微缩投影系统的垂轴放大率测量

考虑有限距光学系统的成像质量与系统垂轴放大率相关,本文提出了基于系统波像差检测的垂轴放大率测量方案。以给定的光学系统中像平面位置与物平面位置满足高斯公式和牛顿公式的原理为出发点,通过系统波像差中离焦量的变化监控物点移动微小量后像点的移动距离。然后,对牛顿公式或高斯公式微分导出轴向放大率,最终求出系统垂轴放大率。建立了垂轴放大率测量模型,给出物点的微小位移量和初始离焦量的选取标准,并系统地分析了光学元件形位公差和像点定位精度对垂轴放大率测量结果的影响。搭建了基于点衍射干涉仪的微缩投影系统波像差检测平台,测量了系统的垂轴放大率。实验显示,系统垂轴放大率的测量值与理论值的偏差优于0.24%,验证了提出的垂轴放大率测量方法的可行性和理论分析的准确性。     

Video microscopic image processing facilitates the evaluation of light microscopic autoradiography at high magnification

Light microscopic autoradiographs of H-thymidine labelled unstained semithin sections of Xenopus laevis embryonic nuclei were examined with conventional Nomarski differential interference contrast, phase-contrast and video microscopy. Whereas at low magnification it was possible to obtain a photograph of the nuclear structure and the silver grains in one focal plain, at high magnification, with small depths of focus, a satisfactory image was not attainable. Therefore, we stored the images of the two different focus levels with a digital image processing system and combined both images by an arithmetic operation. This video microscopic technique allows the use of high magnification light microscopy with oil immersion objectives and the application of additional electronic contrast enhancing methods for an adequate and rapid analysis of light microscopic autoradiographs.     

Digital image tiles: a method for the processing of large sections

Segmentation of large areas of light microscopic slides into N by N fields, and each of these fields into M digital image tiles, allows the scanning, storage and digital processing of large images. Any of the original N² fields or composites of M adjacent tiles can be recalled to the video display for analysis. Developed procedures for use on a microscope equipped with a precision scanning stage allow registration of the image coordinates (X-Y) for any original or composite field and the alignment of one of these fields along the depth (Z) axis by means of external, machined fiducial marks in serial sections. To facilitate work whenever unavoidable, we have incorporated methods for digital image panning and zooming (changes of magnification) and discuss their use and implications.     

Weak-beam observation of dislocation loops in silicon

Weak-beam microscopy has been used to examine the dislocation loops formed when ion implanted silicon is annealed in the temperature range 900–1300 K. The extinction distances of about 10 nm, resulting from the use of large deviation parameters S' enable stacking fault fringes of 4nm spacing to be resolved in faulted loops. The projected shape of the dislocation loops and the variable contrast along the perimeter of the bounding partial dislocation enables the habit planes of the dislocation loops to be determined from inspection. These together with the width of the dislocation image, which is about 3 nm enables the type of loop to be characterized completely from a single micrograph.     

Weak beam under convergent beam illumination

The weak beam technique is now used widely for the determination of stacking fault energies, in particular for intermetallic alloys, and the accuracy of the approach is critically dependent upon the reliability of the relationship between the image and the actual position of the dissociated dislocations. Examining as a model case a dislocation dissociated into two Shockley partial dislocations in Cu at 100 kV for orientations ranging through the g(3g) weak beam condition, image simulations are used to explore the accuracy to which the true spacing between the partial dislocations can be determined from the spacing measured on the image as a function of the dislocation character, the foil thickness, the dislocation depth in the foil, the diffraction condition and the beam convergence. It appears that for image simulations and for the given conditions a beam convergence of about 5 mrad allows to greatly improve the accuracy, and that beam convergence must be taken into account quantitatively when deducing the true partial dislocation spacing as it is the principal parameter controlling the precision in this type of measurement.     

Synergistic effects of anisotropy and image force on TEM diffraction contrast of dislocation loops

Based on column approximation (CA) assumption, many-beam Schaeublin–Stadelmann diffraction equations are employed for simulating the transmission electron microscopy (TEM) diffraction image contrast of dislocation loops within thin TEM foil of finite thickness, and two beam and many beam diffraction conditions are compared. Moreover, the effects of materials anisotropy and free surface relaxation induced elastic fields distortion of dislocation loops on the black-white image contrast are specially focused. It is found that anisotropy has a remarkable impact on the TEM image contrast of dislocation loop, and free surface relaxation induced image forces can change the black-white contrast features when dislocation loops are near TEM foil free surfaces. Thus, in order to make reliable judgment on the nature of defects, effects of free surface and anisotropy should be included when analysing irradiation induced dislocation loops and other type of defects in in-situ electron, proton, heavy-ion irradiation experiments under TEM environments.     

The use of quadrats and test systems in stereology,including magnification corrections

At present a model-free, design-based theory of unbiased estimation, and a model-based one of linear unbiased estimation of minimum variance, are available for stereology. The main developments rest upon the nested scheme {section (quadrat)}, whence the raw data are expressible in terms of area, length and number. The main aim of this paper is to complete the available model-based theory by introducing the step in which sections are analysed by point-counting via coherent test systems (CTSs). Using this development, the stereologist should be able to handle raw point and intersection counts optimally, in order to find the best estimator of a ratio R in a given specimen in a wide range of circumstances. The latter include, for instance, the use of different CTSs on different sections and of double CTSs on each section, as well as the case—(not uncommon in electron microscopy)—in which different sections from the same sample are observed at slightly different magnifications but analysed by quadrats (via automatic or semi-automatic image analysers, for instance), or CTSs of fixed sizes. The main conclusion pertaining to the latter case is that the estimators obtained via section-wise magnification corrections are in general superior to those corrected via a global, average magnification. In order to illustrate the methodology, a synthetic numerical example, and a real one, are given.     

Application of Monte Carlo modelling in the measurement of photomask linewidths at the national physical laboratory

A scanning electron microscope (SEM) fitted with a helium-neon laser interferometer is used to measure the widths of features on photomasks. In this way the magnification of the SEM can be known very precisely. Algorithms which use the backscattered electron (BSE) signal, yielding good measurement repeatability, have been developed, but in order to be able to relate measurements made on the image to the physical dimensions of the artefact, it has been necessary to model the image formation process. The modelled predicted offsets to be applied to the experimental measurements are governed largely by the angle of the sloping sides of the chromium edges of photomask lines; knowing this angle, it is possible to use a simple geometric relation to calculate what offset should be applied.     

Subsurface Zone in Aluminium Studied by Positron Lifetime Spectroscopy

The subsurface zone in the well-annealed pure 99.999% aluminium exposed to the sliding of a graphite pin was studied using positron lifetime spectroscopy. This experimental method allowed to detect the dislocation lines, dislocation lines with opposite jogs and single vacancies that occur during sliding. The type of defect changes upon increase of the sliding time and depends on the distance from the damaged surface. It was established that the total depth of defect distribution depends on the applied load and extends from 150 to 450 m.     

基于重心法的螺旋线螺距测量系统

介绍成象放大法螺旋线螺距测量系统,采用线阵CCD图像传感器,采集螺旋线放大图像,经高速模数转换器转换成数字信号,存入双端口RAM。提出了对图像数据进行一阶微分并求其局部重心点作为其边缘特征点,以提高测量稳定性和测量精度。     

Determination of a misfit dislocation complex in SiGe/Si heterostructures by image deconvolution technique in HREM

The core structure of a dislocation complex in SiGe/Si system composed of a perfect 60 degrees dislocation and an extended 60 degrees dislocation has been revealed at atomic level. This is attained by applying the image deconvolution technique in combination with dynamical diffraction effect correction to an image taken with a 200kV field-emission high-resolution electron microscope. The possible configuration of the dislocation complex is analyzed and their Burgers vectors are determined.     

TEM纳米尺度石墨标样的制备

透射电镜的长度标尺或公称放大倍数是判断试样中组织细节尺寸的依据,需要应用纳米级长度标样进行校准。本文介绍了一种用石墨制备透射电镜专用纳米尺度标样的方法,对石墨的X射线衍射分析以及对石墨标样的TEM高分辨像和电子衍射分析表明,标样中石墨的高分辨像为（002）晶面的点阵像,其晶面间距为0．342nm,可作为纳米尺度的参照材料。本文对使用纳米尺度标样校正ETEM标尺的基本方法进行了简要讨论。     

Correlation analysis of digital images of flows with subpixel accuracy

New algorithms for processing noisy specklegrams are described which allow quantitative diagnostics of the microstructure of shock-wave flows with subpixel accuracy with the use of statistical analysis of the speckle fields recorded numerically and perturbed by refraction in the studied flows. The developed software makes it possible to recover up to 10,000 vectors of deflection angles of the probing radiation in a two-dimensional region 20 × 30 mm in size in a speckle field image with a magnification M = 1.     

A simple 2D composite image analysis technique for the crystal growth study of L‐ascorbic acid

This work was destined for 2D crystal growth studies of L‐ascorbic acid using the composite image analysis technique. Growth experiments on the L‐ascorbic acid crystals were carried out by standard (optical) microscopy, laser diffraction analysis, and composite image analysis. For image analysis, the growth of L‐ascorbic acid crystals was captured as digital 2D RGB images, which were then processed to composite images. After processing, the crystal boundaries emerged as white lines against the black (cancelled) background. The crystal boundaries were well differentiated by peaks in the intensity graphs generated for the composite images. The lengths of crystal boundaries measured from the intensity graphs of composite images were in good agreement (correlation coefficient “r” = 0.99) with the lengths measured by standard microscopy. On the contrary, the lengths measured by laser diffraction were poorly correlated with both techniques. Therefore, the composite image analysis can replace the standard microscopy technique for the crystal growth studies of L‐ascorbic acid.     

Why horizontal field width?

Use of field width rather than “magnification” as an indicator of scale gives the advantage that the caption to an illustration does not need to be changed if the magnification is changed for technical reasons during the printing process. The commonly used “micron bar” has the same advantage, but it is argued here that the use of a linear scale marker encourages the tendency to measure features from a single projection of the object. Most scanning electron micrographs portray rough surfaces, and linear distances need to be computed from stereophotogrammetric measurements. Our opinion is that micron bars should only be added where they can be used in a valid sense to make measurements. Stating the width of the field of view scanned in an SEM image gives an adequate idea of scale, without implying that one may proceed to derive accurate measurements without more elaborate procedures.     

Atomic configuration in core structure of Lomer dislocation in Si0.76Ge0.24/Si

The core structure of a Lomer dislocation in SiGe/Si system has been revealed at atomic level. This is attained by applying the image deconvolution technique in combination with dynamical diffraction effect correction to the high-resolution image taken with a 200 kV field-emission gun high-resolution electron microscope. The Lomer dislocation has a Hornstra-like core. The contrast of the image simulated on the basis of derived atomic configuration is in agreement with that of the experimental image.     

Dissociation of basal dislocations in hexagonal barium titanate

Dislocation substructure in hot-pressed hexagonal BaTiO₃ ceramics was analysed by transmission electron microscopy. Two dislocation networks each consisting of dissociated half-partials were determined for the Burgers vectors ( b ) using the g · b  = 0 effective invisibility criteria, and the true directions ( u ) by trace analysis. Each of the networks contains three partial nodes that are in the form: 1/3[010]+1/3[100]+1/3[100]+1/3[100] = 0, where four partials meet at a point and the Burgers vectors are conserved, as analysed by the weak-beam dark field technique. Basal dislocation with b _b = 1/3<110> is dissociated into two prism plane half-partials with b _hp = 1/3<100> by: 1/3<110> → 1/3<010> + 1/3<100>. Dissociation of basal dislocation by a glide mechanism creates a stacking fault when shear occurs along <100> in the c-layer of (000l), where l = 1, 3, 4 and 6, of the (chc)₁(chc)₂ (or (CBC)(ABA)) stacking sequence. The slip system of 1/3<110>(0001) in hexagonal BaTiO₃ has been activated at 1300 °C by hot-pressing under ∼25.8 MPa. Plastic flow contributing to the densification of hexagonal BaTiO₃ ceramics occurs through glide of half-partials in the basal plane by a glide-controlled dislocation glide mechanism. Dislocation motion governed by the Peierls mechanism, where velocity is determined by both correlated and uncorrelated double-kink nucleation on two half-partials, is discussed.     

Noise reduction in high-magnification micrographs by soft focus printing and digital image processing

Soft focus printing of micrographs, using screens of opaque material with 10–15 lines/cm, reduced contrast due to noise but preserved all other contrasts and all structural details. Appropriate screens generated diffraction fringes of a spacing similar to the distance of the noise structures. The superimposition of fringes and image produced a diffusion effect which reduced only the contrast of the noise background. Blurring, screening or fogging were not effective or suitable for photographic micrograph processing. Soft focus printing improved recognition of weak high magnification contrasts in SEM micrographs of uncoated, gold decorated, and chromium coated cell surfaces of glomerular endothelium in mouse kidney slices. Effects similar to the optical diffusion were obtained by digital image processing using weighted low pass filters.     

A prototype system of three-dimensional non-contact measurement

A prototype 3D measurement system is proposed in this paper which consists of a 1D laser displacement sensor, a 2D image system and a servo controlX,Y-table. The laser sensor and CCD camera are installed on theZ-axis perpendicular to theX,Y-table. The image-processing system employs the adaptive resonant theory (ART) neural networks to classify the outer shape of the measured object. The edge values of the object are then obtained by using the image processing procedures of sliding, stretching, edge enhancement and binary disposal. The 2D dimensions of the object are searched by employing the Hough theory based upon the edge values. The 3D dimensions of the object are measured and assembled by combining theX,Y-coordinates of the table and the scanning results of the 1D laser for the height of theZ-axis. A 3D plaster model is chosen as the specimen for non-contact measurement to verify the feasibility of this approach. The limitations and resolution of the 3D measurement of this system are discussed.     

The Austenite/Ferrite Interface In A Duplex Alloy Steel: Structure And Associated Diffraction Effects

This paper describes the structure of the austenite/ferrite interface in a duplex alloy steel. Specifically, it is shown that a single periodic set of dislocations exists in this interface. This dislocation array can act as a diffraction grating, and the extra reflections observed in selected area diffraction patterns are shown to be consistent with the dislocation structure observed in the image mode.