Lecture 3: The Microscope

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Lecture 3 The Microscope
Questions Notes

• The History

• Hans and Zacharias Janssen of
• Holland in the 1590s created the
• first compound microscope

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• Anthony van Leeuwenhoek and Robert Hooke made
  improvements by working on the lenses

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II. How a Microscope Works
Convex Lenses are curved glass used to make
microscopes (and glasses etc.)
Convex Lenses bend light and focus it in one spot.
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How a Microscope Works
Ocular Lens (Magnifies Image)
Objective Lens (Gathers Light, Magnifies And
Focuses Image Inside Body Tube)
Body Tube (Image Focuses)

• Bending Light The objective (bottom) convex lens
  magnifies and focuses (bends) the image inside
  the body tube and the ocular convex (top) lens
  of a microscope magnifies it (again).

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• Light passes from a mirror or a light source to
  a specimen on a slide.

• The image is magnified by an objective lens.

• The image passes through the body tube to a
  second lens, the ocular or eyepiece.

• The image is magnified a second time by the
  eyepiece.

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III. The Parts of the Microscope

• Write about each part AND its function
• Draw each part

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Ocular Lens
Body Tube
Nose Piece
Arm
Objective Lenses
Stage
Stage Clips
Coarse Adj.
Diaphragm
Fine Adjustment
Light Source
Base
Skip to Magnification Section
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Body Tube

• The body tube holds the objective lenses and the
  ocular lens at the proper distance. The image
  focuses here.

Diagram
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Nose Piece

• The Nose Piece holds the objective lenses and can
  be turned to increase the magnification

Diagram
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Objective Lenses

• The Objective Lenses increase magnification
  (usually from 10x to 40x)

Diagram
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Stage Clips

• These 2 clips hold the slide/specimen in place on
  the stage.

Diagram
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Diaphragm

• The Diaphragm controls the amount of light on the
  slide/specimen

Turn to let more light in or to make dimmer.
Diagram
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Light Source

• Projects light upwards through the diaphragm, the
  specimen and the lenses
• Some have lights, others have mirrors where you
  must move the mirror to reflect light

Diagram
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Ocular Lens/Eyepiece

• Magnifies the specimen image

Diagram
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Arm

• Used to support the microscope when carried.
  Holds the body tube, nose piece and objective
  lenses

Diagram
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Stage

• Supports the slide/specimen

Diagram
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Coarse Adjustment Knob

• Moves the stage up and down (quickly) for
  focusing your image

Diagram
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Fine Adjustment Knob

• This knob moves the stage SLIGHTLY to sharpen the
  image

Diagram
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Base

• Supports the microscope

Diagram
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IV. Magnification
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Magnification

• To determine your magnificationyou just multiply
  the ocular lens by the objective lens
• Ocular 10x Objective 40x10 x 40 400

So the object is 400 times larger
Objective Lens have their magnification written
on them.
Ocular lenses usually magnifies by 10x
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V. Caring for a Microscope

• Clean only with a soft cloth/tissue
• Make sure its on a flat surface
• Dont bang it
• Carry it with 2 HANDSone on the arm and the
  other on the base

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Carry a Microscope Correctly
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VI. Using a Microscope

• Start on the lowest magnification
• Dont use the coarse adjustment knob on high
  magnificationyoull break the slide!!!
• Place slide on stage and lock clips
• Adjust light source (if its a mirrordont stand
  in front of it!)
• Use fine adjustment to focus

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Summary

• Write a 4-5 sentence summary of your notes. Be
  specific and detailed. Write in your OWN words
  and pick out the most important information.
• Study Questions Write 10 good study questions
  in the margin NEXT TO the answer. A good study
  question is one you think I might ask on the next
  test.