扫描电子显微镜和透射电子显微镜分析
透射电子显微镜介绍
对于材料研究用的TEM试样大致有三种类型： 经悬浮分散的超细粉末颗粒。 用一定方法减薄的材料薄膜。 用复型方法将材料表面或断口形貌复制下来的复型膜。
对支持膜的要求：
➢ 要有相当好的机械强度，耐高能电子轰击； ➢ 应在高倍下不显示自身组织，本身颗粒度要小，以提高样品分辨率； ➢ 有较好的化学稳定性、导电性和导热性。
二、透射电子显微成像
使用透射电镜观察材料的组织、结构，需具备以下两个前提： 一是制备适合TEM观察的试样，厚度100-200nm，甚至更薄； 二是建立电子图像衬度理论 像衬度是指电子像图上不同区域间光强度的差别。 透射电镜的像衬度来源于样品对入射电子束的散射。可分为：
衍射衬度：晶体薄膜试样显微图像 质厚衬度 ：非晶态试样图像
形貌+结构 空心结构
四、透射电镜得到的信息
晶格条纹+电子衍射
（1）量取两个晶面晶面之间的距离 （2）与标准卡片去比对，选择合适的面
四、透射电镜得到的信息
线扫 Line Scan 面扫 Mapping
EDS元素分析
四、透射电镜得到的信息
总
一般成像 模式
明场像 （BF） 暗场像 （DF）
微观形貌，厚度差异，尺寸大小 取向，分布，结构缺陷
在明场像情况下，原子序数较高或样品较厚的 区域在荧光屏上显示较暗的区域。在暗场像情 况下，与明场像相反。
质量厚度衬度：对于无定形或非晶体试样，电子图像的衬度是由于试样各 部分的密度ρ和厚度t不同形成的，简称质厚衬度。
成像的影响因素
➢ 电子数目越多，散射越厉害，透射电子就越少，从而图像就越暗 ➢ 样品厚度、原子序数、密度对衬度也有影响，一般有下列关系：
电子显微分析
（3）电子光学可仿照几何光学把电子运动轨迹看成射线，并由此引入一 系列的集合光学参数来表征电子透镜对于电子射线的聚焦成像作用。
但应注意电镜中的电子光学：
（1）是真空中的静场，即电、磁场与时间无关，且处于真空中。
（2）入射的电子束轨迹必须满足离轴条件：
|
r
|2
0
(1)
dr
2
1
(2)
dz
• 旋转对称的 磁场对电子束有聚焦作用，能使电子束聚焦成像。产生这 种旋转对称非均匀磁场的线圈装置就是磁透镜。
• 目前电子显微镜中使用的是极靴磁透镜，它是在短线圈、包壳磁透镜的 基础上发展而成的。
• 磁透镜的作用使入射电子束聚焦成像。几种磁透镜的作用示意图如下：
• 磁透镜与静电透镜的比较：
磁透镜与静电透镜都可以作会聚透镜，但现代所有的透射电镜除电子光源外都 用磁透镜做会聚镜，主要因为：一是磁透镜的焦距可以做得很短，获得高 的放大倍数和较小的球差；二是静电透镜要求过高的电压，使仪器的绝缘 问题难以解决。
1. 电子在静电场中的运动
电子在静电场中受到电场力的作用将产生加速度。初速度为0的自由电 子从零电位到达V电位时，电子的运动速度v为：
v 2eV
(10)
m
即加速电压的大小决定了电子运动的速度。当电子的初速度不为零、
运动方向与电场力方向不一致时，电场力不仅改变电子运动的能量，
而且也改变电子的运动方向。如图1
近一、二十年，出现了联合透射、扫描，并带有分析附件的分析电镜。 电镜控制的计算机化和制样设备的日趋完善，使电镜成为一种既观察 图象又测结构，既有显微图象又有各种谱线分析的多功能综合性分析 仪器。
80年代后，又研制出了扫描隧道电镜和原子力显微镜等新 型的电子显微镜。 我国自1958年试制成功第一台电镜以来，电镜的设计、制 造和应用曾有相当规模的发展。主要产地有北京和上海。 但因某些方面的原因，国产电镜逐渐被进口电镜取代。
第7章 电子显微分析
电磁透镜
• 电子显微镜可以利用电场或磁场使电子束聚焦成像，其中 电子显微镜可以利用电场或磁场使电子束聚焦成像， 用静电场成像的透镜称为静电透镜， 用静电场成像的透镜称为静电透镜，用电磁场成像的称为 电磁透镜。 电磁透镜。 • 电磁透镜一般由三级电磁透镜组成，即第一聚光镜、第二 电磁透镜一般由三级电磁透镜组成，即第一聚光镜、 聚光镜和末级聚光镜（即物镜）。 聚光镜和末级聚光镜（即物镜）。 • 主要功能是依靠透镜的电磁场与运动电子的相互作用将电 子枪中交叉斑处形成的电子源逐级汇聚成为在样品上扫描 的极细电子束（电子探针）。 的极细电子束（电子探针）。 • 末级透镜也叫物镜，除了汇聚功能外，它还起到使电子束 末级透镜也叫物镜，除了汇聚功能外， 聚焦于样品表面的作用。另外，每一级透镜上都装有光阑， 聚焦于样品表面的作用。另外，每一级透镜上都装有光阑， 二级透镜通常是固定光阑， 一、二级透镜通常是固定光阑，主要是为了挡掉一大部分 无用的电子，防止对电子光学系统的污染。 无用的电子，防止对电子光学系统的污染。末级透镜下方 紧连样品室。 紧连样品室。
构造与成像原理
照明由电子枪、 照明由电子枪、聚光镜和 相应的平移对中、倾斜调 相应的平移对中、 节装置组成。 节装置组成。 作用是提供一束亮度高、 作用是提供一束亮度高、 照明孔径小角小、 照明孔径小角小、平行度 束流稳定的照明源。 好、束流稳定的照明源。 为满足明场和暗场成像需 照明束可在2° 要，照明束可在 °～3° ° 范围内倾斜。 范围内倾斜。
构造
• 电子光学系统主要由电子枪、电磁聚光镜、光阑、样品室等 电子光学系统主要由电子枪、电磁聚光镜、光阑、 组成。 组成。 • （1）电子枪 ） 扫描电镜的电子束应具有较高的亮度和尽可能小的束斑 直径。 直径。 • （2）电磁透镜 ） SEM中电磁透镜都不作成像透镜用，而是作为聚光镜用， 中电磁透镜都不作成像透镜用， 中电磁透镜都不作成像透镜用 而是作为聚光镜用， 它们的功能只是把电子枪的束斑逐级聚焦缩小， 它们的功能只是把电子枪的束斑逐级聚焦缩小，使原来直径 约为50µm的束斑缩小成一个只有数个纳米的细小斑点。扫描 的束斑缩小成一个只有数个纳米的细小斑点。 约为 的束斑缩小成一个只有数个纳米的细小斑点 电子显微镜一般都有三个聚光镜， 电子显微镜一般都有三个聚光镜，前两个聚光镜是长焦距的 弱磁透镜。末级透镜也叫物镜，除了会聚功能外， 弱磁透镜。末级透镜也叫物镜，除了会聚功能外，它还起到 使电子束聚焦于样品表面的作用。 使电子束聚焦于样品表面的作用。
纳米材料的电子性能测试方法
纳米材料的电子性能测试方法随着纳米科技的快速发展，纳米材料作为一种新兴材料，在能源、光电子、生物医学等领域展现出了巨大的应用潜力。
而对纳米材料的电子性能进行准确测试和评估，则是研究和应用纳米材料的关键之一。
本文将重点介绍几种常用的纳米材料电子性能测试方法。
1. 透射电子显微镜(TEM)观察法透射电子显微镜是一种能够观察到材料原子级别细节的高分辨率显微镜。
通过TEM观察，可以对纳米材料的晶体结构、晶格缺陷、晶粒尺寸等进行直接观测和表征，从而间接评估纳米材料的电子性能。
虽然该方法不直接提供材料的电子导电性等信息，但是可以作为纳米材料结构特性与性能之间的关联。
2. 扫描探针显微镜(SPM)测试法扫描探针显微镜是一种基于原子力、电导和磁力等相互作用的表面显微镜，可以实现对材料表面形貌和电子性能的同时测试。
通过探针与纳米材料表面相互作用的信号，可以获得纳米材料的电子导电性、介电性、磁性等信息。
常用的SPM技术包括原子力显微镜(AFM)和电子能谱显微镜(ESPM)等，这些方法具有高分辨率、无需制备样品等优点。
3. 微焦电子能谱分析(XPS)测试法微焦电子能谱分析是一种通过测量材料表面电子能量分布来分析其成分和化学状态的表征方法。
通过X射线照射材料表面，可以激发出材料表面的电子，然后测量电子的能量分布和强度，从而得到纳米材料的化学成分和电子态信息。
XPS可以提供材料的表面成分、化学键状态、电子离子态以及原子之间的键长等信息，对于纳米材料的表面化学性能和光电子性能的研究具有重要价值。
4. 电化学测试法电化学测试是通过测量材料在外加电场或电流作用下的电流响应来评估其电子性能的方法。
对于纳米材料而言，电化学测试可以用于评估其导电性、电化学储能性能等方面的性能。
常见的电化学测试方法包括循环伏安法、电阻率测试、电化学阻抗谱等。
通过这些测试技术，可以了解纳米材料的电荷传输、传导机制以及电化学反应特性。
总结起来，纳米材料的电子性能测试方法包括透射电子显微镜观察法、扫描探针显微镜测试法、微焦电子能谱分析测试法以及电化学测试法等。
材料现代分析测试方法
材料现代分析测试方法材料的现代分析测试方法是为了研究材料的组成、结构、性质以及相应的测试手段。
通过分析测试方法，我们可以深入了解材料的特点，进而为材料的研发、优化和应用提供有效的数据支持。
下面将介绍几种常用的材料现代分析测试方法。
一、质谱分析法质谱分析法是一种通过测量样品中不同质荷比（m/z）的离子的相对丰度来确定样品组成和结构的分析方法。
质谱分析法适用于分析有机物和无机物。
其优点是能快速分析出物质组成，提供准确的质量数据，对于结构复杂的样品仍能有效分析。
二、核磁共振（NMR）谱学核磁共振谱学是一种通过测量样品中核自旋与磁场相互作用的现象来分析样品结构和组成的方法。
不同核的共振频率和强度可以提供关于样品分子结构和组成的信息。
核磁共振谱学适用于有机物和无机物的分析。
由于从核磁共振谱图中可以获得丰富的结构信息，所以核磁共振谱学被广泛应用于有机化学、药物研发和材料科学等领域。
三、红外光谱学红外光谱学是一种通过测量样品对不同波长的红外辐射的吸收情况来分析样品结构和组成的方法。
不同官能团在红外区域会有特定的吸收峰位，因此红外光谱能提供有关样品中化学键和官能团的信息。
红外光谱学适用于有机物和无机物的分析。
它具有非破坏性、快速、易于操作等特点，在化学、生物和材料科学领域得到了广泛应用。
四、X射线衍射（XRD）X射线衍射是一种通过测量样品对入射X射线的衍射现象来研究样品结构和晶体结构的方法。
不同物质的晶格结构具有不同的衍射图样，通过分析衍射图样可以获得样品的晶体结构信息。
X射线衍射适用于分析有晶体结构的材料，如金属、陶瓷、单晶等。
它能提供关于晶体结构、晶粒尺寸和应力等信息，被广泛应用于材料科学、地质学和能源领域。
五、扫描电子显微镜（SEM）和透射电子显微镜（TEM）扫描电子显微镜和透射电子显微镜是一种通过聚焦电子束对材料进行观察和分析的方法。
扫描电子显微镜主要用于获得材料的表面形貌、颗粒分布和成分分析。
透射电子显微镜则能提供材料的内部结构和界面微观结构的信息。
电子显微镜的成像原理及应用
电子显微镜的成像原理及应用引言电子显微镜是研究微观世界的一种重要工具。
电子显微镜利用高速电子束与物质相互作用的原理进行成像，具有高分辨率、大深度、高增强等特点。
电子显微镜已经广泛应用于物理、化学、材料科学、生物学等领域，成为科研中不可或缺的重要仪器之一。
本文将从电子显微镜的成像原理和应用两个方面来进行探讨。
电子显微镜的成像原理电子显微镜的成像原理是利用电子与物质相互作用的本质进行成像。
根据电子束的物理性质，电子显微镜可以分为透射电子显微镜（TEM）和扫描电子显微镜（SEM）两种类型。
1.TEM的成像原理透射电子显微镜的成像原理是利用电子在物质中透过和散射的规律进行成像。
电子束照射样品后，会发生透射、散射、反射等现象。
其中，透射电子被样品中原子核和电子云所散射，使被散射电子的方向和传播速率发生变化，形成交叉散射和多次散射。
在透射电子显微镜中，电子束经过样品后，被成像系统所收集，得到的是强度分布图。
通过对强度分布图的分析，我们可以还原得到样品的组成、结构、缺陷和微观形貌等信息。
2.SEM的成像原理扫描电子显微镜的成像原理是利用不同材料对电子的不同散射特性成像。
扫描电子显微镜中，电子束由电子枪发射，经过电子透镜系统加速并聚焦成为很小的电子束，然后，电子束通过样品表面，与样品相互作用，产生了二次电子、退火电子、背散射电子等电离粒子，这些电离粒子产生的信号经过检测和预处理后可形成像。
通过Si(Li)和NaI(TI)等探测器的辐射测量，我们可以将这些像转化为电信号，进而进行成像。
电子显微镜的应用电子显微镜在研究微观世界、分析材料的结构、形貌和性质方面已经得到广泛应用。
1.材料科学领域的应用电子显微镜在材料科学领域的应用有很多。
通过电子显微镜的成像技术，我们可以了解材料的孔洞结构、晶格结构、的缺陷、组成、性质等方面的信息。
同时，电子显微镜还可以研究材料的晶体生长、相变、热力学性质等方面的行为，为制备新材料提供了重要的研究支持。
扫描电子显微镜的原理和应用
扫描电子显微镜的原理和应用扫描电子显微镜是一种利用电子束扫描样品表面并对扫描到的电子信号进行成像的高分辨率显微镜。
与光学显微镜不同，扫描电子显微镜利用电子束通过透镜和场控制技术非常高效地聚焦并成像，以获得超高分辨率的成像效果，以及大量的表面和物质信息。
扫描电子显微镜的原理扫描电子显微镜的核心是电子光源，它利用热发射、光电发射或场致发射等方式产生的电子束，经过一系列的焦距透镜、偏转线圈、探针控制和信号采集系统组成。
扫描电子显微镜的成像原理和传统光学显微镜略有不同。
它不是通过透镜去聚焦光线来成像，而是通过利用电子作用在样品表面的电磁场和电子-物质相互作用来实现的。
扫描电子显微镜利用电子束在样品表面扫描出一个小点，由电子-物质相互作用产生的电子信号被收集并转化成电子图像数据，然后利用计算机对数据进行图像处理，形成高分辨率的显微成像，以及其它相关物化信息。
扫描电子显微镜的应用扫描电子显微镜因其超高分辨率和强大的化学和物理分析功能而广泛应用于许多领域。
在材料科学领域，扫描电子显微镜广泛用于各种材料的表面和微结构分析，包括晶体结构、颗粒形貌、纳米结构、原子局部构型等。
其中，扫描透射电子显微镜（STEM）可以提供比常规扫描电子显微镜更高的结构分辨率，可用于对材料和生物样品的超高分辨率成像和分析。
在生物科学领域，扫描电子显微镜广泛应用于生物样品的形态与结构分析，如细胞器、膜结构、细胞外矩阵等。
同时，扫描电子显微镜也被用于对代谢过程和细胞凋亡等重要生物过程的研究。
在微电子制造和半导体工业中，扫描电子显微镜用于分析芯片表面的纳米结构和性能，以及其他半导体材料和器件的研究和开发。
在环境科学领域，扫描电子显微镜可用于分析环境污染物的化学成分和形态，如粉尘、气溶胶、烟尘等，有助于研究它们的来源、形成机制和生物毒性。
结论扫描电子显微镜是一种高分辨率的显微镜技术，具有广泛的应用前景和重要的科学意义。
不仅能够提高我们对材料、生物样品、半导体和环境的理解，而且也在未来的许多领域中发挥着重要的作用。
扫描透射电子显微镜模式分析
A general introduction to STEM detector1. BF detectorIt is placed at the same site as the aperture in BF-TEM and detects the intensity in the direct beam from a point on the specimen.2. ADF detectorThe annular dark field (ADF) detector is a disk with a hole in its center where the BF detector is installed. The ADF detector uses scattered electrons for image formation, similar to the DF mode in TEM.The measured contrast mainly results from electrons diffracted in crystalline areas but is superimposed by incoherent Rutherford scattering.3. HAADF detectorThe high-angle annular dark field detector is also a disk with a hole, but the disk diameter and the hole are much larger than in the ADF detector. Thus, it detects electrons that are scattered to higher angles and almost only incoherent Rutherford scattering contributes to the image. Thereby, Z contrast is achieved.In addition, there is the option to install a Secondary Electron Detector above the sample like in a SEM and thereby to obtain additional morphological information.4. The central DF and BF mode in normal TEMIn normal TEM, we also mentioned the DF and BR mode. Actually, they are different with ADF and BF mentioned here completely. In normal TEM, the direct transmitted beam is blocked by the aperture and the diffracted beam is allowed passing. When the diffracted beam hits thescreen and forms a image which is called as DF. Otherwise, diffracted beam is blocked with aperture and transmitted beam forms BR image.However, in STEM mode, they are totally different because the beam on sample is cone-shaped beam rather than parallel light.STEM模式和TEM模式的对比图Z-contrast actually uses an annular detector which can only collect the scattered electrons outside the beam cone. That is to say, the transmitted electrons inside beam cone are involved. This is good thing for other imaging mode because diffraction contrast was avoided and the imaging only has dependence on atomic structure. This imaging mode is called as STEM-HAADF. Here, two issues are not addressed yet. One is whether STEM-BF and STEM-ADF imaging involves diffraction contrast. Personally, I think STEM-ADF should involve phase contrast and Z contrast. For STEM-BR, phase contrast is greatly involved. However, in case of HAADF, only Z-contrast works.Camera Length affects the Inner Collection angel. In our TEM, when camera length is 11 cm, the inner collection angel is 60 mrad. Once the camera length reducing to 5 cm, the inner collection angel is 110 mrad. Therefore, the collection angle is controlled by the camera length. Whoaffects the camera length? According to equation (L=f*Mp*M l) where f is the focal distance of objective lens (f is related with the excited current, acceleration voltage, the number of coil), Mp and M l are the magnification of projective lens and intermediate lens respectively. Experimentally, the f can be changed significantly through adjusting the excited current. Besides, in order to change the camera length, you also can change the excited current of projective lens or intermediate lens. When inner collection angle is bigger than 100 mrad, the Rutherford scattering dominates the imaging.The inner angles for HAADF detectors are at least three times the angle of electron-probe-forming aperture. In many cases of HAADF imaging, the annular detection angle was practically set to be 60 - 170 mrad due to the limitation of combinations between aperture sizes and camera lengths. Above image shows the positions of the detectors which can be installed in a STEM system. Depending on the scattering angle of the transmitted electrons, various signals can be detected as a function of the position of thescanning probe: BF (bright-field)-STEM, DF (dark-field)-STEM or HAADF (high angle annular dark field)-STEM.The DF detectors are annularly shaped to maximize the collection efficiency and the range of the collected scattering angles can be adjusted through the magnification of the intermediate lenses.FEI HAADF detectorChapter 1. Introduction to STEMSome TEMs have scanning coils which allow them to be used as a scanning transmission electron microscope (STEM). In STEM, a conical electron beam is focused through the specimen by a lens in front of the specimen (C2 and the objective lens pre-field which is also called mini lens), as shown below.The optical configuration is roughly the same as simply forming an image of the filament by focussing C2 the very first experiment we did in the electron microscope. In fact, if your microscope has a twin objective lens including pre-field and backfield, the optics are a little bit more complicated, but lets start thinking about things as simply as possible.The small beam cross-over at the specimen plane is usually called an Electron Probe. Images can be formed by moving the probe across the specimen (by the double- deflection shift coils) and detecting the transmitted electrons, which are either on the optic axis (to form a bright-field (BF)image) or have been scattered to high angles, to form a dark-field image (DF).In order to make an image, we have to display the signal coming out of one or more detectors in some way. This is usually done on a slow-scan television screen (although it is nowadays also done by computer). The signal detected is used to modulate the intensity of the image on the display screen, while the scan of the display is synchronised accurately with the position of the probe on the specimen. Usually, the same scan generator is used to control both the x-y position of the small beam (or probe) shift deflection coils and the coils that control the display screen. The principle is the same as a conventional scanning electron microscope.A STEM doesn’t actually need any lenses below the specimen at all, because everything important happens before the electrons reach the sample. In practice, a TEM/STEM has all the usual objective lens and projector lenses below the sample (shown as a dotted box above), but in STEM mode these are just used to change the effective camera length (that is, the distance between the specimen and the detector plane). They can also be used to form an image of the electron probe.Although there are certain benefits of STEM imaging (which have not been generally been recognised until quite recently), the main advantage of this geometry is the fact that the probe can be used to irradiate a very small volume of specimen in order to obtain all sorts of other signals such as characteristic X-rays, Auger or secondary electrons, or electron energy-loss spectra. All these signals can be spatially resolved at a resolution corresponding to the width of the probe, thus allowing for high resolution micro- analysis. For the material scientist, analytical signals like these can be much more useful than simply images, say to identify the elements present in an inhomogeneous sample.Chapter 2.The Ronchigram（水纹相）Experiment: Load a test specimen of polystyrene spheres, shadow coated with gold particles on a carbon film. Line up the microscope as usual in normal TEM mode. Select the largest condenser aperture and centre it.Ask the demonstrator: Show me how to put the microscope into STEM mode, with the scan switched off. Please align the condenser lens, aperture and stigmators (消散器), and objective rotation centre (current and HT centre), so that I can see a reasonably well-aligned Ronchigram.Let’s start by not actually scanning the probe at all. Examine what we see on the phosphor screen at the bottom end of the electron microscope. The rays coming out of the sample have conical shape, formed by the condenser aperture, and this cone eventually hits the phosphor screen, where it forms a bright circle. The circle is called the 'Gabor hologram', the 'Ronchigram' or the 'central zero-order disc of the convergent beam electron diffraction pattern' depending on the context and who is talking about it. I'm going to call it the Ronchigram. It provides the best way of lining up a STEM, and it will also teach us a lot about electron lens aberrations.Experiment: Look at the Ronchigram. Start by going through focus on both C2 and the objective lens. Move the specimen.You will find that the Ronchigram looks pretty strange, a sort of fish-eye view of the specimen. Go through focus with either the objective or C2 (Note: the objective lens is the pre-field objective lens). If you want to increase the contrast, go up in spot size. Weird shapes move in and out with over focusing and under focusing. If the microscope is well aligned, the Ronchigram from an amorphous specimen should look something the next figure, which has been calculated in a computer:Well, why does the Ronchigram look like this? As a first approximation, what we should see is a shadow image cast by the specimen which reverses as we change the cross-over of the beam near the specimen, as shown below:When the beam is crossing over exactly at the specimen, there will be a burred mess over the whole disc (middle picture above). If the specimen has some feature, like the curly P above, then above and below focus we see a shadow of that feature cast onto the central disc, and magnified according to how far away the beam cross-over is above or below the specimen.Experiment: Turn C2 from a zero setting, slowly increasing its strength. You should see the image reversal. All this occurs at a rather low setting of C2. At higher settings, the Ronchigram may get focussed into a bright spot and undergo a second reversal. However, this reversal is to do with the way we are using the lower part of the microscope (below the specimen plane) to image the cone of illumination coming out of the specimen. Concentrate on the low settings of C2.In fact, the behaviour of image is much more complicated than the figure above suggests because of the effects of aberrations in the lens. Allsorts of aberrations may be present in C2, but these tend to over-focussinghigh angle beams (ones that pass well off-centre), bringing them to a premature focus, i.e. a focus that is nearer the lens than it should be.To understand this, first consider a perfect lens. A perfect lens, by definition, focuses all beams from the source to a single point, as shown below.If we have aberration presents, high-angle beams tend to be over-focussed, so that they focus at a plane above the plane of perfect focus, like this:How is this extra complication going to affect what we see in the Ronchigram? Start by thinking about just two sets of beams: two which are virtually 'paraxial' (which means that they are traveling very close the centre of the lens) and which therefore come to the correct focal point of the lens (a point which is called the Gaussian focus); and two which are at very high angle, or close to the very edge of the condenser aperture, as shown below.Now, when the probe-forming lens is highly over-focussed (which in this experiment means that C2 is moderately excited), all the beams,including the paraxial and high- angle beams, cross-over before they reach the specimen. What we see is just a shadow-image Ronchigram as we would expect, although there will be a slight change in magnification between areas near the centre of the Ronchigram and its edge.Similarly, when the lens is highly under-excited, we see a reversed shadow image, again slightly distorted in magnification. However, near focus there is a peculiar region which I have called the 'region of radial inversion' in the figure above. When the specimen is lying somewhere in this region (or the lens has been adjusted accordingly), paraxial beams are crossing below it, but high-angle beams are crossing above it. In the Ronchigram, the centre of the pattern has undergone a reversal; the edge of the pattern is still in the over-focused orientation.Experiment: On a well-aligned Ronchigram, focus C2 so that the magnification of the image is at maximum. Under-focus slightly and move the specimen. You should be able to find a condition where the centre of image moves in one direction, while the outer area moves in the opposite direction. If you do, then you are within the region of radial inversion. If all you can see are streaking effects and asymmetric stretching of areas of the Ronchigram, then the lenses have not been lined up properly, or the astigmatism in the condenser lens has not been corrected.Look again carefully at the artificial Ronchigram:There are two characteristic rings, which you should be able to see experimentally as well. When the focus is set within the region of radial inversion, there is a central circular area where we see just a normal shadow image at rather high magnification. There is then a ring where everything is streaked out in the radial direction: this is called the ring of infinite radial magnification. At a higher radius, there is a ring where everything is streaked out into a circular pattern: this is called the ring of infinite azimuthal magnification. We don't have to understand why this happens like it does - it is all to do with the mathematics of how much the rays miss Gaussian focus as a function of their angle through the lens.What is important is that the Ronchigram must be circularly symmetric if you want to get a good STEM image.Experiment: Put the C2 stigmators onto their coarsest setting, and change them by a large amount. Watch the Ronchigram as a function of C2 defocus, especially at or near Gaussian focus (i.e. when you can see a highly magnified blob at the centre of the Ronchigram). You should see streaking shapes, which are like ovals or figures of eight.If you can't see any of the effects we've talked about, then the lenses are not properly aligned. Let’s first discuss in more detail how the lenses are arranged.Chapter 3.Lens geometry in STEM mode on aTEMIn normal TEM mode, we have two cross-overs below C2, the lower one occurring within the objective pre-field, as shown in the elementary guide. One way of forming a probe would be to de-excite C2, as we did in the very first experiment in first section of the TEM guide, but then we still have a second cross-over which is happening somewhere odd within the pre-field.Greater flexibility and an optimized probe focus can be obtained by avoiding the cross-over within the objective pre-field. In practice, this is achieved by either lowering the overall objective excitation or (depending on the make of microscope) using another small lens within the upper part of the objective twin lens, which is called either a mini-condenser or mini-lens. When the machine is being run in normal TEM mode, this lens is run in the same sense as the objective, making the pre-field very strong. When STEM mode is selected, the mini-lens is WEAKENED (or switched off), and so it cancels out the pre-field to a certain extent.The next Figure illustrates conventional TEM imaging:Where the top lens is C2, and the two lower lenses represent the objective pre-field (and/or the objective lens pre-field boosted by a condenser mini-lens or objective mini-lens).Now when we go into STEM mode, most microscopes reduce theinfluence of the pre-field, so now the ray-diagram looks like this:Note that both C2 and the objective lens affect the focus of the electron probe. Because C2 is so weakly excited, you can see from the figure above that it will have a huge effect on the convergence angle of the illumination at the specimen plane. For this reason, many manufacturers fix the value of C2 in STEM mode. To obtain control of it, the user has to override the computer.Remember: In STEM, the only electron optics that matter all happen before the specimen. Alignments you made relating to TEM imaging, especially the objective focus (this is the backfield objective focus below the specimen) and stigmation, are useless in STEM mode. We must alter the objective lens (thus altering the pre-field above the specimen) and C2 to control the alignment. The relevant stigmators for STEM mode are the condenser stigmators, not the objective stigmators.Now that we know that two lenses are involved in the forming probe, we can work how to line them up with one another. The most sensitive mis-alignment arises from the double- deflection coils being on the wrong tilt setting. If the beam tilt is wrong, the beam from C2 passes into the objective pre-field off-axis and at an angle. It will come out below the specimen also at the wrong angle: this is most common reason for losing the beam in STEM or nano-probe mode at high camera lengths.The first thing to get right in STEM mode is therefore the objective rotation centre. The alignment is almost certainly not the same as for TEM, because the objective is in a completely different state, and we are aligning with respect to the pre-field, not the main body of the lens below the specimen. Similarly, the condenser aperture is almost certainly off-line, even if you lined it up in TEM mode.All the corrections are best done in the electron Ronchigram.Experiment:（A）Wobble the objective lens, and try to get the image moving in and out symmetrically with the condenser (we assume here that this is on line). As you alter the beam tilt (this should be the correction you are adjusting on the multi-function knobs when aligning in STEM mode), the whole Ronchigram will at the same time bodily move across the phosphor screen. That's because the conical beam cast by the condenser lens is rocking like a lever through the specimen, and moves all over the far-field plane, like the sweep of a torch beam. Start with a large condenser aperture. The aim is to get a stationary shadow image at the very centre of the disc you can see on the screen.Just get the rotation centre roughly right, stop the objective wobbling, and then change C2. (Remember that on most machines you may have over-ride the C2 setting). Is the Ronchigram going in and out symmetrically around a point at the centre of the condenser aperture? If not, shift the condenser aperture onto that axis. If in any doubt at all, leave the condenser aperture where it was correct for TEM imaging. You will not get a perfect STEM image, but neither will you lose the beam, which is very easy at this stage.Now go back and wobble the objective lens again. When both these centres are roughly co-incident with the condenser aperture, set C2 at the value you are going to use it in STEM mode.（B）Focus the objective to get the Ronchigram to 'blow up' into infinitive magnification at its centre. Adjust the condenser stigmators so that the Ronchigram changes symmetrically as a function of defocus. This takes some practice. (Remember that the objective stigmators, which are below the specimen, are useless in STEM mode, although you should try to set them roughly right in TEM mode before switching to STEM mode.)If in doubt, wait until you are in scanning mode and can see an image on the scanning monitors before you attempt to correct astigmatism. However, note that if the stigmators are wrong and you change them later, all the above alignments should be re-iterated if you want the best probe possible. Misalignment, tilt, astigmatism, defocus and spherical aberration (which is the thing that makes the Ronchigram look the way it does) are all just lens aberrations that add up and affect the focus of the probe. Change any one of these variables, and another one will no longer be optimal.（C）Whatever you do, don't try turn C2 so high that what you see on the phosphor screen reaches a focus. This is bound to look astigmatic - but don't correct the condenser stigmators in this condition. Set C2 at its STEM mode setting. Now focus the objective lens: in other words, change the focus until the Ronchigram magnification is a maximum (i.e. the intensity distribution 'blows up' at its centre). If there is astigmatism present, the Ronchigram will not 'blow up' into a uniform infinite magnification blob. Instead, it will look stretched in one direction at one setting of objective defocus, and stretched roughly at right-angles at another setting of defocus. Set the objective between these two extremes, and then correct the condenser stigmators, turning them so that whatever you see spreads more uniformly over the Ronchigram. If the stretching of the image gets more extreme, you're turning the stigmator the wrong way.As a general rule, for the best scanning probe resolution, you should select a condenser aperture size that just selects the middle 'flat' area of intensity in the Ronchigram when it is just in focus. 'Just in focus' means that as we decrease focus from above the beam cross-over setting, the very centre of the Ronchigram has just exploded into a blob, but has not yet become a clear inverted shadow image. Because changing spot size changes the value of C2 as well as C1 (in STEM mode), and this affects the angle ofconvergence at the specimen, the size of the condenser aperture needed to fulfill this condition may also change.Chapter 4.Pivot pointsBefore we begin to scan the probe to make a STEM image, it is essential to check the pivot points. (Sadly, this is not possible on all makes of machine because it is regarded as 'too difficult' by the manufacturers. However, you can usually obtain access to the control indirectly via the computer.) Think of the following diagram, where the pivot points are incorrectly adjusted:In an ideal world, the probe continues to point in exactly the same direction as it is scanned over the specimen by the beam shift coils. However, if the rocking point of the scan coils is wrong, the beam tilts as well as shifts (see introductory guide if you have forgotten the meaning of tilt and shift). This has two consequences: the Ronchigram moves relative to the detectors as the probe is scanned, and the magnification of the STEM image will not be calibrated. At worst, the beam may be only tilting, and not moving laterally at all, in which case the apparent magnification of the STEM image will be much higher than the nominal value. Note that this pivot point adjustment is quite different to the pivot point values in TEMmode. In the latter, we adjust for a stationary probe as a function of tilt; here we adjust for stationary tilt as a function of shift. We are aiming for shift purity.There are different ways of making this adjustment on different machines. It is essential to correct it for each spot size and/or objective/condenser combinations of setting. The way the beam shift interacts with the objective pre-field means that the degree of tilt can be strongly correlated to strength of the objective.Ask the demonstrator: How do I adjust the pivot points in STEM mode?If in doubt, one way of doing this is to assume the objective aperture is truly in the back focal plane of the objective lens (Usually, it is not quite in the back focal plane). If we pretend it is in the back focal plane, then a way of testing the pivot points is to select diffraction mode and observe the Ronchigram. Insert a small objective aperture (smaller than the Ronchigram), which should cast a shadow over the Ronchigram, and switch on the pivot point adjustment.If two objective apertures become visible, the diffraction lens is not focusing on the back focal plane; focus the diffraction lens until only one objective aperture is visible. Now remove the objective aperture and adjust the STEM pivot points until the two Ronchigrams are superposed. Note that in STEM mode, focusing the diffraction lens in diffraction mode does not mean making the beam make a sharp point (as in TEM diffraction), because there a very large range of angles present in the conical beam coming out of the specimen.Why two objective aperture images are visible when diffraction lens is not focusing on the back focal plane?Chapter 5.Aligning the detectorsOnce we have corrected the Ronchigram and the pivots, then all we have to do is get the detectors lined up with the beam coming out of the bottom of the specimen. In a TEM/STEM, the STEM detectors are usually mounted below the phosphor screen, and normally you can't actually see them. Quite often, because of space constraints, they are not mounted on the centre line of the microscope, but are off to one side.Ask the demonstrator: Please tell me roughly where the detectors are relative to the centre of the phosphor screen.There are normally two detectors. A solid-state circular disc is used to collect the bright-field signal. Around it is mounted another solid-state detector in the shape of a circular annulus, which is used to collect all the dark- field electrons: that is, all the electrons which have scattered to a large angle outside the cone of the Ronchigram. Looking down on the two detectors, they look like this:The STEM imaging will only work properly if we get three variables correctly adjusted: the camera-length (i.e. the effective distance or magnification between the specimen and the detector plane) and the x- and y-shift of the detector plane. It sounds simple, but there are a lot of things that can go wrong. This brings two questions. One is how to adjust the camera length and another is how to shift the detector plane? Anotherimportant issue is why the camera length is one critical factor which affects the STEM imaging.Suppose for a moment that the detectors are on the optic axis. What effect does changing the camera length have? Look at the next diagram.At very short camera-lengths (This means the image magnification is very low), the disc of the Ronchigram will be much smaller than the disc of the bright-field detector. This condition is good for dark-field imaging, because the annular detector is effectively lying at a high angle which is what we want for easy image interpretation. The image contrast is roughly proportional to the Rutherford scattering of electrons from the atomic nuclei. NOTE: ABOVE STATEMENT IS JUST SUITED TO THE ALLIGNMENT.As the camera length increases, the Ronchigram gets bigger and bigger, until it reaches a point where it covers the whole bright-field detector. In this condition, the signals on both the dark-field and bright-field detectors are at a maximum, although the contrast on both images will be rather poor.Why the disc of the Ronchigram much smaller than the disc of the BF detector is good for DF imaging?At even longer camera lengths, both the bright-field detector and the annular dark field detector are covered by the Ronchigram. In this condition, the bright-field image is very noisy and has low intensity, but it will have much more contrast and will be more like a conventional bright- field image in TEM mode.However, for any one camera length, think of all the things that can go wrong if the detector is not properly aligned, as shown in the next figure:Clearly, if the Ronchigram misses both detectors (which, by Sod's Law, is the most likely occurrence) then we will see nothing at all on the STEM monitors, because very few electrons will be hitting either of the detectors.If the detector is almost aligned correctly, the central disc of the Ronchigram will hit the dark-field detector, but miss the bright-field detector. Under these circumstances, the signal displayed on the so-called dark-field monitor will be bright, and will look like a bright-field image, because it is collecting all the electrons which have passed through the specimen. Even worse, the so-called bright-field detector will be detecting high-angle scattered dark-field electrons, and so it will look like a dark-field image. Because the annular dark-field detector is so much larger than the bright-field detector, there are many more ways to get this inversion of signals to occur than to get the signals the right way round. For this reason, people often spend many happy hours thinking the monitors on the STEM are the wrong way round.。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
扫描电子显微镜和透射电子显微镜分析摘要：电子显微镜是利用电子与物质作用所产生之讯号来鉴定微区域晶体结构，微细组织，化学成份，化学键结和电子分布情况的电子光学装置。
而常用的就是扫描电子显微镜以及透射电子显微镜。
而通过电子显微分析具有高分辨率等特点，故广泛的应用于化学、生物、医学、冶金、材料等领域等重要各个研究领域和工业部门。
关键词：扫描电子显微镜；透射电子显微镜；实例分析•扫描电子显微镜扫描电子显微镜不是通过电磁透镜放大成像的原理，而是以类似于电视摄像纤维方式，利用细聚焦电子束在样品表面扫描时激发出来的各种物理信号而来调制成像。
当高能的入射电子轰击物质表面时，被激发的区域将产生二次电子、俄歇电子、特征x射线和连续谱X射线、背散射电子、透射电子，以及在可见、紫外、红外光区域产生的电磁辐射。
同时，也可产生电子-空穴对、晶格振动（声子）、电子振荡（等离子体）。
原则上讲，利用电子和物质的相互作用，可以获取被测样品本身的各种物理、化学性质的信息，如形貌、组成、晶体结构、电子结构和内部电场或磁场等等。
由于电子枪的效率的不断提高，使扫描电子显微的样品室附近的空间增大，可以装入更多的探测器。
因此，目前扫描电子显微镜不只是分析形貌像，它可以和其他分析仪器组合，使人们能在同一台仪器进行形貌、微区成分和晶体结构等多种微观组织结构信息的同位分析。
•电子显微镜原理和主要结构扫描电子显微镜主要是通过背散射以及二次电子等物理信号成像，它工作是这样的：从电子枪灯丝中发出约为25~30μm的电子束，在受到了阳极的高压加速后，射向镜筒，经过光镜与物镜的聚焦之后，在样品表面形成一个具有一定能量、强度、斑点直径的电子束。
在扫描线圈的磁场作用下，入射电子束在样品表面上按照一定的空间和时间顺序做光栅式逐点扫描。
由于入射电子与样品之间的相互作用，将从样品中激发出二次电子。
由于控制镜筒入射电子束的扫描线圈的电路同时在控制显像管的电子束成像，用这样方式一点一线组成了像。
扫描电子显微镜是由电子光学系统，信号收集处理、图像显示和记录系统，真空系统三个基本部分组成。
扫描电子显微镜构造原理的方框图见图1-1。
1.1.1电子光学系统(镜筒)电子光学系统包括电子枪、电磁透镜、扫描线圈和样品室。
图1-1 扫描电子显微镜构造原理的方框图1.电子枪扫描电子显微镜中的电子枪与透射电子显微镜的电子枪相似，只是加速电压比透射电子显微镜低。
2．电磁透镜扫描电子显微镜中各电磁透镜都不作成像透镜用，而是作聚光镜用，它们的功能只是把电子枪的束斑(虚光源)逐级聚焦缩小，使原来直径约为50m m的束斑缩小成一个只有数个纳米的细小斑点。
3．扫描线圈扫描线圈的作用是使电子束偏转，并在样品表面作有规则的扫动，电子束在样品上的扫描动作和显像管上的扫描动作保持严格同步。
4.样品室样品台本身是一个复杂而精密的组件，它能夹持一定尺寸的样品，并能使样品作平移、倾斜和转动等运动，以利于对样品上每一特定位置进行各种分析。
新式扫描电子显微镜的样品室实际上是一个微型试验室，它带有多种附件，可使样品在样品台上加热、冷却和进行机械性能试验(如拉伸和疲劳)。
样品室内除放置样品外，还安置信号探测器。
1.1.2信号的收集和图像显示系统二次电子、背散射电子和透射电子的信号都可采用闪烁计数器来进行检测。
信号电子进入闪烁体后即引起电离，当离子和自由电子复合后就产生可见光。
可见光信号通过光导管送入光电倍增器，光信号放大，即又转化成电流信号输出，电流信号经视频放大器放大后就成为调制信号。
由于镜筒中的电子束和显像管中电子束是同步扫描的，而荧光屏上每一点的亮度是根据样品上被激发出来的信号强度来调制的，因此样品上各点的状态各不相同，所以接收到的信号也不相同，于是就可以在显像管上看到一幅反映试样生物各点状态的扫描电子显微图像。
1.1.3真空系统为保证扫描电子显微镜电子光学系统的正常工作，对镜筒内的真空度有一定的要求。
如果真空度不足，除样品被严重污染外，还会出现灯丝寿命下降，极间放电等问题。
1.2扫描电镜样品的制备对试样的要求试样可以是块状或粉末颗粒，在真空中能保持稳定。
1.含有水分的样品（多孔/镶样样品）应先烘干除去水分。
2.表面受到污染的试样，要在不破坏试样表面结构的前提下进行适当清洗，然后烘干。
3.新断开的断口或断面，一般不需要进行处理，以免破坏断口或表面的结构状态。
有些试样的表面、断口需要进行适当的侵蚀，才能暴露某些结构细节，则在侵蚀后应将表面或断口清洗干净，然后烘干。
4.对磁性试样要预先去磁，以免观察时电子束受到磁场的影响。
5.试样大小要适合仪器专用样品座的尺寸，不能过大，样品座尺寸各仪器不均相同，一般小的样品座为Φ 3 ～5mm，大的样品座为Φ 30 ～50mm，以分别用来放置不同大小的试样，样品的高度也有一定的限制，一般在5～10mm左右。
6.在对样品截面/侧面的观察时使用特殊的样品台，可以利用样品台的厚度，粘结在边上。
注意粘结的时候尽量降低样品的高度，否则不对喷金和观察。
7.在制备块状试样时，带污染的试样可在不影响样品的条件下进行超声波清洗，并烘干或吹干。
对于块状导电材料，除了大小要适合仪器样品座尺寸外，基本上不需要进行什么制备，用导电胶把试样粘结在样品座上，即可放在扫描电镜中观察。
对于块状的非导电或导电性较差的材料，要先进行镀膜处理，在材料表面形成一层导电膜。
以避免电荷积累，影响图象质量；并可防止试样的热损伤。
注意粘结的时候一定要牢，松动就会造成观察时的晃动，图像模糊。
1.3 扫描电镜应用以及实例分析采用SEM扫描电镜对结构陶瓷材料进行材料的微观组织形貌分析，可以对陶瓷材料的组织形貌对力学性能的影响进行分析。
并可以通过合适的工艺控制以得到理想的微观组织，以达到较高的力学性能。
对于硼化锆超高温陶瓷的组织形貌如下图所示。
图1-2硼化锆陶瓷的SEM照片可以从两张不同组分的结构陶瓷的微观结构可以看出其断口形貌具有显著的差别，在（b）中陶瓷的组织结构主要以等轴晶为主，而经过一定的成分和工艺优化之后，陶瓷材料的微观组织形貌逐渐向板状晶粒以及棒状晶粒过渡，从（c）中陶瓷的SEM照片中可以看出，陶瓷材料不再仅仅是单纯的等轴晶，而是由棒状晶和等轴晶组成，根据陶瓷材料中的晶粒的拔出，桥联以及裂纹偏转机制。
可以解释经过成分和工艺优化的试样（c）的强韧性大于（b）的试样。
图1-3硼化锆陶瓷的BSE照片从BSE照片中可以明显的看出陶瓷材料的相组成，由于陶瓷当中的组成两相的原子的序数的大小不同，可以根据电子扫描照片所产生的背散射电子的强度大小分析，材料当中的相的变化过程。
从图1-3陶瓷材料当中的背散射照片中可以看出，材料主要由三相组成，由深色的硼化锆相、稍微浅色的碳化锆，以及更浅色的金属相组成，并且其组织呈现出等轴晶粒，而通过一定的温度调整，可以看出材料中浅色的金属相逐渐的减少，而深色的硼化锆逐渐增加，说明可以通过背散射照片的观察材料当中的相组成，以及探究在原位合成过程中，材料的组组织以及相演变过程。
还可以通过背散射照片观察陶瓷材料的微裂纹扩展路径，分析陶瓷材料的断裂机制，判断裂纹断裂是通过晶间或晶内扩展，从而通过调整晶粒界面关系，实现陶瓷材料的增韧过程。
图1-4即为陶瓷材料的硬度压痕的微裂纹扩展过程，从图中可以看出，该陶瓷的断裂方式主要以晶间断裂为主，并且其中较多的棒状晶粒可以通过晶粒桥联以及晶粒拔出的机制，提高材料的韧性。
图1-4 硼化锆陶瓷的微裂纹扩展的BSE图像•透射电子显微镜透射电子显微镜(Transmission Electron Microscope,简称TEM),可以看到在光学显微镜下无法看清的小于0.2nm的细微结构，这些结构称为亚显微结构或超微结构。
要想看清这些结构，就必须选择波长更短的光源，以提高显微镜的分辨率。
1932年Ruska发明了以电子束为光源的透射电子显微镜，电子束的波长要比可见光和紫外光短得多，并且电子束的波长与发射电子束的电压平方根成反比，也就是说电压越高波长越短。
目前TEM的分辨力可达0.2nm。
2.1透射电子显微镜的结构组成透射电子显微镜包含有若干元件，其中有一个用于传输电子束的真空系统，用于产生电子束的电子发射源，一系列的电磁透镜，以及静电盘。
后两个器件允许操作者按照要求对电子束进行操作。
此外，还需要一个设备将样品移入或移出电子束通路，以及在通路中移动。
成像设备随后使用射出前述系统的电子束成像。
2.1.1电子枪电子枪由若干基本元件组成：灯丝，偏置电路，韦乃特阴极，还有阳极。
通过将灯丝和负电压电源相连，电子可以通过电子枪泵往阳极，并射入TEM的真空腔，从而完成整个回路。
电子枪用于使电子以一定的发散角度射出设备，这个角度被称为电子枪发散角，α。
通过放置充有比灯丝更多负电荷的韦乃特阴极，呈发散状射出灯丝的电子会在适当的操作下被转变为会聚的形式，其最小大小为电子枪的截面直径。
热电子发射电流强度，J，与发射电子材料的功函数和玻尔兹曼分布有关，关系如下，其中A是常数，Φ 是功函数，而T是材料的温度：这个等式表明，为了达到足够的电流强度，需要将灯丝小心加热，而多余的热量也不能将灯丝损坏，因此需要具有较高熔点的材料，如钨，或者可以选择其他功函数较低的材料，如六硼化镧作为灯丝的材料。
此外，六硼化镧和钨热电子源必须加热以使电子可以发射出来，通常可以使用一个小电阻片来达到这一目的。
为了防止热冲击，经常需要对电流进行延迟，以阻止热梯度对灯丝的损伤。
对六硼化镧材料，这个延迟通常长达数秒钟，而对于钨，这个延迟相对来说非常短。
2.2.2 电磁透镜电子透镜对电子束的作用类似于光学透镜对光线的作用，它可以将平行的电子束聚集在固定的焦点。
透镜可以使用静电效应，也可以使用磁效应。
TEM 中使用的电子透镜大多数都使用了电磁线圈以产生凸透镜的作用。
这些透镜产生的场必须是径向对称的，否则，磁场透镜将会产生散光等失真现象，同时会使球面像差与色差恶化。
电子透镜使用铁、铁钴合金或者镍钴合金、坡莫合金制成。
选择这些材料是由于它们拥有适当的磁特性，如磁饱和、磁滞、磁导等等。
电磁透镜的主要元件包括外壳、磁线圈、磁极、极靴以及外部控制电路组成。
极靴必须制造得非常对称，这样可以提供形成透镜磁场的合适的边界条件。
建像的失真。
透镜的空隙的大小、极靴的内径以及尖端的尺度，还有透镜的整体设计经常通过磁场有限元分析来完成，同时还需要考虑到设计的散热和电气限制。
产生透镜磁场的线圈位于透镜的外壳之内。
这些线圈中的电流可以变化，然而经常使用很高的电压，因此需要很强的绝缘能力，以防止透镜元件之间发生短路。
散热元件需要将由线圈电阻造成的发热散出。
线圈可能还需要使用水冷，亦即使用流动的冷水将热量带走。
2.2.3样品台TEM样品台的设计包括气闸以允许将样品夹具插入真空中而尽量不影响显微镜其它区域的气压。