Electron microscopes

• • electron microscopes use a beam of electrons instead of light rays
• Depth of field


  the distance between the nearest and farthest objects in focus
• The scanning electron microscope (SEM)

  • has a large depth of field
  • can be used to examine the surface structure of specimens
  • often used at lower magnifications
• The transmission electron microscope (TEM)

  • used to examine thin slices or sections of cells or tissues
  • have a maximum magnification of around x1000000
  • images can be enlarged beyond that photographically
  • the limit of resolution of the TEM is now less than 1 nm
  • has revealed structures in cells that are not visible with the light microscope