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Electron Microscopes. Use electrons instead of light to form images. Light Microscopes. Light Microscopes. Unknown when first invented, but probably between 1590-1610 A.D. Can magnify up to 1000 x
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Electron Microscopes Use electrons instead of light to form images.
Light Microscopes • Unknown when first invented, but probably between 1590-1610 A.D. • Can magnify up to 1000 x • Shines light through an object and projects the image through a series of lenses that magnify the image. • Relatively inexpensive
Uses • Great for studying live microscopic organisms. • Great for studying cells and tissues in general. • Widely used in hospitals and clinics to diagnose disease.
Transmission Electron Microscope(TEM) • First invented in 1931 (in Germany) • Can magnify up to 200,000 x (and beyond) • Similar to a light microscope except that a beam of electrons is used instead of light. The electrons that penetrate through the object and create an image which is then enlarged and then viewed on a computer monitor. • Samples of the object must be sliced very thin before using the TEM. (No living specimens.) • Very expensive and time consuming to prepare slides.
Uses of the TEM • Used in biological/medical research to investigate parts of cells and molecules. • Used in material science to study the structure and the weaknesses of crystals. • Used in nanotechnology.
Example images using TEMs Nanotubes
Example images using TEMs Marburg virus
Scanning Electron Microscope(SEM) • http://www.mos.org/sln/SEM/
Scanning Electron Microscope(SEM) • First invented in 1942 • Can magnify typically up to 10,000 x • Gives a 3D image of the surface of the object • Again, a beam of electrons is used instead of light. The electrons that bounce off the object create the image. The microscope scans a certain region of the object multiple times and then combines multiple images to create what we then see on a computer monitor as one 3D image. • No slicing needed so easier to prepare samples. Larger objects can be viewed. • Very expensive.
Uses of the SEM • Multiple uses - for viewing the surface of any microscopic object. • Insect parts • Bacteria • Food industry • Material science • Education • Art
Example images using SEMs • Mascara brush
Example images using SEMs • Moth antennae
Practice Quiz • Now look at the following images. Determine which type of microscope produced each image and write your answers down on a piece of paper. • LM = Light Microscope • TEM = Transmission Electron Microscope • SEM = Scanning Electron Microscope
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