电子显微镜（electron microscope）.doc

电子显微镜（electron microscope） Electron microscopes are commonly used for transmission electron microscopy (transmissionelectronmicroscope, TEM) and scanning electron microscopy (scanningelectronmicroscope, SEM). Compared with the light microscope, the electron microscope replaces the visible light with an electron beam and replaces the optical lens with an electromagnetic lens, and uses the fluorescent screen to image the invisible electron beam of the naked eye. Compared with the light microscope, the electron microscope replaces the visible light with an electron beam and replaces the optical lens with an electromagnetic lens, and uses the fluorescent screen to image the invisible electron beam of the naked eye. Electron microscope (hereinafter referred to as electron microscopy) is an instrument based on the principle of electron optics, which uses electron beams and electron lenses instead of beams and optical lenses to make fine structures of matter to be imaged at very high magnification. The electron microscope consists of three parts: a lens barrel, a vacuum device and a power cabinet. The lens barrel mainly consists of an electronic source, an electronic lens, a sample holder, a phosphor screen and a detector. These parts are usually assembled from top to bottom into a cylinder. An electronic lens used to focus electrons is the most important part of an electron microscope barrel. Magnetic lenses are commonly used, and sometimes electrostatic lenses are used. The space electric field or magnetic field with a symmetry to the cylinder axis of the electron trajectory to the axis of bending forming focus, optical lens and its role in optical microscope (convex lens) the beam focusing effect is the same, so called electron lens. The focal point of the optical lens is fixed, and the focal point of the electronic lens can be adjusted, so the electron microscope does not have a movable lens system like that of the optical microscope. Most modern electronic microscopes