Microscopy

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Microscopy

• Light and Electron Microscopy

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The First Light Microscopes

• Around 1590 Zaccharias and Hans Janssen
  experimented with lenses in a tube, leading to
  the forerunner of the microscope and the
  telescope
• In the late 1600s, Anton van Leeuwenhoek was the
  first to see bacteria, yeast, and many other
  microbes using a microscope

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How Light Microscopes Work

• First, the objective lens gathers light from the
  specimen and magnifies the image
• Most microscopes have several objective lenses
  that can be rotated into position to provide
  different levels of magnification (4X, 10X, 40X)
• The ocular lens in the eyepiece magnifies and
  transmits the image to your eye
• The magnification of the ocular lens is 10X
• To find the total magnification of the microscope
  you are using, multiply the magnification of the
  objective lens by the magnification of the ocular
  lens.
• For example 40X (objective lense) x 10X (ocular
  lense) 400X magnification

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The Parts of a Light Microscope

• Light source Could be a mirror, but most likely
  it is a bulb built into the base
• Diaphragm Adjusts the amount of light striking
  an object
• Objective lens Gathers light and magnifies image
• Ocular lens (eyepiece) Magnifies objects and
  focuses light to your eye
• Stage Holds slide
• Can be moved using the coarse or fine adjustment
  knobs to bring the object into focus
• Stage clips Hold slide in place
• Base and arm Structural support for the
  microscope

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Can you name the parts?Start on the left side
and work from the top down. Then go to the right
side and work from the top down.
Ocular lens (eyepiece)
Arm
Objective Lenses
Stage clip
Stage
Course adjustment
Diaphragm
Fine adjustment
Light Source
Base

• Nice Job !

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Images Produced by Light Microscopes
Amoeba
Streptococcus bacteria
Anthrax bacteria
Plant cells
Human cheek cells
Yeast cells
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Beyond Light Microscopes

• Light microscopes are limited by their
  resolution.
• Light microscopes cannot produce clear images of
  objects smaller than 0.2 micrometers
• The electron microscope was invented in the
  1930s by Max Knott and Ernst Ruska
• Electron microscopes use beams of electrons,
  rather than light, to produce images
• Electron microscopes can view objects as small as
  the diameter of an atom

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Types of Electron Microscopes

• Transmission electron microscopes (TEMs) pass a
  beam of electron through a thin specimen
• Scanning electron microscopes (SEMs) scan a beam
  of electrons over the surface of a specimen
• Specimens from electron microscopy must be
  preserved and dehydrated, so living cells cannot
  be viewed

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Images Produced by Electron Microscopes
Cyanobacteria (TEM)
Lactobacillus (SEM)
Campylobacter (SEM)
Deinococcus (SEM)
Avian influenza virus
House ant
Yeast
Human eyelash
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Using Microscopes to Visualize the Three Shapes
of Bacteria

• Cocci (round)
• Bacilli (rod)
• Spirilla (spiral)
• Light microscope

Three shapes of bacteria taken with an SEM
Spirilla
Bacilli
Cocci
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References

• http//education.denniskunkel.com/catalog/product_
  info.php?products_id1123
• http//micro.magnet.fsu.edu/
• http//inventors.about.com/library/inventors/blrob
  erthooke.htm