Light & Electron Microscopes

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  • Created by: Lilly
  • Created on: 06-01-13 21:43

Light Microscopes

  • They use light and a system of lenses to magnify images of small samples .

Advantages

  • Image is shown in colour
  • Cheaper than electron microscopes
  • Smaller, easier to use
  • The samples is alive

Disadvantages

  • Lower reolution than electron microscopes
  • An additional lamp is needed

 

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Electron Microscopes

  • Use elrctrons instead of light to form an image.

Advantages:

  • Clearer resolution-more detail
  • No additional lamp is needed
  • Greater depth of field

Disadvantaes:

  • Mor expensive than light microscopes
  • Big, so harder to use

 

 

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Scanning Electron Microscope (SEMs)

  • Scan a beam of electrons across the specimen
  • Knocks off electrons from specimen, which are gathered in a cathode ray tube, which forms an image.

Advantages

  • Can be used on thick specimens
  • Produces a 3D image

Disadvantage

  • Expensive
  • Large
  • Must be kept in an area with minimal electricm magnetic or vibration interference
  • Lower resolution than TEMs
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Transmission electron microscope (TEMs)

  • Uses electromagnets to focus beams of electrons, dense areas of specimen absorb more electrons

Advantages

  • Higher Resolution than SEMs
  • Small objects can be seen clear
  • Wavelength of electrons shorter
  • Powerful magnification- greater detail

Disadvantages

  • Can only be used on thin specimens
  • All water has to be removed in a vaccum, so the cell must be dead
  • Black & white image produced
  • Potential artifacts from extensive sample preparation
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Comments

mariah

thaaannk yoooouuu!!!!

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