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

基本信息

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

项目摘要

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.

电子全息术使我们能够高精度、高分辨率地测量电子相移，它需要一个明确的参考波。这限制了其在材料科学中的应用。本研究的主题是开发一种新的电子微分显微镜来克服电子全息术的这一缺点，并开发一种使实时观察成为可能的系统。该项目已获得以下结果：i）为了弥补电子全息术的不足为了提高弱相位物体微分干涉测量的灵敏度，我们提出了通过数字重建方法实现的电子相位微分显微成像。为了方便起见，发明了电子梯形棱镜并取代了电子双棱镜。ii）我们通过二维微分成功地直接观察到了铁磁薄膜中的磁矢量以及从单磁畴粒子泄漏的磁矢量。已经发现，从所有全息图重建的参考相位应该彼此重合，并且电子棱镜处的菲涅尔衍射效应也很重要。iii) 电子全息图的完整模拟，包括菲涅尔效应、量子噪声iv) 对电子梯形棱镜施加额外的方波电压并在录像带上记录双曝光全息图，我们证实了真实的尽管获得的时间分辨率约为1秒，但可以使用电子微分干涉测量法进行时间观察。迄今为止。