Daisuke Yamakawa

Bio: Daisuke Yamakawa is an academic researcher from Osaka University. The author has contributed to research in topics: Wavefront & Adaptive optics. The author has an hindex of 6, co-authored 7 publications receiving 583 citations.

Breaking the 10 nm barrier in hard-X-ray focusing

Abstract: X-ray sources such as free-electron lasers offer the potential to study matter at unprecedented spatial and temporal resolution. But that potential is limited by the poor quality of conventional X-ray optical elements. An in situ technique that corrects for wavefront aberrations and allows X-rays to be focused to a spot just 7 nm wide could provide a solution.

Focusing mirror for x-ray free-electron lasers.

Abstract: We present the design, fabrication, and evaluation of a large total-reflection mirror for focusing x-ray free-electron laser beams to nanometer dimensions. We used an elliptical focusing mirror made of silicon that was 400 mm long and had a focal length of 550 mm. Electrolytic in-process dressing grinding was used for initial-step figuring and elastic emission machining was employed for final figuring and surface smoothing. A figure accuracy with a peak-to-valley height of 2 nm was achieved across the entire area. Characterization of the focused beam was performed at BL29XUL of SPring-8. The focused beam size was 75 nm at 15 keV, which is almost equal to the theoretical size.

A stitching figure profiler of large X-ray mirrors using RADSI for subaperture data acquisition

Abstract: In the third- and coming fourth-generation synchrotron radiation facilities, X-rays having both high brightness and high coherency can be utilized. Such X-rays require high accuracy in the reflective optics. In this study, we developed an ultra-precise measurement instrumentation for tangentially long X-ray mirrors using a Fizeau interferometer. In the system, the mirror figure is measured by stitching the subaperture profiles measured by the relative-angle determinable stitching interferometry, which we developed previously. High measurement accuracy of approximately 2 nm (peak to valley) was achieved in the measurement of a 400 mm-long aspherical surface.

Wavefront Control System for Phase Compensation in Hard X-ray Optics

Abstract: A highly precise adaptive optical system that can be used in the hard X-ray region was developed. To achieve highly precise control of the wavefront shape, we discussed an optical system with a bendable mirror of deformation accuracy better than 0.4 nm RMS. Using the system, we demonstrated the controllability of the wavefront of a 15 nm hard X-ray nanobeam. The intensity profile of the wavefront-modified beam was in good agreement with the wave-optically calculated profile.

Development of adaptive mirror for wavefront correction of hard x-ray nanobeam

Abstract: We present the development of a phase compensator for wavefront control of X-rays. The optical device is a 150 mm-long total reflection mirror, the shape of which can be curved by adjusting the bias voltages of 36 piezoelectric ceramic plates attached to the mirror. The mirror surface was smoothed and made flat by elastic emission machining. To achieve a high degree of the accuracy in the controllability of a curved line, a Fizeau interferometer is placed in front of the mirror surface to monitor its shape in the experiment. We will apply this device to the optical system for the realization of sub-10-nm hard X-ray focusing.

Extremely high-intensity laser interactions with fundamental quantum systems

Abstract: The field of laser-matter interaction traditionally deals with the response of atoms, molecules, and plasmas to an external light wave. However, the recent sustained technological progress is opening up the possibility of employing intense laser radiation to trigger or substantially influence physical processes beyond atomic-physics energy scales. Available optical laser intensities exceeding ${10}^{22}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$ can push the fundamental light-electron interaction to the extreme limit where radiation-reaction effects dominate the electron dynamics, can shed light on the structure of the quantum vacuum, and can trigger the creation of particles such as electrons, muons, and pions and their corresponding antiparticles. Also, novel sources of intense coherent high-energy photons and laser-based particle colliders can pave the way to nuclear quantum optics and may even allow for the potential discovery of new particles beyond the standard model. These are the main topics of this article, which is devoted to a review of recent investigations on high-energy processes within the realm of relativistic quantum dynamics, quantum electrodynamics, and nuclear and particle physics, occurring in extremely intense laser fields.

X-Rays and Extreme Ultraviolet Radiation: Principles and Applications

Abstract: This self-contained, comprehensive book describes the fundamental properties of soft x-rays and extreme ultraviolet (EUV) radiation and discusses their applications in a wide variety of fields, including EUV lithography for semiconductor chip manufacture and soft x-ray biomicroscopy. The author begins by presenting the relevant basic principles such as radiation and scattering, wave propagation, diffraction, and coherence. He then goes on to examine a broad range of phenomena and applications. The topics covered include EUV lithography, biomicroscopy, spectromicroscopy, EUV astronomy, synchrotron radiation, and soft x-ray lasers. He also provides a great deal of useful reference material such as electron binding energies, characteristic emission lines and photo-absorption cross-sections. The book will be of great interest to graduate students and researchers in engineering, physics, chemistry, and the life sciences. It will also appeal to practicing engineers involved in semiconductor fabrication and materials science.

Nanoscale X-ray imaging

Abstract: Recent years have seen significant progress in the field of soft- and hard-X-ray microscopy, both technically, through developments in source, optics and imaging methodologies, and also scientifically, through a wide range of applications While an ever-growing community is pursuing the extensive applications of today's available X-ray tools, other groups are investigating improvements in techniques, including new optics, higher spatial resolutions, brighter compact sources and shorter-duration X-ray pulses This Review covers recent work in the development of direct image-forming X-ray microscopy techniques and the relevant applications, including three-dimensional biological tomography, dynamical processes in magnetic nanostructures, chemical speciation studies, industrial applications related to solar cells and batteries, and studies of archaeological materials and historical works of art

Breaking the 10 nm barrier in hard-X-ray focusing

Abstract: X-ray sources such as free-electron lasers offer the potential to study matter at unprecedented spatial and temporal resolution. But that potential is limited by the poor quality of conventional X-ray optical elements. An in situ technique that corrects for wavefront aberrations and allows X-rays to be focused to a spot just 7 nm wide could provide a solution.

Scintillating Nanoparticles as Energy Mediators for Enhanced Photodynamic Therapy

Abstract: Achieving effective treatment of deep-seated tumors is a major challenge for traditional photodynamic therapy (PDT) due to difficulties in delivering light into the subsurface. Thanks to their great tissue penetration, X-rays hold the potential to become an ideal excitation source for activating photosensitizers (PS) that accumulate in deep tumor tissue. Recently, a wide variety of nanoparticles have been developed for this purpose. The nanoparticles are designed as carriers for loading various kinds of PSs and can facilitate the activation process by transferring energy harvested from X-ray irradiation to the loaded PS. In this review, we focus on recent developments of nanoscintillators with high energy transfer efficiency, their rational designs, as well as potential applications in next-generation PDT. Treatment of deep-seated tumors by using radioisotopes as an internal light source will also be discussed.