Microscopy

Microscopy

Magnification & Resolution
1. Magnification is how much bigger it appears under the microscope than it is in real life
  1. MAGNIFICATION = IMAGE SIZE + ACTUAL SIZE
2. The term resolution refers to the ability to see two distinct points separately
The light microscope
1. Light passes from a bulb under the stage...
  1. ...through a condenser lens...
    1. ...and then through the specimen
      1. This beam of light is passed through an objective lens and then the eyepiece lens
2. OVERALL MAGNIFICATION = OBJECTIVE LENS MAGNIFICATION x EYEPIECE LENS MAGNIFICATION
  1. Some specimens have to be prepared before being viewed under the telescope
    1. 1. STAINING: coloured stains are chemicals that bind to chemicals in the specimen that allow the specimen to be seen
    2. 2. SECTIONING: specimens are embedded in wax - thin sections are then cut out without distorting the specimen
The Electron Microscope
1. Higher resolution
  1. Generate a beam of electrons that can distinguish objects at 0.2 nm apart
2. TRANSMISSION ELECTRON MICROSCOPE
  1. Electron beams pass through a very thin prepared sample and electrons pass through denser parts less easily
3. SCANNING ELECTRON MICROSCOPE
  1. The electron beam is directed onto a sample. The electrons do not pass through the specimen, they bounce off

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