Research on an Improvement of Resolution of Electron Microscope by Means of Maximum Entropy Image Restoration.

1.最大熵（ME）恢复系统的构建：采用高质量扫描仪，在工作站上实现ME恢复程序，取代了以前使用的大型机，构建了一个用于常规透射电子显微镜（CTEM）图像采集和ME恢复的系统.扫描透射电子显微镜（STEM）图像的恢复：一种新开发的ME方法，其被设计为实现推断噪声的随机空间分布（RSD）作为图像熵最大化的约束，被应用于具有低信噪比（SNR）的STEM图像。铁蛋白颗粒的标本被用作一个典型的例子，传统的ME方法未能提供成功的恢复空间扩展的对象。研究发现，通过RSD约束的处理，图像的信噪比得到了提高。该方法也被应用到暗场STEM图像研究的ME恢复对图像模糊的宽电子探针的影响。使用直径相对较大（6.2 nm）的探针，观察到原始直径约7 nm的铁蛋白颗粒，平均直径为12 nm。通过用改进的ME方法处理图像，颗粒尺寸减小到直径为9.8nm，使得原始图像中未分辨的紧密定位的颗粒以高SNR清晰地分辨。CTEM图像的恢复：将改进的ME方法应用于弱相位物体的模型图像。对于大面积的圆盘状物体和点状物体的图像，该方法同时降低了图像的模糊和噪声。在实践中，处理了铁蛋白颗粒的大部分散焦的噪声CTEM图像。改进的ME方法得到了一个成功的恢复图像，减少了模糊和提高信噪比。

1. Construction of Maximum Entropy (ME) Restoration System : A system for acquisition and ME restoration of conventional transmission electron microscope (CTEM) images was constructed by using a high quality scanner and by an implementation of ME restoration programs in a workstation instead of a mainframe used before.2. Restoration of Scanning Transmission Electron Microscope (STEM) Images : A newly developed ME method which was designed to realize a random spatial distribution (RSD) of the inferred noise as a constraint in maximization of the image entropy, was applied to STEM images with low signal-to-noise ratio (SNR). A specimen of ferritin particles was used as a typical example of spatially extended objects for which conventional ME method failed to provide successful restoration. In was found that the SNR of the image was increased by processing with RSD constraint. The method was also applied to dark-field STEM images to study effects of the ME restoration on images blurred by a broad electron probe. With a probe having a relatively large diameter of 6.2 nm, ferritin particles with the original diameter of about 7 nm were observed with an average diameter of 12 nm. By processing the image with the improved ME method, the particle size was reduced to 9.8 nm in diameter so that closely positioned particles, not resolved in the original image, were clearly resolved with a high SNR.3. Restoration of CTEM Images : The improved ME method was applied to a model image of weak phase objects. The blurring and the noise were simultaneously reduced for images of disk objects with a large area as well as point objects. A largely defocused noisy CTEM image of ferritin particles was processed in practice. The improved ME method yielded a successfully restored image with decreased blurring and increased SNR.