Microscopy

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Microscopy
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Microscopy
Microscope

• an instrument that gives an enlarged image of the
  object under study
• Compound microscope
• Electron microscope
• Scanning probe microscope

• the study of objects or organisms (e.g.,
  bacteria, protists, cells, etc.) too small to be
  seen by the naked eye using a tool called a
  microscope

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Type of microscope Magnification Generated image Key features How it works
Optical compound microscope Up to 1 000x Magnified color view Samples on glass slides are sometimes stained Visible light and lenses produce a magnified image of an object
Scanning electron microscope Up to 50 000x Sharp 3D black and white image Surface structures of a sample Thin beam of electrons scanned across the surface of the sample reflected electrons make up image
Transmission electron microscope Up to 10 000 000x Sharp 2D black and white image Details inside cells and nanoparticles (1 micrometer thick samples) Beam of electrons passed through sample, image is magnified, focused by a lens and captured by a computer
Scanning probe microscope Up to 90 000 000x 3D black and white computer image of atoms on surface of sample Looks at individual atoms A probe with a tip only an atom wide scans across a samples surface
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Compound light microscope

• Magnification
• Enlargement of the image of the specimen
• Total magnification objective lens
  magnification ocular lens magnification
• Resolution
• ability to see a gap separating two dots in an
  image that, to the naked eye, are not separated.
• Influenced by frequency of light waves and
  quality of the lens
• Contrast
• Condenser and diaphragm modify size and intensity
  of a light beam

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Using the microscope

• Carrying the microscope properly
• Mounting the slide
• Viewing the specimen
• images are backward and inverted
• FOV gets darker as magnification increases
• Preparing the microscope for storage

Illuminating the field of view Brighter Darker
Mirror Correct angle, concave side Wrong angle, plane side
Iris diaphragm Fully open Partially closed
Objective Lower magnification Higher magnification
Condenser Closer to stage Farther from stage
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Preparing samples for viewing

• Staining cells for better visibility
• Place several drops of stain on one edge of the
  cover slip
• The process of diffusion will allow the stain to
  go under the cover slip and stain the specimen
• (tissue paper may be placed on the opposite edge
  of the cover slip to help the stain diffuse under
  the cover slip)

http//www.biosci.ohio-state.edu,
http//www.doctortee.com/dsu/tiftickjian/bio100/ce
ll-lab.html
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Microscope Math

• Theoretical magnification
• ocular X objective
• Estimating the diameter of the field of view
• (LPO diam)(LPO mag) (HPO diam)(HPO mag)
• Estimating cell size
• diameter / of cells spanning the diameter

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