《材料分析测试技术》课程PPT教学课件（讲稿）第五章 透射电镜的结构

第五章通电镜的结构 光学显微镜的发明为人类认识微观世界提供了 重要的工具。随着科学技术的发展,光学显微 镜因其有限的分辨本领而难以满足许多微观分 析的需求。上世纪30年代后,电子显微镜的发 明将分辨本领提高到纳米量级,同时也将显微 镜的功能由单一的形貌观察扩展到集形貌观察、 晶体结构、成分分析等于一体。人类认识微观 世界的能力从此有了长足的发展

第五章 透射电镜的结构 光学显微镜的发明为人类认识微观世界提供了 重要的工具。随着科学技术的发展，光学显微 镜因其有限的分辨本领而难以满足许多微观分 析的需求。上世纪30年代后，电子显微镜的发 明将分辨本领提高到纳米量级，同时也将显微 镜的功能由单一的形貌观察扩展到集形貌观察、 晶体结构、成分分析等于一体。人类认识微观 世界的能力从此有了长足的发展

Definitions Microscope-a device with a lens or series of lenses that enlarge(magnify) the appearance of an object Does not apply to sem Image- Perception of an object using your eyes (vision). One can sense an object without vision (touch, etc . ). Requires visible light Lens -A lens is an optical component which is used to focus beams of radiation Lenses for light are usually made of a glassy material, whereas non-uniform electromagnetic fields are used as lens for electrons

Definitions Microscope - A device with a lens or series of lenses that enlarge (magnify) the appearance of an object. Does not apply to SEM. Lens - A lens is an optical component which is used to focus beams of radiation. Lenses for light are usually made of a glassy material, whereas non-uniform electromagnetic fields are used as lens for electrons. Image - Perception of an object using your eyes (vision). One can sense an object without vision (touch, etc..). Requires visible light

eases Curved glass or mirror for concave convex Concave surface of metal(e.g. satellite dish Radio waves Concave mirror or fresnel lens Heat Rotational Axis Solenoid(electromagnetic fields that Electron Beam can be varied) Subatomic particles(electrons protons, positrons Solenoid Windin Symmetrical Asymmetrical

Lenses Curved glass or mirror for Visible light Concave surface of metal (e.g. satellite dish) Radio waves Concave mirror or Fresnel lens Heat Solenoid (electromagnetic fields that can be varied) Subatomic particles (electrons, protons, positrons) concave convex

Magnification- The ratio between image size to the object size. Can be varied by changing the distance between the object and the final lens (of the eye)or by inserting a second lens between the two DvesStaine OJOLYSCIENCES Imunehemteals CUSTOM SYNTHESIS/CUSTOM PACKAGING Resolution- The point at which two or more objects can be distinguished as separate

Resolution - The point at which two or more objects can be distinguished as separate. Magnification - The ratio between image size to the object size. Can be varied by changing the distance between the object and the final lens (of the eye) or by inserting a second lens between the two

History. First record of using glass lens for magnification was by an Arabian from what is now known as Iran, Alhazen, in the 10 and 11th century He contradicted ptolemy's and euclids theory of vision that objects are seen by rays of light emanating from the eyes; according to him the rays originate in the object of vision and not in the eye Because of his extensive research on vision, he has been considered by many as the father of modern optics

History: First record of using glass lens for magnification was by an Arabian from what is now known as Iran, Alhazen, in the 10 and 11th century. He contradicted Ptolemy's and Euclid's theory of vision that objects are seen by rays of light emanating from the eyes; according to him the rays originate in the object of vision and not in the eye. Because of his extensive research on vision, he has been considered by many as the father of modern optics

15th century on- Studies done with glass magnifiers to study objects in detail mostly as a curiosity by non- scientists- Antonie van Leeuwenhoek(linen draper) described three shapes of bacterial cells using his simple single lens microscope(glass bead in metal holder)

15th century on - Studies done with glass magnifiers to study objects in detail mostly as a curiosity by non￾scientists - Antonie van Leeuwenhoek (linen draper) described three shapes of bacterial cells using his simple, single lens microscope (glass bead in metal holder)

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By mid-19th century became evident that theoretical lmts of lght were reached Above magnification of 1500, resolution lost. Image was larger, but blurred(empty magnification) In 1870, Ernst Abbe derived mathematical expression for resolution of microscope Resolution is limited to approx. 1/2 the wavelength of illuminating source

By mid-19th century, became evident that theoretical limits of light were reached. Above magnification of 1500, resolution lost. Image was larger, but blurred (empty magnification). In 1870, Ernst Abbe derived mathematical expression for resolution of microscope: Resolution is limited to approx. 1/2 the wavelength of illuminating source

Wavelength-distances! between peaks of the waveform THE ELECTROMAGNETIC SPECTRUM 10110210310410510610710810910 Size of a niger Water Molecule Bates writs name of wave HARD X RAYS MICROWAVES soEX我AY5 CAMMA RAYS ⊥上 ,心 People ght Bb (waves per second) 10610310810910101011101210131014101510161017101810191020 Energy of one electron volts)1091081071061051041031021011103102103104105106

Wavelength - distance between peaks of the waveform