THE MICROSCOPE A Valuable Biological Tool

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THE MICROSCOPE - A Valuable Biological Tool

• w. d. johnson

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Items to Be Covered During Microscope Lab

• What is a microscope?
• What are the parts of a light compound
  microscope?
• How do you use a microscope?
• How do you make a wet mount slide?
• What are some characteristics of microscopic
  viewing?
• What is a dissecting microscope?

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What Is a Microscope?

• Name derived from Greek words micro
  meaning small and scope to see
• Used to see details invisible to the naked eye
• A valuable tool for the biologist
• Research in cell biology
• Medical diagnosis and tests
• Observation of microbes - the oldest and most
  numerous life form on earth

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What Is a Microscope?

• Light compound microscope
• Transmitted light passes through a specimen on a
  glass slide, through two or more magnifying glass
  lenses, and appears as an enlarged image at the
  eyepiece

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What Are the Major Parts of a Light Compound
Microscope?

• Eyepiece (ocular) lens - magnifies image
• Body tube directs light through scope
• Nosepiece contains objective lenses and
  switches from high to low power
• Arm handle to carry microscope
• Stage platform used to mount microscope slide

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What Are the Major Parts of the Light Compound
Microscope?

• Eyepiece lens
• Body tube
• Coarse adjustment
• Fine adjustment
• Revolving nosepiece
• Objective lenses
• Stage
• Iris diaphragm lever
• Base

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What Are the Major Parts of a Light Compound
Microscope?

• Stage adjustment knobs moves slide across stage
  to view different areas of specimen
• Objective lenses high low power, magnifies
  image
• Iris diaphragm controls light intensity
• Coarse adjustment knob rough focusing
• Fine adjustment knob fine focusing

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How do you use a microscope?-rules for
microscope use

• Always use two hands for carrying microscope
• Lens paper only for cleaning lenses
• Always use low power first
• Fine focus only when using high power
• Return scope to assigned cubicle with low power
  in place, cord neatly wrapped, and dust cover on.

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How do you use a microscope?-focusing hints

• Turn revolving nosepiece to low power
• Place slide with coverslip on stage and center
  specimen
• Use coarse adjustment to raise stage all the way
  up
• Turn fine adjustment one turn upward

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How do you use a microscope?-focusing hints
(cont.)

• Look into eyepiece and lower stage with coarse
  adjustment until specimen comes into view
• Adjust light intensity with iris diaphragm lever
• Use fine adjustment for sharp focusing
• For high power viewing, follow above steps and
  then rotate nosepiece to high power objective.
  Use fine focus only!

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How Do You Make a Wet Mount Slide?

• Get a clean glass slide and coverslip
• Obtain a specimen that is thin enough to allow
  light to shine through it
• Place small drop of water or stain solution in
  center of slide
• Mount specimen on drop and slowly lower coverslip
  at an angle over specimen so it floats on top

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What Are Some Characteristics of Microscope
Viewing?

• Magnification
• The power of magnification is marked on each
  lens. For example ocular 10x, low power 4x,
  high power 43x
• The total magnification is determined by
  multiplying the power of the ocular lens times
  the power of a single objective lens. For
  example under low power (10x)(4x) 40x.
  Therefore, your object appears 40 times greater
  than natural size.

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What Are Some Characteristics of Microscope
Viewing?

• Orientation of image
• The lenses of the light compound microscope cause
  the image to be reversed so your viewing is
  upside down and backwards from the actual
  specimen on the slide.
• Note when you move your slide to the right, your
  image moves to the left when you move your slide
  down, the image moves upward.

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What Are Some Characteristics of Microscope
Viewing?
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What is a Dissecting Microscope?

• The dissecting scope or stereoscopic microscope
  is a binocular (two eyepiece) scope used to view
  and easily manipulate thicker, larger specimens.
• Specimen is seen magnified in 3D and in natural
  position.

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Dissecting Scope Vs. Light Compound Scope
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Vocabulary Review

• Magnification enlargement of image
• Resolution clarity of image
• Transmitted light light that passes through
  specimen
• Reflected light light that bounces off of
  specimen

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Vocabulary Review

• Parfocal objective lenses have the same
  focusing distance
• Depth of field area or depth of sharp focus
• Field of view circular area seen through
  microscope
• Binocular two eyepieces allowing 3D view

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The End