microscopes

• • light microscopes use light and have a lower resolution than EM max resolution of 0.2 micrometres
  • used to look at whole cells or tissues
  • max useful magnification is x1500
• • laser scanning confocal microscopes use laser beams to scan a specimen which is tagged with a florescent dye
  • laser causes dye to give of light which is focused through a pinhole onto a detector which generates an image (3d)
  • see objects at different depths in thick specimens
• Electron microscopes use a beam of electrons to create a highly detailed image of the specimen.
• TEM- use electromagnets to focus a beam of electrons. which is transmitted through the specimen, denser parts absorb more

  provide high resolution images but can only be used in thin specimens
• SEM- scan a beam of electrons across the specimen, this knocks off electrons from the specimen which are gathered in a cathode ray tube to make an image

  show surface of specimen, can be 3D

  lower resolution then TEMs