Publications by authors named "Hiroto Motoyama"
Damage thresholds and structures on a metal aluminum and an aluminum oxide crystal induced by the soft x-ray free electron laser irradiations were evaluated. Distinctive differences in damage thresholds and structures were observed for these materials. On the aluminum oxide crystal surface, in particular, a novel, to the best of our knowledge, surface processing, which we suggest defining as "peeling," was recognized.
View Article and Find Full Text PDFIn this study, figure correction of a master mandrel of a Wolter mirror by organic abrasive machining (OAM) was demonstrated. In OAM, a flow of slurry, dispersed with organic particles, locally removes the surface of a workpiece in contact with a rotating machining tool. A computer-controlled machining system was used to perform the selective removal of a fused silica surface at a spatial resolution of 200 µm.
View Article and Find Full Text PDFWe developed a copper electroforming replication (CER) process to fabricate precise ellipsoidal mirrors for soft x-ray focusing. Some applications of ellipsoidal mirrors in x-ray microscopy require that all components that are close to samples, including the mirrors, are made of non-magnetic materials. In this study, a non-magnetic copper ellipsoidal mirror was fabricated by replicating a figured and super-polished quartz glass mandrel using an electroforming technique.
View Article and Find Full Text PDFWe demonstrate sub-micrometer processing of two kinds of thin films, polymethyl methacrylate (PMMA) and metal nano-particle resist, by focusing high-order harmonics of near-IR femtosecond laser pulses in the extreme ultraviolet (XUV) wavelength region (27.2-34.3 nm) on the thin film samples using an ellipsoidal focusing mirror.
View Article and Find Full Text PDFWe developed a full-field microscope with twin Wolter mirrors for soft X-ray free-electron lasers. The Wolter mirrors for a condenser and an objective were fabricated using an electroforming process with a precisely figured master mandrel. In the imaging system constructed at SACLA BL1, sub-micrometer spatial resolution was achieved at wavelengths of 10.
View Article and Find Full Text PDFIntense sub-micrometre focusing of a soft X-ray free-electron laser (FEL) was achieved by using an ellipsoidal mirror with a high numerical aperture. A hybrid focusing system in combination with a Kirkpatrick-Baez mirror was applied for compensation of a small spatial acceptance of the ellipsoidal mirror. With this system, the soft X-ray FEL pulses were focused down to 480 nm × 680 nm with an extremely high intensity of 8.
View Article and Find Full Text PDFArticle Synopsis
- Probing spatial coherence of X-rays is crucial for designing advanced optical systems in synchrotron radiation and free-electron lasers.
- Traditional double-slit experiments face limitations in measuring spatial coherence over large distances due to narrow interference fringe spacing.
- A new Fresnel-mirror-based optical system was developed to control interference patterns at the SPring-8 facility, allowing for quantitative measurement of coherence related to virtual source size for optimization of beamline optical systems.
Article Synopsis
- An x-ray ellipsoidal mirror is crucial for focusing soft x-rays, but creating one with the required nanometer-level accuracy is challenging, especially for small diameters.* -
- Researchers developed a method to fabricate these mirrors using nickel sulfamate electroforming on a high-precision quartz mandrel that has the mirror's inverted shape.* -
- A mirror measuring 40-mm in length was created, showing a replication error of 27.2 nm overall and 14.7 nm in the central area, enabling the potential to focus soft x-rays down to a 400 nm diameter spot.*
Fabrication of a precise ellipsoidal mirror for soft X-ray nanofocusing.
Rev Sci Instrum
September 2018
Article Synopsis
- Grazing incidence mirrors for X-rays are beneficial because they eliminate chromatic aberration and can focus efficiently.
- While there are existing nanofocusing mirrors for hard X-rays, soft X-ray mirrors with similar capabilities are lacking, particularly for focusing below 100 nm at energies under 1 keV.
- This study presents a new fabrication process for ellipsoidal mirrors, which achieved a focus size of under 250 nm at 300 eV, showing potential for advanced X-ray mirror designs, including Wolter mirrors.