Microscopes

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Microscopes

  1. 1. Microscopy: The Science of the Microscope
  2. 2. The Invention of the Microscope • Renaissance invention (Mid 1600s) • Credit for invention goes to Anton Van Leeuenhoek • Constructed simple curved glass lenses in combination
  3. 3. Improving the Microscope • Robert Hooke • English biologist who discovered cells • Increased magnification with improved lenses
  4. 4. Modern Compound Light Microscopes • Uses 2 lenses in combination to magnify an image • Can view objects too small to be seen with unaided eye • Object must be thin enough for light to pass through • Can view living things • Typical magnification 100x to 1000x See page 17 of your packet for a detailed discussion of: • Parts and their functions • Proper use and handling • Procedures for making a wet mount
  5. 5. Pushing the Limits: Electron Microscopes • A light microscope cannot be used to distinguish objects that are smaller than half the wavelength of light • Any object with a diameter smaller than 0.275 micrometers will be invisible or, at best, show up as a blur • Electrons are speeded up in a vacuum until their wavelength is extremely short, only one hundred-thousandth that of white light. • Electron microscopes were developed in the 1930s
  6. 6. Electron Microscopes • Uses a beam of electron to view the specimen (not light) • Specimen viewed must be prepared in a vacuum (no air molecules) therefore living things cannot be viewed using this type of scope • Magnifies up to 200,000x magnification
  7. 7. Scanning Electron Microscope
  8. 8. Scanning Electron Microscope or SEM • Bounces electrons off the surface of the object • Produces a 3 dimensional image of the object
  9. 9. Red Blood Cells
  10. 10. Blood Clot
  11. 11. Nerve Cells
  12. 12. Tongue with a Taste Bud
  13. 13. Sperm on Surface of Human Egg
  14. 14. The Split End of a Human Hair
  15. 15. Tooth Plaque
  16. 16. Transmission Electron Microscope
  17. 17. Transmission Electron Microscope • Electrons pass through the object forming a one dimensional picture • Allows one to view the inside of an object (ex. internal structure of a cell)
  18. 18. filamentous bacteria from the gut of a termite
  19. 19. Sperm heads from a stick insect
  20. 20. Salmonella Bacteria
  21. 21. Stereoscope • Allows viewing of macroscopic objects with great detail • Does not require light to pass through object • Can view living things • Typical magnification of 10X to 30X
  22. 22. Choosing the Correct Microscope
  23. 23. Microscope Lab Skills Review Complete the microscope review activities on pages 41 and 43-44.

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