The projection is against the view screen and two-dimensional relations in the z-axis between structures are lost. It is important that the or they will absorb too much of the electron beam samples need to be thin, The layout of the electron microscope: The main parts of the electron microscope: The (electron source) gun A wire is superheated by an electric current to emit electrons. The wire is usually tungsten or (LaB6). lanthanum hexaboride Electrons are collated into a and tight beam sent down the microscope column, across the sample, lenses, and apertures Lenses Electron lenses are that have been designed to magnetic coils focus and direct a passing electron are used to form and magnify an image: beam. Three primary lenses is the and does the The objective lens topmost lens first step of image magnification and focusing. The and its positioning and strength intermediate lens controls the magnification of the or the diffraction pattern. image The used to onto the imaging surface. projector lens focus and project the image The apertures Apertures are along the that can that holes microscope column limit the size of the electron beam passes through it. The first aperture, the is located It is used condenser aperture near the top of the column. to condense and maintain the coherence of the electron beam. The second aperture, the is located just after the objective aperture, below the sample objective lens. The objective aperture is used primarily to control contrast in the image coated with a material such as Fluorescent viewing screen or zinc sulfide
The projection is two-dimensional against the view screen and relations in the z-axis between structures are lost. It is important that the samples need to be thin, or they will absorb too much of the electron beam The layout of the electron microscope: The main parts of the electron microscope: The gun (electron source) A wire is superheated by an electric current to emit electrons. The wire is usually tungsten or lanthanum hexaboride (LaB6). Electrons are collated into a tight beam and sent down the microscope column, across the sample, lenses, and apertures Lenses Electron lenses are magnetic coils that have been designed to focus and direct a passing electron beam. Three primary lenses are used to form and magnify an image: The objective lens is the topmost lens and does the first step of image magnification and focusing. The intermediate lens and its positioning and strength controls the magnification of the image or the diffraction pattern. The projector lens used to focus and project the image onto the imaging surface. The apertures Apertures are holes along the microscope column that can limit the size of the electron beam that passes through it. The first aperture, the condenser aperture is located near the top of the column. It is used to condense and maintain the coherence of the electron beam. The second aperture, the objective aperture, is located below the sample just after the objective lens. The objective aperture is used primarily to control contrast in the image Fluorescent viewing screen coated with a or material such as zinc sulfide
Cell%20Biology%20Lab%20Manual.docx