nevertheless, until now, due to grating fabrication process, Talbot-Lau imaging suffers from small grating sizes (70 mm diameter). This leads to long acquisition times for imaging large objects. Stitching the gratings is one solution. Another one consists of scanning Talbot-Lau setups. In this publication, we present a compact and very fast scanning setup which enables imaging of large samples. With this setup a maximal scanning velocity of 71.7 mm/s is possible. A resolution of 4.1 lines/mm can be achieved. No complex alignment procedures are necessary while the field of view comprises 17.5 × 150 cm2. An improved reconstruction algorithm concerning the scanning approach, which increases robustness with respect to mechanical instabilities, has been developed and is presented. The resolution of the setup in dependence of the scanning velocity is evaluated. The setup imaging qualities are demonstrated using a human knee ex-vivo as an example for a high absorbing human sample

Application of Grating-Based Interferometry to Additive Manufacturing, Lithium-ion Batteries, and Crystals

X-ray and neutron imaging are convenient ways to non-destructively observe novel materials. X-rays provide advantages of low cost and high brilliance while neutrons show bulk and isotopic sensitivity. Imaging provides a way for observing chemical and physical properties of materials without the need for destruction. The way of the imaging future is utilizing imaging with grating-based interferometry. In comparison to traditional radiography and tomography, by using absorption and phase gratings in the beam path, the absorption, phase, and scattering of a sample can be detected. In essence, three image datasets can be obtained in one experiment, saving substantially on costs (especially at expensive neutron facilities), time and materials. With several methods of interferometry available, the focus in this work is Talbot-Lau interferometry and newer designs referred to as near-field and far-field interferometry. X-ray Talbot-Lau interferometry experiments were performed at the LSU synchrotron, Center for Advanced Microstructures and Devices (CAMD), using a microfocus X-ray tube and synchrotron X-rays (38 keV). Neutron Talbot-Lau experiments were performed at the CONRAD2 beamline (HZB, Berlin, Germany) and far-field experiments at the NG6 beamline (NIST, Gaithersburg, USA). Neutron imaging of the additive manufactured samples revealed pore structures and evi- dence of fracture as a function of fatigue. Battery imaging shows the migration of lithium across battery layers on a visual and quantitative level. X-ray and neutron imaging of potentially twinned crystals revealed the importance of preserving data in the 2D projection images that was lost in volume reconstruction. A comparison of Talbot-Lau, near-field, and far-field interferometry with application to additively manufactured samples, lithium-ion batteries, and geometrically twinned crystals is presented

Structured Beams as Quantum Probes

This thesis describes several projects under the common theme of generating and manipulating the spatial quantum phase structure of matter and electromagnetic waves. Experiments dealing with the following topics are addressed: perfect crystal neutron interferometry, far-field phase-grating moire interferometry, orbital angular momentum (OAM), spin-orbit states, and lattices of spin-orbit states. The first focus of the thesis is describing the work related to the construction of a new beamline dedicated to quantum information related neutron interferometry experiments at the National Institute of Standards and Technology's Center for Neutron Research. This includes the development of the necessary environmental isolation, phase stability, and temperature isolation mechanisms; and the installation and optimization of spin polarization elements. The new beamline is now operational and it is currently one of only three neutron interferometry facilities in the world. The second focus of the thesis is to describe the development and characterization of far-field phase-grating moire neutron interferometry. This technique enables studies that are complimentary to those of perfect crystal neutron interferometry experiments. It may be used to probe structured materials and characterize neutron interactions with potential gradients. A two phase-grating moire neutron interferometer was developed, characterized, and optimized. This setup was then employed to probe the microstructure of a monodisperse suspension of 2 um diameter polystyrene spheres. Furthermore, a three phase-grating moire neutron interferometer was developed and characterized. This unique setup promises a wide range of impactful experiments from far-field imaging of material substructure to fundamental physics. The third focus of the thesis is to describe neutron OAM. These experiments revolve around the preparation and characterization of an azimuthally varying phase profile. The demonstration of neutron OAM using a perfect crystal neutron interferometer is described, where a spiral phase plate was used to induce OAM in one of the paths of the interferometer. Furthermore, a modified setup was used to perform neutron holography of a macroscopic object which induces an azimuthally varying phase profile. These methods provide a new tool for interferometric testing of neutron optics and the characterization of coherence of neutron beams. The last focus of the thesis is to describe matter wave and optical spin correlated OAM (spin-orbit) states. Methods to prepare neutron spin-orbit states via special geometries of magnetic fields are proposed. The preparation, entanglement characterization, and proposed experimental verification of such states are described in detail. Furthermore, a method which is capable of preparing lattices of optical and neutron spin-orbit states is introduced and described. This method utilizes novel optical and neutron devices and it is based on coherent averaging and spatial control methods borrowed from nuclear magnetic resonance. The experimental preparation and characterization of optical lattices of spin-orbit states is described in detail

Energy: A continuing bibliography with indexes

This bibliography lists 1920 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System from July 1, 1980 through September 30, 1980