Microscopes

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Microscopes
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History of the microscope

• The first compound microscope was created in the
  1590s.
• Anthony van Leeuwenhoek and Robert Hooke made
  improvements by working on the lenses

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Robert Hooke

• Discovered the cell
• Hooke coined the term cell for describing
  biological organisms.
• He examined very thin slices of cork and saw a
  multitude of tiny pores that he remarked looked
  like the walled compartments of a honeycomb.

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The compound light microscope

• Has two sets of lenses and allows light to pass
  through a specimen to form an image.
• It can produce clear images of objects at a
  magnification of 1000 times.
• Must have two characteristic to be useful
• Magnification
• Resolution

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Magnification

• Magnification is the enlarging of the image so it
  can be seen easier

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Field of view
Middle power

• The area you see through the microscope.
• The field of view gets smaller as you go from
  scanning power to high power. This is why you
  find the image under the lowest power first.
• Always center the object before you change to a
  higher power.

High Power
Lowest power (scanning lens)
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Resolution
good resolution
poor resolution

• Resolution is the ability to distinguish between
  two points. Clear images are easier to see than
  blurry images.

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Resolution
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Parts of a microscope
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Parts functions

• Optical parts of the compound light microscope
• 1. Ocular lens/eye piece
• Contains a magnifying lens, usually 10x or 15x.
  To look through.

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Parts functions

• 2. Objective lens has three different
  magnifying lenses.
• On our microscopes
• A. Scanning lens magnifies image 4X
• B. Low power magnifies 10X
• C. High power magnifies 40X

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Total magnification

• How is total magnification of the microscope
  determine?
• Multiply the magnification of the eye piece lens
  by the magnification of the objective lens.
• For example if the eye piece is 10X and you use
  the low power objective lens which is also 10X,
  your total magnification is 100X.

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Parts functions

• 3. light source
• 4. diaphragm regulates amount of light that
  passes up towards the eye piece.
• 5. Base support microscope
• 6. Arm supports body tube
• 7. Stage supports slide to be observed.

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Parts functions

• 8. Body tube keeps proper distance between eye
  piece and objectives.
• 9. Nosepiece hold objectives, can be rotated.
• 10. Course Adjustment moves body tube in order
  to focus the image.
• 11. Fine Adjustment moves body tube slightly to
  sharpen image.

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Bacteria
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Blood cells
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How to make a wet-mount slide

• 1. Get a clean slide and cover slip
• 2. Place one drop of water in the middle of the
  slide.
• 3. Place the edge of the cover slip on one side
  of the water drop.
• 4. Slowly lower to cover slip on top of the drop
• 5. Place the slide on the stage and first view
  with the scanning lens.

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