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On line digital manipulation process of elastically and inelastically scattered electron signals in scanning transmission electron microscopy

扫描透射电子显微镜中弹性和非弹性散射电子信号的在线数字处理过程

基本信息

批准号：
63850078
负责人：
HIBINO Michio
金额：
$ 5.5万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

1. Improvement of electron detection An electron detector of high sensitivity was investigated for conventional powdered phosphor scintillator of various thicknesses. The scintillator of 0.07mm thickness was found to give the maximum sensitivity at 1OOkV. It was found as well that a YAG single crystal scintillator of lmm thickness gives the sensitivity 4 times as much as the powdered phosphor scintillator. A high-accuracy detection of inelastically scattered and unscattered electroits was realized by installation of a deflection magnet for signal electrons and an aperture diaphragm, to avoid the influence of X ray and stray electrons.2. Digital processing system of image signals A system was developed to record electron signals of up to three kinds with high- accuracy. Special attentions were paid to acquisition error in sampling and the error was reduced within 0.2% by using a Butterworth filter to avoid aliasing.3. Digital manipulation process A proper window of low-pass filter was investigated for improvement of resolution without artifacts by using a method combined by filtering and deconvolution. It was found that the resolution is improved by 40% under the appropriate condition. The quantitative evaluation of normalization process of signal electrons by incident electrons was carried out and it was found that the SN ratio is improved in accordance with the theory. The manipulation among elastically scattered and inelastically scattered electrons revealed that the contrast in proportion to atomic number is obtained in the ratio image and that the contrast of structure of specific element is diminished or enhanced in the difference image by taking an appropriate difference factor.

1.电子检测的改进针对不同厚度的常规粉末荧光粉闪烁体，研究了高灵敏度的电子检测器。 0.07mm 厚度的闪烁体被发现在 100kV 时具有最大灵敏度。还发现1mm厚度的YAG单晶闪烁体的灵敏度是粉状磷光体闪烁体的4倍。通过安装信号电子偏转磁体和孔径光阑，避免了X射线和杂散电子的影响，实现了对非弹性散射和非散射电子的高精度检测。 2．图像信号数字处理系统开发了能够高精度记录多达三种电子信号的系统。采样时特别注意采集误差，采用巴特沃斯滤波器避免混叠，将误差控制在0.2%以内。 3．数字处理过程通过使用滤波和反卷积相结合的方法，研究了低通滤波器的适当窗口，以提高分辨率而没有伪影。结果发现，在适当的条件下，分辨率提高了40%。对入射电子对信号电子的归一化过程进行了定量评估，发现信噪比得到了提高，符合理论。弹性散射和非弹性散射电子之间的操纵表明，在比率图像中获得了与原子序数成比例的对比度，并且通过采用适当的差异因子，在差异图像中特定元素的结构的对比度被减弱或增强。