TEM构造、成像方式及变倍原理 1
1 TEM构造、成像方式及变倍原理
TEM构造、成像方式及变倍原理 ,TEM的照明、成像、观察记录、真空及电源系统 TEM的主要部件一样品台、光阑 TEM成像方式 Source-filament plus anode plates with Electron gun applied accelerating voltage. Vacuum Condenser Lenses-electromagnetic lenses column adjusted by lens currents not position. 。TEM变倍原理 Tilt rotation Specimen Stage-allows translations and tilts. Objective Lens-usually <50X. Imaging System-multiple electromagnetic lenses below the objective:set magnification, focal plane (image vs.diffraction pattern). Phosphor Detector/lmaging-fluorescent screen,plate screen:film: digital recording film,CCD camera. system Instruments often have attachments such as 1 in 1020 electrons X-ray detectors are collected 2
TEM的照明、成像、观察记录、真空及电源系统 TEM的主要部件—样品台、光阑 TEM成像方式 TEM变倍原理 2 TEM构造、成像方式及变倍原理
Structure of a TEM Example TEM schematic One of many types of TEMs Filament PHILIPS Wehnelt "Gun" Anode Gun deflectors 照明系统 Condensor aperture 1 8日 (may be adustable by user depending on TEM type) Condensor lens 1 Condensor stigmator Fixed aperture Condensor lens 2 Beam deflectors Condensor aperture 2 Sample holder Objective stigmator Objective lens upper Objective lens lower 样品室 Objective aperture Image deflectors Selected area aperture (or immediate aperture) Intermediate lens Diffraction stigmator 成像系统/ 11 Projector lens 1 Projector lens 2 图像观察 CCD camera Beam axis Viewing screen 3
3 Structure of a TEM 照明系统 成像系统/ 图像观察 样品室
照明系统 组成：电子枪、聚光镜和相应的平移对中、倾 斜调节装置组成 ·作用：提供一束高亮度、孔径半角小、平行度 好、束流稳定的电子波；通过聚光镜的控制可 以实现从平行照明到大会聚角的照明条件；为 满足中心暗场成像的需要，照明电子束可在 2~3°范围内倾斜 4
4 照明系统 • 组成：电子枪、聚光镜和相应的平移对中、倾 斜调节装置组成 • 作用：提供一束高亮度、孔径半角小、平行度 好、束流稳定的电子波；通过聚光镜的控制可 以实现从平行照明到大会聚角的照明条件；为 满足中心暗场成像的需要，照明电子束可在 2~3°范围内倾斜
照明系统 ·电子枪 1 CATHODE(negative potential) ·Thermionic(热电子) 2 WEHNELT Bias resistor ELECTRODE Tungsten (negative potential) LaB6 10-1000kV Space o Field emission(场发射) charge Electron Beam Crossover Cold FEG 3 ANODE PLATE Schottky FEG (positive potential) Ground Tungsten(W)hair-pin filament LaB.Tip Field-emission gun Tip 5
5 照明系统 Tungsten (W) hair-pin filament LaB6 Tip Field-emission gun Tip • 电子枪 • Thermionic (热电子) – Tungsten – LaB6 • Field emission (场发射) – Cold FEG – Schottky FEG