General chemistry

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BIOL2010LModule1A1.ppt
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Module 1 The Microscope

Dr. Glenn F. Gebler

Why do we use a microscope?

  • Many things are smaller than we can see with the naked eye. To accurately study Biology we need a tool to help us see these tiny things.

Types of Microscopes

  • Binocular scopes allow you to see in 3D.

  • Binocular Compound Microscope
  • A compound microscope is one that has two lens, usually one in the eyepiece and another that can be varied.
  • These have a magnification of up to 1000X.
  • We use binocular scopes in our lab.

Types of Microscope – Our Lab Uses Nikon E200

Microscope Handling

  • Getting the microscope out.
  • Always carry the microscope with two hands, holding it close to your body.

Microscope Handling

  • Putting the microscope away.
  • Clean stage if it is oily, and use lens paper to clean lenses.

  • Shortest objective lens (the one with the red band) should be pointing down toward stage.

  • Use course focus to position stage as low as it can go.

  • Always put scope back in numbered parking spot in scope cabinet.

  • The microscope should always be stored with the 4X (red) lens in place and the stage in its lowest position.

Microscope Handling

What Is a Compound Microscope?

  • Compound = two major lenses
  • Oculars – the set closest to your eyes (A).
  • Objectives – the set nearest to the object (B).
  • Please refer to Module 1A notes for an interactive quiz in microscope parts and function.

A.

B.

Microscope Parts – Under the Stage

Stage clip

Stage adjustment knobs

Backwards and forwards

Side to side

Microscope Parts – Under the Stage

[

Iris Diaphram

]

Condenser Lens

Total Magnification

  • When the image travels through the objective lens and the ocular lens it magnifies the magnification of the objective lens by 10X.
Ocular lens Objective lens Total magnification
10X Red 4X 40X
10X Blue 10X 100X
10X Yellow 40X 400X
10X White 100X 1000X

Magnification

  • The number of TIMES an objects apparent size is INCREASED by the lens system.
  • The total magnification of the lens system is determined by MULTIPLYING the power of the objective times the power of the eyepiece (usually 10x).

*

Resolution

  • The ability of the lens system to distinguish and SEPARATE fine details in a specimen.

Resolution

Resolution = Sharpness

Field of view

  • The AREA of the specimen which is seen through the lens system. The bright circle you see when looking into a microscope.

Magnification and Field of View

  • As magnification increases, we are zooming in on the specimen
  • This causes field of view to decrease
  • So you see less area but with greater detail.

Depth of field

  • The ability of a lens system to furnish a distinct image ABOVE and BELOW the focal plane. Depth of focus decreases with the increase of magnification.

Working Distance Between Lens and Slide

  • Use only the fine focus knob with the 40X and 100X lens.
  • As working distance decreases, magnification increases.

As Magnification Increases

  • All of these factors decrease

  • field of view
  • depth of field
  • working distance
  • amount of light
  • But resolution increase (at 100x resolution will decrease unless oil is used)

Parfocal

  • When the objective is in focus, it can be SWITCHED from one power to another, with only small fine focus adjustments being necessary.

Focusing an Image

  • Place the slide on the stage, held in place by the stage clip.

  • ALWAYS start with the 4X lens. Focus your image.
  • Move to the 10X lens, focus.

  • NEVER use the coarse focus higher than 4X.
  • Repeat at the 40X lens, focus using the fine focus.

The Oil Immersion Lens

  • The oil immersion lens or 100X lens is used with special optical oil. It makes the image clear at a higher magnification
  • Your instructor will tell you if you need to use this lens.
  • It is important to remove all the oil if you use the oil immersion lens.

The Oil Immersion Lens

The high magnification lens is very small. The light coming through the specimen may bend in air so much that it misses the small high-magnification lens.

Immersion oil is used to keep light from bending.

Cleaning the Oil Immersion Lens

  • Please use only lens paper to clean the lenses, never paper towels or Kimwipes.

  • Never use dry lens paper to clean eyepieces. Use the cleaning solution provided or breathe on the surface to be cleaned, then wipe.

Microscope Troubleshooting: The image is upside down and/or backwards

  • Is the slide right-up? The microscope will have a hard time focusing on an upside down microscope.

Microscope Troubleshooting: Everything is Dark

  • Is the microscope plugged in?
  • Is the power switch on?
  • Is the objective lens snapped into position
  • Is the light control set correctly
  • If you are using the 100X objective, did you remember to add a drop of immersion oil?

Microscope Troubleshooting: I Can’t Find Anything on Low Power!

  • Using the stage controls, make sure to center the microscope slide directly under the objective lens.
  • Focus up and down with the coarse focus knob.

Microscope Troubleshooting: When I Move to a Higher Power, Everything Disappears

  • Return to the previous (lower) power objective and relocate the cell of interest.
  • Only use fine focus when you return to the higher power objective.

Microscope Troubleshooting: The Image is Blurry

  • Clean the microscope ocular lens with lens paper
  • If the image is blurry on all powers, then clean the slide. It probably has too much oil on it.