Updated on 2025/01/07

写真a

 
Ryuji Nishi
 

Degree

  • Doctor (Engineering)   Thesis ( 1997.3   Osaka University )

Research Interests

  • Electron Optics

Research Areas

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Measurement engineering  / Electron Optics

Education

  • Osaka University   Department of Electronic Engineering   Graduated

    1986.4 - 1990.3

  • Osaka University   Department of Electronic Engineering   Master's Course   Completed

    1990.4 - 1992.3

Research History

  • Osaka University   Research Assistant

    1992.4 - 1998.3

  • Osaka University   Research Assistant

    1998.4 - 2003.3

  • Osaka University   Research Assistant

    2003.4 - 2004.10

  • Osaka University

    2004.11 - 2007.3

  • Osaka University   Associate Professor

    2007.4 - 2020.3

  • Fukui University of Technology   Professor

    2020.4 - 2023.3

  • Osaka University

    2020.4

  • Fukui University of Technology   Professor

    2023.4

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Qualification acquired

  • Land Radio Engineer (1-2 class)

  • Chief Person of Radiation Handling (first and second kind)

  • Hygiene Engineering Hygiene Manager

  • X-ray Work Chief Person

  • Gamma Ray Penetration Photography Work Chief Person

 

Papers

  • Low-Aberration ExB Deflector Optics for Scanning Electron Microscopy Reviewed

    Momoyo Enyama, Jun Yamasaki, Ryuji Nishi, Hiroyuki Ito

    Microscopy   72 ( 5 )   399 - 407   2023.10

     More details

    To suppress aberrations in the signal electron optics of a scanning electron microscope, we propose ExB deflector (deflector with superimposed electric and magnetic fields) optics that cancel the aberrations generated during large-angle deflection. This improves the resolution of the angle or position of the signal electrons on the sample surface, allowing them to be discriminately detected. The proposed optics consist of two ExB deflectors and a transfer system with two 4-f systems, or systems that have four times the focal length, placed between them. This configuration maintains the symmetry of the electron beam trajectory throughout the transfer system such that aberrations generated by the first ExB deflector are negated by the second. The effect of the proposed optics was confirmed using a ray-tracing simulation of the electron beam, and the aberration was reduced to at most one-tenth of that in the case with only one ExB deflector. Furthermore, as an example, we examined the implementation of the proposed ExB deflector optics to resolve the signal electron angle and found that the sample emission angle range of 80° can be resolved with an angular resolution of 1°. Therefore, the proposed ExB deflector optics can be applied to the signal electron optics of a scanning electron microscope to improve the resolution of the signal electrons.

  • Application of ultra-high voltage electron microscope tomography to 3D imaging of microtubules in neurites of cultured PC12 cells Reviewed

    T. Nishida, R. Yoshimura, R. Nishi, Y. Imoto, Y. Endo

    Journal of Microscopy   278 ( 1 )   42 - 48   2020.4

     More details

    Electron tomography methods using the conventional transmission electron microscope have been widely used to investigate the three-dimensional distribution patterns of various cellular structures including microtubules in neurites. Because the penetrating power of electrons depends on the section thickness and accelerating voltage, conventional TEM, having acceleration voltages up to 200 kV, is limited to sample thicknesses of 0.2 μm or less. In this paper, we show that the ultra-high voltage electron microscope (UHVEM), employing acceleration voltages of higher than 1000 kV (1 MV), allowed distinct reconstruction of the three-dimensional array of microtubules in a 0.7-μm-thick neurite section. The detailed structure of microtubules was more clearly reconstructed from a 0.7-μm-thick section at an accelerating voltage of 1 MV compared with a 1.0 μm section at 2 MV. Furthermore, the entire distribution of each microtubule in a neurite could be reconstructed from serial-section UHVEM tomography. Application of optimized UHVEM tomography will provide new insights, bridging the gap between the structure and function of widely-distributed cellular organelles such as microtubules for neurite outgrowth.

    Key words: microtubule, neurite, section thickness, electron tomography, ultra-high voltage electron microscope

  • Study on higher performance of imaging and observation system in ultrahigh voltage electron microscopy

    Ryuji Nishi

    1997.3

     More details

    This paper summarizes the research findings on improving the performance of imaging lenses and observation systems to make ultra-high voltage electron microscope suitable for in-situ observation. The study is structured into seven chapters, and the following is an outline of each chapter:
    Chapter 1 introduces the features of ultra-high voltage electron microscopes, the performance requirements for in-situ observation, and the associated challenges. It also outlines the objectives of this study and the structure of the paper.
    Chapter 2 proposes a new magnetic circuit model that separates the causes of the objective lens's response delay into three factors: the coil, cooling plate, and magnetic circuit. Analytical evaluations of the magnetic flux density at the center of the lens gap were conducted. It was shown that cutting off the eddy currents flowing through the cooling plate significantly improves the response speed. This improvement was quantitatively verified through dynamic analysis of the magnetic flux density using the finite element method.
    Chapter 3 describes how processing the lens cooling plate to eliminate eddy currents significantly improved the rise characteristics of the lens. The frequency and time response characteristics of the magnetic flux density at the center of the lens were measured and validated. Additionally, a focusing lens with a small magnetic circuit independent of the objective lens magnetic circuit was introduced to compensate for delay components caused by the penetration of magnetic flux into the deeper magnetic circuit.
    Chapter 4 presents a new imaging mode that eliminates the mechanical movement of the aperture, enabling rapid switching between enlarged and diffraction images using only lens excitation switching. The electron optical parameters of this imaging mode when applied to an ultra-high voltage electron microscope were calculated, and its feasibility was confirmed.
    Chapter 5 investigates the optimal conditions for fluorescent screens with high resolution and high luminous efficiency for ultra-high voltage electron microscopes. Two types of screens—optically transparent single-crystal screens and opaque powder screens—were studied. The emission spread characteristics were quantified for each thickness and depth. Cross-sectional observations of the fluorescent screens were conducted to quantitatively determine the emission spread distribution, and spread functions were derived. Based on these measurements, the emission spread mechanism of fluorescent screens was clarified, and optimal conditions for fluorescent screens for ultra-high voltage electron microscopes were established.
    Chapter 6 quantitatively evaluates the resolution of a newly adopted high-sensitivity, high-resolution HARPICON camera. The resolution of the TV observation system, consisting of the fluorescent screen and TV camera, was determined, and key points for improving resolution were identified.
    Chapter 7 concludes the paper by summarizing the findings and discussing future challenges.

Presentations

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Teaching Experience

  • Electronic Circuit II

    2024.10
    Institution:Fukui University of Technology

  • Digital Signal Processing

    2021.10
    Institution:Fukui University of Technology

  • Electron Beam Nano Imaging

    2016.10
    Institution:Osaka University

 

Academic Activities