材料微观分析光学原理

1、电子显微分析Electron MicroscopySun YaUniversityThe center for nanotech researchLight Microscopes v.sElectron Microscopes2Electron Micrscopy, SYSU, S RenSept.2012Optic microscopy3Electron Micrscopy, SYSU, S RenSept.2012像的元素色彩明暗对比（衬度）4Electron Micrscopy, SYSU, S RenSept.2012增强衬度的方法样品表面腐蚀，增加不同组织之间反射方向的差别（晶界及

2、点阵缺陷选择腐蚀、物相选择腐蚀、点阵取向选择腐蚀等）改变光路，选择性成像。（明场、暗场像，偏振光成像，掠射光成像等）施加滤色片5Electron Micrscopy, SYSU, S RenSept.2012Bright field image6Electron Micrscopy, SYSU, S RenSept.2012Dark field image7Electron Micrscopy, SYSU, S RenSept.2012Tolanskyerference Contrast完整结构导致的衬度8Electron Micrscopy, SYSU, S RenSept.2012Volu

3、me fractionArea fraction9Electron Micrscopy, SYSU, S RenSept.2012Line fraction10Electron Micrscopy, SYSU, S RenSept.2012Pofraction11Electron Micrscopy, SYSU, S RenSept.2012成像的三个特质 像的分辨率 Higher resolution 景深（场深）Higherdepth of field HigherDepth of focus12Electron Micrscopy, SYSU, S RenSept.20121），分辨率1

4、3Electron Micrscopy, SYSU, S RenSept.20121）分辨率 Airys ringsDiffraction of a wave by any circularrture leadsto a set of cones, which appear as concentric rings when imaged.The centralense spot (the Airy Disc) contains84% of the totalensity.14Electron Micrscopy, SYSU, S RenSept.2012Critical distance rd

5、15Electron Micrscopy, SYSU, S RenSept.2012像分辨率Resolution of imagination 0.61N.A.r最小分辩距：d数字孔径 N.A.=n Sin n= refractive index of the medium.=wavelength of the light.=half the acceptance angle of the lens.透镜孔径角 2Electron Micrscopy, SYSU, S RenSept.201216有效放大倍数人眼最小分辩距离 L0.2 mm有效放大倍数MeMe * rd L0.2 mmTypi

6、cally , rd =0.2 um,Me = 100017Electron Micrscopy, SYSU, S RenSept.2012Me 0.2 mm/ rdSizes of cells and their components drawn on alogarithmic scale, indicating the range ofreadily resolvable objectshe light andelectron microscope.18Electron Micrscopy, SYSU, S RenSept.20122），场深（景深） Depth of field Dobi

7、croscopy,therangeofdistanceatthespecimen parallel to the illuminating beam inwhich the object appears to be in focus.19Electron Micrscopy, SYSU, S RenSept.2012影响景深的 相机与物体的距离距离越大，景深越大 聚焦的距离聚焦距离越大，景深越大 光阑的大圈）圈数值越大），景深越大光阑越20Electron Micrscopy, SYSU, S RenSept.2012景深与分辨率的关系高分辨率 大视角，大光阑大景深 小视角，阑21Electr

8、on Micrscopy, SYSU, S RenSept.20123），Depth of focusicroscopy,therangeofdistanceat the image plane (i.e. the eyece,camera,orphotographicplate)inwhich a well focussed object appears to be in focus.22Electron Micrscopy, SYSU, S RenSept.2012Spherical aberration 球差Spherical aberration arises because a thin lens brings rays at its periphery to focus at a shorterfocal distan