Contrast-to-gradient method for the evaluation of image resolution taking account of random noise in scanning electron microscopy

We have taken random image noise into consideration in the contrast-to-gradient (CG) method for the evaluation of image resolution R in scanning electron microscopy (SEM). When looking at the local fine pattern in the SEM micrograph containing much random noise, viewers gradually expand the region of interest (ROI) to improve the signal-to-noise ratio (SNR) and to recognize the pattern. We employed this approach in the CG algorithm to evaluate potential resolution Rpot, which is defined as the minimal/most accurate CG resolution calculated in the ROI expanding process. The image noise or SNR also is evaluated by the parameter deltaR / R, where deltaR is a standard deviation of R. The Rpot values depending on SNR are useful for comparison among images containing different random noise.     

Influence of random noise on the contrast-to-gradient image resolution in scanning electron microscopy

The contrast-to-gradient (CG) method has been proposed previously for the evaluation of image resolution in scanning electron microscopy (SEM). The CG resolution is based on the local resolution, which is defined as the distance to recognize the object's local surface at each pixel position. Then, the CG resolution R is inherently influenced by random noise contained in the image. The present study demonstrates the influence of random noise on the R-values using both personal computer-made dot patterns in various sizes and densities and SEM test micrographs. It is found that the R-values increase with increasing random noise intensity N and their increases are smaller for higher-density patterns, but the R-values are independent of their image sizes under constant pattern density. In addition, the standard CG algorithm is modified especially for straightly fabricated patterns along the x- (or y-) axis, resulting in an improvement in the measurement accuracy of y- (or x-) directional resolutions. The straightness as known information is utilized fully to recognize the local pattern in the random noise.     

Evaluation of both image resolution and contrast-to-noise ratio in scanning electron microscopy

The contrast-to-gradient (CG) resolution has been defined as a weighted harmonic mean of the local resolution, i.e. the length defining the object's local fine structure at each pixel position. The newly defined resolution Res is defined as 2 sigma/ sqrt 2, where 2 sigma is a sharpness factor of the image pattern obtained by the conversion 2 sigma = ARCG + B using default constants A and B. In the present study, we have extended the algorithm to change the constants from default values to calibrated ones using standard images that are same in both pattern and contrast-to-noise ratio (CNR) as the original SEM image to be evaluated. The calibrated image resolution with a weak noise dependency is evaluated with the CNR as a given parameter.     

放线菌扫描电镜样品制备方法比较研究

目的:比较和筛选放线菌扫描电镜样品制备方法。方法:通过培养获得插片、菌饼和发酵液3种待处理样品,根据单因素试验设计原则采用双固定、单固定、磷酸缓冲液清洗、生理盐水清洗、蒸馏水清洗、丙酮脱水、乙醇脱水和直接表面镀金等8种方法对样品进行处理。结果:取样时间直接影响观察样品形态的丰富度;插片样品扫描获得的结果较为理想;不同的固定、清洗和脱水等处理过程也对样品的细节产生了影响。结论:插片样品直接干燥喷金扫描观察是一种简便、快速的方法,对于常规的放线菌观察与鉴定较为实用,也为其它微生物扫描电镜观察提供了参考。     

模拟扫描电镜像衬度的体构件Monte Carlo方法

利用Mollte Carlo计算方法可以模拟电子束与样品的相互作用过程,从而了解扫描电子显微学中信号的产生机制,本工作中,我们采用体构件法来产生复杂试样的几何构型,利用光线追踪算法求得散射事件间的步长抽样修正。电子散射的物理模型则采用Mott散射截面描述电子与原子间的弹性相互作用,以及用介电函数理论描述电子与固体的非弹性相互作用,同时还考虑到了二次电子的级联产生过程．以此,我们模拟计算出了若干复杂几何体的二次电子像和背散射电子像。     

一种提高扫描电子显微镜－能谱空间分辨率的方法

目前,扫描电子显微镜－能谱（ SEM?EDS）联用技术在分析测试领域已得到广泛应用,它可对材料和生物样品的微观表面进行形貌观察,并对样品中所选定的微区内进行元素成分定性定量以及元素分布分析。但是,由于元素的特征X射线能量高,在样品中的出射范围较深,能谱的空间分辨率较差,导致在使用传统制样方法时都不可避免地会受到来自叠加样品特征X射线以及基底材料特征X射线的干扰,从而影响最终实验结果。为了克服能谱空间分辨率不足的问题,本文应用薄片法的原理研制了一种新的装置,将纳米厚度的样品分散在装置的碳膜上,进行能谱分析。通过与传统实验的对比,附加新装置后其能谱空间分辨率较以往常规实验提高了2～4倍。     

Influence of a combination of random noise and pattern-edge width (in pixels) on contrast-to-gradient image resolution in scanning electron microscopy

The contrast-to-gradient (CG) method has been proposed previously for the evaluation of image resolution in scanning electron microscopy (SEM). In the CG algorithm, the image to be evaluated is gradually reduced to form the 1/r-reduced image (r = 1, 2, 3, ...) until the representative features of local patterns are accurately recognizable after the corresponding r-th noise reduction. We have studied the influence of a combination of random noise and pattern-edge width (in pixels) on the CG resolution R using both PC-made test images and typical SEM images. As the random noise is larger, the value of R becomes larger (or poorer). The increase in R due to the noise influence is more significant for the narrower width of the pattern edge. This satisfactorily agrees with the common idea that the image resolution is to reflect the sharpness of the pattern edge recognized in the image noise. By revising the form of DeltaR from the weighted standard fluctuation of R to the differential of R, a significantly weak N(dot)-dependency on R has been favorably confirmed, with keeping firmly the noise-dependency on R. Here, N(dot) is the number of pattern dots in the image.     

分子取向的高分辨率扫描隧道显微术

本文介绍了一种借助于扫描隧道显微镜的空间高分辨能力探测单个分子取向的方法.利用这种方法,我们研究了以下四种体系中的分子取向二维C 60分子阵列;C 60(111)多层膜表面;吸附在Si(111) (7×7)表面的C 60单分子;Au(111)表面的硫醇自组装单分子层膜.结合局域密度近似方法理论计算,我们确定了以上体系中的分子取向.     

An EDTA-KOH method to expose bone cells for scanning electron microscopy.

To observe bone cells by scanning electron microscopy (SEM), the mouse parietal bones were processed by decalcification with EDTA and digestion of collagen fibers with KOH to remove the bone matrix, in addition to the conventional preparation for SEM. The critical-point-dried specimens were split into two membranous pieces along the gaps formed by removing the bone matrix. By this method, osteoclasts showing full three-dimensional images of ruffled borders, osteoblasts showing special structures on the surfaces facing the bone matrix, and osteocytes extending many slender processes were clearly demonstrated in SEM. This new method may provide new viewpoints in bone cell biology.     

Scanning electron mirror microscopy and scanning electron microscopy of integrated circuits

The recently developed scanning electron mirror microscope (SEMM) is compared with other types of electron microscopes, such as the electron mirror microscope (EMM) and the scanning electron microscope (SEM), for examining integrated circuits. Potential advantages of the SEMM include high resolution, elimination of electron bombardment damage, and high sensitivity of voltage gradients, magnetic fields, and topography. Preliminary observations of integrated, circuits obtained with the feasibility SEMM at various specimen potentials are discussed.     

扫描电镜血管内皮细胞硝酸银染色方法的改良

介绍一种简单适用的血管内皮细胞硝酸银染色方法,可使扫描电镜下内皮细胞的表面结构和反应血管通透性的形态改变得到良好展现。     

Progress in aberration-corrected scanning transmission electron microscopy

A new corrector of spherical aberration (C(S)) for a dedicated scanning transmission electron microscope (STEM) is described and its results are presented. The corrector uses strong octupoles and increases C(C) by only 0.2 mm relative to the uncorrected microscope. Its overall stability is greatly improved compared to our previous design. It has achieved a point-to-point resolution of 1.23 A in high-angle annular dark field images at 100 kV. It has also increased the current available in a 1.3 A-sized probe by about a factor of ten compared to existing STEMs. Its operation is greatly assisted by newly developed autotuning software which measures all the aberration coefficients up to fifth order in less than one minute. We conclude by discussing the present limits of aberration-corrected STEM, and likely future developments.     

An evaluation of the usefulness of air-drying biological samples from tetramethylsilane in preparation for scanning electron microscopy.

A survey was done, using a limited number of animal, plant and insect samples, to evaluate the quality of structural preservation obtained when chemically fixed tissue is air-dried from tetramethylsilane (TMS). Comparisons were made with critical point drying (CPD) and air-drying from acetone (Controls). CPD samples showed good structural preservation in all cases. For some animal tissue, TMS and Control samples showed structural preservation comparable to CPD. In other animal tissues the order of structural preservation was CPD greater than TMS greater than Controls. Air-drying caused gross distortion in the botanical samples.