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Abstract In grating-based X-ray Talbot interferometry, the wave nature of X-ray radiation is exploited to generate phase contrast images of objects that do not generate sufficient contrast in conventional X-ray imaging relying on X-ray absorption. The phase sensitivity of this interferometric technique is proportional to the interferometer length and inversely proportional to the period of gratings. However, the limited spatial coherency of X-rays limits the maximum interferometer length, and the ability to obtain smaller-period gratings is limited by the manufacturing process. Here, we propose a new optical configuration that employs a combination of a converging parabolic micro-lens array and a diverging micro-lens array, instead of a binary phase grating. Without changing the grating period or the interferometer length, the phase signal is enhanced because the beam deflection by a sample is amplified through the array of converging-diverging micro-lens pairs. We demonstrate that the differential phase signal detected by our proposed set-up is twice that of a Talbot interferometer, using the same binary absorption grating, and with the same overall inter-grating distance.

X-ray Talbot and Talbot–Lau interferometers consisting of transmission gratings are widely used for X-ray phase imaging, which depicts soft materials. This study exploits the use of a pair of concave and convex parabolic gratings instead of a conventional rectangular phase grating to enhance the phase signal optically. To gain insight into the optimal design, signal enhancement is evaluated by directly measuring the self-image formed downstream of the pair. An increase in the differential phase signals is demonstrated as a function of the distance between the pair, and prospects for deploying this concept into a practical phase imaging technique are discussed.

The locomotor system is highly bilateral at the macroscopic level. Homochirality of biological molecules is fully compatible with the bilateral body. However, whether and how single-handed cells contribute to the bilateral locomotor system is obscure. Here, exploiting the small number of cells in the swimming tadpole larva of the ascidian Ciona, we analyzed morphology of the tail at cellular and subcellular scales. Quantitative phase-contrast X-ray tomographic microscopy revealed a high-density midline structure ventral to the notochord in the tail. Muscle cell nuclei on each side of the notochord were roughly bilaterally aligned. However, fluorescence microscopy detected left-right asymmetry of myofibril inclination relative to the longitudinal axis of the tail. Zernike phase-contrast X-ray tomographic microscopy revealed the presence of left-handed helices of myofibrils in muscle cells on both sides. Therefore, the locomotor system of ascidian larvae harbors symmetry-breaking left-handed helical cells, while maintaining bilaterally symmetrical cell alignment. These results suggest that bilateral animals can override cellular homochirality to generate the bilateral locomotor systems at the supracellular scale.

Neutron imaging based on a compact Talbot–Lau interferometer was demonstrated using the RIKEN accelerator-driven compact neutron source (RANS). A compact Talbot–Lau interferometer consisting of gadolinium absorption gratings and a silicon phase grating was constructed and connected to the RANS. Because of pulsed thermal neutrons from the RANS and a position-sensitive detector equipped with time-of-flight (TOF) analysis, moiré interference patterns generated using the interferometer were extracted at a TOF range around the design wavelength (2.37 Å) optimal for the interferometer. Differential phase and scattering images of the metal rod samples were obtained through phase-stepping measurements with the interferometer. This demonstrates the feasibility of neutron phase imaging using a compact neutron facility and the potential for flexible and unique applications for nondestructive evaluation.

An x-ray phase tomographic microscope has been developed by optimizing the optical system for 9-keV synchrotron x rays at BL37XU, SPring-8, Japan. The system consists of a full-field x-ray imaging microscope and a Talbot interferometer. In contrast with our previous system, a Fresnel zone plate for the microscope objective and transmission gratings of the interferometer was designed to improve the refraction sensitivity, with a larger field of view and a higher spatial resolution, utilizing a 28-m space available at BL37XU. An x-ray phase tomographic microscope with a field of view of 375 µm and a spatial resolution of 560 nm was thus constructed, even with a considerably low x-ray dosage. By applying this tomographic microscope to auditory bone specimens of young mice, it was shown that soft tissues in addition to bone tissue could be observed simultaneously without serious radiation damage.

Abstract An X-ray Talbot-Lau interferometer scanning setup consisting of three transmission gratings, a laboratory-based X-ray source that emits X-rays vertically, and an image detector on the top has been developed for the application of X-ray phase imaging to moving objects that cannot be tested clearly with conventional absorption contrast. The grating-based X-ray phase imaging method usually employs a phase-stepping (or fringe-scanning) technique by displacing one of the gratings step-by-step while the object stays still. Since this approach is not compatible with a scanner-type application for moving objects, we have developed a new algorithm for achieving the function of phase-stepping without grating displacement. By analyzing the movie of the moiré pattern as the object moves across the field of view, we obtain the absorption, differential phase, and visibility images. The feasibility of the X-ray phase imaging scanner has been successfully demonstrated for a long sample moving at 5 mm/s. This achievement is a breakthrough for the practical industrial application of X-ray phase imaging for screening objects carried on belt-conveyers such as those in factories.

A two-dimensional array of compound refractive lenses (2D array of CRLs) designed for hard X-ray imaging with a 3.5 mm2 large field of view is presented. The array of CRLs consists of 2D polymer biconcave parabolic 34 × 34 multi-lenses fabricated via deep X-ray lithography. The developed refractive multi-lens array was applied for sub-pixel resolution scanning transmission X–ray microscopy; a raster scan with only 55 × 55 steps provides a 3.5 megapixel image. The optical element was experimentally characterized at the Diamond Light Source at 34 keV. An array of point foci with a 55 µm period and an average size of ca. 2.1 µm × 3.6 µm was achieved. In comparison with the conventional scanning transmission microscopy using one CRL, sub-pixel resolution scanning transmission hard X-ray microscopy enables a large field of view and short scanning time while keeping the high spatial resolution.

Under the JST-ERATO project in progress to develop X-ray and neutron phase-imaging methods together, recent achievements have been selected and reviewed after describing the merit and the principle of the phase imaging method. For X-ray phase imaging, recent developments of four-dimensional phase tomography and phase microscopy at SPring-8, Japan are mainly presented. For neutron phase imaging, an approach in combination with the time-of-flight method developed at J-PARC, Japan is described with the description of new Gd grating fabrication.

Developing long bones alter their shape while maintaining uniform cortical thickness via coordinated activity of bone)forming osteoblasts and bone-resorbing osteoclasts at periosteal and endosteal surfaces, a process we designate trans-pairing. Two types of trans-pairing shift cortical bone in opposite orientations: peri-forming trans-pairing (peri-t-p) increases bone marrow space and endo-forming trans-pairing (endo-t-p) decreases it, via paired activity of bone resorption and formation across the cortex. Here, we focused on endo-t-p in growing bones. Analysis of endo-t-p activity in the cortex of mouse fibulae revealed osteoclasts under the periosteum compressed by muscles, and expression of RANKL in periosteal cells of the cambium layer. Furthermore, mature osteoblasts were localized on the endosteum, while preosteoblasts were at the periosteum and within cortical canals. X-ray tomographic microscopy revealed the presence of cortical canals more closely associated with endo- than with peri-t-p. Sciatic nerve transection followed by muscle atrophy and unloading induced circumferential endo-t-p with concomitant spread of cortical canals. Such canals likely supply the endosteum with preosteoblasts from the periosteum under endo-t-p, allowing bone shape to change in response to mechanical stress or nerve injury. [ABSTRACT FROM AUTHOR]

Since the 1990s, the use of X-ray phase contrast has been extensively studied for imaging weakly absorbing objects consisting of low-Z elements such as biological soft tissues and polymers. The development of X-ray microscopy was also progressing during this time, although absorption contrast was only available. It was straightforward and important to develop phase-contrast X-ray microscopy. One characteristic in the development is that quantitative phase measurement is possible through the acquisition of phase-contrast images under a specific procedure, thanks to digital X-ray image detectors. Therefore, such a technique is called 'phase imaging' rather than phasecontrast imaging in this review. Highly sensitive three-dimensional phase imaging is feasible in combination with tomography. This article reviews the progress in X-ray phase imaging, especially with regards to X-ray microscopy. [ABSTRACT FROM AUTHOR]

Endochondral ossification is a developmental process by which cartilage is replaced by bone. Terminally differentiated hypertrophic chondrocytes are calcified, vascularized, and removed by chondroclasts before bone matrix is laid down by osteoblasts. In mammals, the malleus is one of three auditory ossicles that transmit vibrations of the tympanic membrane to the inner ear. The malleus is formed from a cartilaginous precursor without growth plate involvement, but little is known about how bones of this type undergo endochondral ossification. Here, we demonstrate that in the processus brevis of the malleus, clusters of osteoblasts surrounding the capillary loop produce bone matrix, causing the volume of the capillary lumen to decrease rapidly in post-weaning mice. Synchrotron X-ray tomographic microscopy revealed a concentric, cylindrical arrangement of osteocyte lacunae along capillaries, indicative of pericapillary bone formation. Moreover, we report that overexpression of Fosl1, which encodes a component of the AP-1 transcription factor complex, in osteoblasts significantly blocked malleal capillary narrowing. These data suggest that osteoblast/endothelial cell interactions control growth plate-free endochondral ossification through 'osteogenic capillaries' in a Fosl1-regulated manner. [ABSTRACT FROM AUTHOR]

Abstract  X-ray imaging is a very important technology in the fields of medical, biological, inspection, material science, etc. However, it is not enough to get the clear X-ray imaging with low absorbance. We have produced a diffraction gratings for obtaining high resolution X-ray phase imaging, such as X-ray Talbot interferometer. In this X-ray Talbot interferometer, diffraction gratings were required to have a fine, high accuracy, high aspect ratio structure. Then, we succeeded to fabricate a high aspect ratio diffraction grating with a pitch of 8 μm and small area using a deep X-ray lithography technique. We discuss that the diffraction gratings having a narrow pitch and an large effective area to obtain imaging size of practical use in medical application. If the pitch of diffraction gratings were narrow, it is expected high resolution imaging for X-ray Talbot interferometer. We succeeded and fabricated the diffraction grating with pitch of 5.3 μm, Au height of 28 μm and an effective area of 60 × 60 mm2. [ABSTRACT FROM AUTHOR]

Abstract??Imaging technology using the phase data attracts attention from many researchers as the observation technique of a biomechanical material. We produced a diffraction grating for obtaining high-resolution phase data. We designed the new process flow and developed the fabrication technique composed of MEMS technology, X-ray lithography, and micro electroplating. The X-ray lithography process was performed using the NewSUBARU synchrotron radiation facility. The line and the aspect ratio of this grating were 4??m and above 5??m, respectively. We evaluated the diffraction grating in SPring-8. [ABSTRACT FROM AUTHOR]

When applying phase shifting interferometry to practical phase measurement, the wave may become non-sinusoidal, and could include some phase shift errors. Prior phase shift algorithms are primarily used for sinusoidal cases, and can cause system errors when used for these non-sinusoidal interference. We propose two phase recovery methods for non-sinusoidal interference fringes: specifically, a least-squares-based fitting algorithm that eliminates system errors using a sufficient number of measured images, and a Fourier transform-based method that effectively suppresses system errors using a lower (or insufficient) number of images. Simulation and experimental results verify the efficacy of the proposed methods. [ABSTRACT FROM AUTHOR]

Neutron phase imaging is a developing technology following the earlier development of X-ray phase imaging using gratings. Making high aspect ratio structures for neutron gratings is crucial to ensure the sufficient function of neutron absorption gratings, for which the usage of Gd is effective. Oblique evaporation of Gd on a Si grating is an excellent approach for Gd grating fabrication, but non-uniformity is a remaining problem in fabricating gratings large enough for the required field of view of neutron phase imaging. In this study, we propose a fabrication process, in which a Si grating is moved during the oblique evaporation process to attain uniform deposition of Gd in a 64 mm × 64 mm area. X-ray microtomography was used to evaluate fabricated gratings by depicting deposited Gd density distribution in grating units cut out by a focused ion beam (FIB). [ABSTRACT FROM AUTHOR]

For efficient differential-phase-contrast imaging, we have demonstrated the wavelength-resolved neutron Talbot-Lau interferometry with the wavelength resolution of 0.11 Å over a wide wavelength range of 2.5–7.5 Å at RADEN in the J-PARC Materials and Life Science Experimental Facility. The time-of-flight measurement has clearly showed that the visibility of moiré fringes and intensity oscillations of the interferometer varied continuously with the wavelength, and the wavelength dependence of the differential phase of metal samples was measured. Based on the analysis utilizing this wavelength dependence, we achieved both high statistical precision and high accuracy in the differential-phase-contrast imaging, and succeeded in the quantitative evaluation of the optical potentials of metals. [ABSTRACT FROM AUTHOR]

A high-aspect-ratio absorption grating with a pitch of several µm is a key component of X-ray grating interferometery, which is an X-ray phase imaging technique that allows for highly sensitive X-ray imaging with a compact laboratory X-ray source. Here, we report that X-ray phase imaging was successfully performed at 15 keV by using a 23 ± 1-µm-height, 9-µm-pitch absorption grating (10 × 10 mm2) based on Gd (Gd60Cu25Al15) fabricated by a metallic glass imprinting technique. The imprinting technique is cost-efficient and has a high-production rate, and will be widely used for fabricating gratings not only for X-rays but also neutrons in the near future. [ABSTRACT FROM AUTHOR]

X-ray Talbot–Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a conventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus bearing tremendous potential for future clinical diagnosis. In this work, by changing the accelerating voltage of the x-ray tube from 35 kV to 45 kV, x-ray phase-contrast imaging of a test sample is performed at each integer value of the accelerating voltage to investigate the characteristic of an x-ray Talbot–Lau interferometer (located in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan) versus tube voltage. Experimental results and data analysis show that within a range this x-ray Talbot–Lau interferometer is not sensitive to the accelerating voltage of the tube with a constant fringe visibility of ∼ 44%. This x-ray Talbot–Lau interferometer research demonstrates the feasibility of a new dual energy phase-contrast x-ray imaging strategy and the possibility to collect a refraction spectrum. [ABSTRACT FROM AUTHOR]

X-ray grating interferometry has been spotlighted in the last decade as a technique for X-ray phase imaging and tomography. In this paper, we report that this interferometry can also be applied to the real-space mapping of weak diffuse scattering (ultrasmall-angle X-ray scattering) in grazing incidence geometry. A preliminary experiment using a laboratory X-ray source demonstrated that image contrast is successfully generated by the diffuse scattering from a micrometer-sized structure fabricated on a silicon wafer. This technique works with a large beam with a wide angular spread from a low-brilliance X-ray source, and has potential to become a powerful tool for mapping structures in real space from which ultrasmall-angle X-ray scattering arises. [ABSTRACT FROM AUTHOR]