Development of electron differential interferometry and its application to magnetic materials

电子微分干涉技术的发展及其在磁性材料中的应用

• 批准号: 09555021
• 负责人: TANJI Takayoshi
• 金额: $ 7.17万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09555021/
• 关键词: electron holography; differential interferometry; differential microscopy; electron trapezoidal prism; real time phase observation; 電子系台形プリズム

Electron holography, which enables us to measure the electron phase shift with high precise and high resolution, requires a well-defined reference wave. This restricts the application to materials science. The theme of this research is to develop a new electron differential microscopy to overcome this disadvantage of electron holography and a system which makes a real time observation possible.Following results have been obtained in this project :i) In order to compensate for the lack of sensitivity in differential interferometry for weak phase objects, we proposed electron phase differential micrography that is realized by means of digital reconstruction method. For convenience an electron trapezoidal prism has been invented and replaced electron biprism.ii) We successfully observed directly the magnetic vectors in ferromagnetic thin films and that leaking from single magnetic domain particles by the two dimensional differentiation. It has been found that the reference phase reconstructed from all holograms should be coincident to each other, and an effect of Fresnel diffraction at an electron prism is important, too.iii) A complete simulation of electron holograms which include Fresnel effects, the quantum noise and the coherency of electrons has been accomplished.iv) Applying an additional square-wave voltage to the electron trapezoidal prism and recording double-exposure holograms on videotape, we confirmed that the real time observation in electron differential interferometry is available, though the time resolution obtained is about 1 sec. so far.

电子全息术是一种高精度、高分辨率的电子相移测量技术，它需要一个清晰的参考光。这就限制了它在材料科学中的应用。本研究的主题是发展一种新的电子微分显微术，以克服电子全息术的这一缺点，并使真实的时间观测成为可能，在本项目中取得了以下成果：1）为了弥补微分干涉术对弱相位物体灵敏度的不足，我们提出了用数字重建方法实现的电子相位微分显微术。（2）利用二维微分法，我们成功地直接观测到了铁磁薄膜中的磁矢量和单磁畴粒子的磁矢量泄漏。我们发现，从所有全息图中再现的参考相位应彼此一致，电子棱镜的菲涅耳衍射效应也是重要的。iii）对包含菲涅耳效应的电子全息图进行了完整的模拟，iv）在电子梯形棱镜上加一个方波电压，记录双-通过在录像带上曝光全息图，证实了电子差分干涉术中的真实的时间观测是可行的，虽然所获得的时间分辨率约为1秒。迄今

项目成果

T. Hanai: "Characteristics and effectiveness of a foil lens for correction of spherica aberration in scanning transmission electron microscopy"Journal of Electro Microscopy. 47・3. 185-192 (1998)

T. Hanai：“扫描透射电子显微镜中用于校正球面像差的箔透镜的特性和有效性”《电子显微镜杂志》47・3（1998）。

平山司: "電子波干渉による電場・磁場の直視と材料科学への応用"まてりあ. 37・6. 454-460 (1998)

平山司：“通过电子波干涉直接观察电场和磁场及其在材料科学中的应用”Materia 37・6（1998）。

T. Hanai: "Reduction of spherical aberration of a transmission electron microscope by means of a foil lens"Electron Microscopy. 1. 82-84 (1998)

T. Hanai：“通过箔透镜减少透射电子显微镜的球差”电子显微镜。

K. Yamamoto: "Hologram simulation for off-axis electron holography"Ultramicroscopy. in press.

K. Yamamoto：“离轴电子全息术的全息图模拟”超显微镜。

T.Hanai: "Maximum entropy restoration of electron microscope images with random spatial distribution constraint" Scanning Microscopy. supl.11(発表予定). (1998)

T.Hanai：“具有随机空间分布约束的电子显微镜图像的最大熵恢复”扫描显微镜。11（待提交）。