Posted by Fred Koenig on Nov 18th 2020

Compound Microscope Parts, Functions, and Labeled Diagram

Parts of a Compound Microscope

Each part of the compound microscope serves its own unique function, with each being important to the function of the scope as a whole. The individual parts of a compound microscope can vary heavily depending on the configuration & applications that the scope is being used for. Common compound microscope parts include:

Labeled Parts of a Compound Microscope

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Compound Microscope Definitions for Labels

  • Eyepiece (ocular lens) with or without Pointer: The part that is looked through at the top of the compound microscope. Eyepieces typically have a magnification between 5x & 30x.
  • Monocular or Binocular Head: Structural support that holds & connects the eyepieces to the objective lenses.
  • Arm: Supports the microscope head and attaches it to the base.
  • Nosepiece: Holds the objective lenses & attaches them to the microscope head. This part rotates to change which objective lens is active.
  • Base: Bottom base of the microscope that houses the illumination & supports the compound microscope.
  • Objective lenses: There are usually 3-5 optical lens objectives on a compound microscope each with different magnification levels. 4x, 10x, 40x, and 100x are the most common magnifying powers used for the objectives. The total magnification of a compound microscope is calculated by multiplying the objective lens magnification by the eyepiece magnification level. So, a compound microscope with a 10x eyepiece magnification looking through the 40x objective lens has a total magnification of 400x (10 x 40).
  • Specimen or slide: The object used to hold the specimen in place along with slide covers for viewing. Most slides & slide covers are thin glass rectangles.
  • Stage or Platform: The platform upon which the specimen or slide are placed. The height of the mechanical stage is adjustable on most compound microscopes.
  • Stage clips or mechanical stage: Clips on the stage that hold the slide in place on the mechanical stage.
  • Aperture - Disc or Iris Diaphragm: Circular opening in the stage where the illumination from the base of the compound microscope reaches the platform of the stage.
  • Abbe Condenser: This lens condenses the light from the base illumination and focuses it onto the stage. This piece of the compound microscope sits below the stage & typically acts as a structural support that connects the stage to arm or frame of the microscope.
  • Coarse and fine adjustment controls: Adjusts the focus of the microscope. These knobs increase or decrease the level of detail seen when looking at the slide or specimen through the eyepiece of the compound microscope.
  • Stage height adjustment: Adjusts the position of the mechanical stage vertically & horizontally. It is important to adjust these knobs so that the objective lens is never coming into contact with the slide or specimen on the stage.
  • Mirror: Reflects light into the base of the microscope. Earlier microscopes used mirrors that reflected light into the base of the microscope instead of halogen bulbs as their source of illumination.
  • Illumination: Light used to illuminate the slide or specimen from the base of the microscope. Low voltage halogen bulbs are the most commonly used source of illumination for compound microscopes.
  • Bottom Lens or Field Diaphragm: Knob used to adjust the amount of light that reaches the specimen or slide from the base illumination.

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