Light Microscopy

Optical microscopes use lenses to bend light and magnify images (extent of magnification determined by lenses)

  • Most light microscopes include both an ocular lens (~10×) and objective lens (~10×; 40×; 100×)

Components of a Light Microscope




       Focus Mechanism

       Revolving Nosepiece

       Objective Lenses


       Stage Clips

       Iris Diaphragm

Function of Microscope Components:

  • Eyepiece – The point through which the magnified image is observed (contains ocular lens)
  • Focus Mechanism – Responsible for resolving the image (may include both fine and coarse focus adjustments)
  • Revolving Nosepiece – Rotating device that allows for selection of objective lens
  • Objective Lens – Magnifies image of specimen (in conjunction with ocular lens)
  • Stage – Platform on which specimen is positioned (specimen is usually affixed to a glass slide) 
  • Stage Clips – Holds specimen in place (some mechanical stages can be moved to reposition slide while viewing)
  • Iris Diaphragm – Regulates the intensity of light that is projected onto the slide
  • Light Source – Either external (redirected by mirrors) or internal (light bulb within the microscope base)