Histology — The Light Microscope

Light microscopes come in many varieties but they all have the same basic components.  Here is an image of a light microscope with its parts labeled…  (click on it for a larger image)

02.01.02 Microscope with labels

Here is a detailed list with descriptions of the function of each part…

  1. Eyepiece: The eyepiece functions as the last lens that light passes through before you see it.  Most eyepieces also contain a pointer and/or a reticle.
    1. The pointer functions to point out specific things that are being viewed (an instructor or student may place the pointer on a specific cell so that another person can see exactly which cell is being looked at or asked about).
    2. The reticle appears as a small ruler with lines and numbers (the units of the reticle depend on the magnification being used).
  2. Arm: The arm of the microscope functions as a very stable connection between the viewing parts of the microscope with the base and stage of the microscope.  The arm, along with the base, are also used to carry the microscope
  3. Mechanical stage: The mechanical stage has knobs at the side of the stage that are used to move the slide being viewed in two dimensions  (up-down and left-right) as viewed through the microscope.  Attached to the mechanical stage are the stage clips.  These clips hold the slide firmly in place.
  4. Course focus adjustment knob: This is the larger of the two focus knobs.  When the course focus knob is turned it brings the objective lens and the specimen closer together or farther apart, helping to focus the image.  This knob should only need to be used when first bringing the specimen into focus under the smallest objective lens…  at higher magnification this knob moves the focus to fast.
  5. Fine focus adjustment knob: This is a smaller knob that moves the objective lens and specimen more slowly in order to nudge focus smaller amounts and perfect the focus.
  6. Condenser: The condenser is a lens below the stage through which light passes before it moves through the specimen.  The condenser can be adjusted with an adjustment knob.  Once a specimen is in focus the condenser can be adjusted to improve the view.
  7. Base: The base gives a stable platform for the entire microscope.
  8. Light source: The light source enough light to see the specimen well.
  9. On/off/dimmer switch: This switch allows us to turn the light source on and off, and also allows us to adjust the level of light being sent through.
  10. Diaphragm adjustment lever: This lever is used to adjust the amount of light passing through the diaphragm.
  11. Stage: The stage gives a stable platform for the specimen to be viewed.
  12. Objective lenses: The objective lenses magnify the image (along with the eyepiece).  Most light microscopes have three or four objective lenses in order to view specimens at different levels of magnification.
  13. Rotating nosepiece: This device allows us to move from one magnification (one objective lense) to another.

 

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