KOHLER ILLUMINATION

Published in Microbiology
Tuesday, 25 July 2017 13:43
What is Kohler illumination?

Kohler illumination is a method of adjusting a microscope in order to provide optimal illumination by focusing the light on the specimen. When a microscope is in Kohler, specimens will appear clearer, and in more detail.

Process of setting Kohler
 
Materials required
 
  • Specimen slide (will need tofocus under 10× power)
  • Compound microscope.
 
Kohler illumination
 
  1. Mount the specimen slide onthe stage and focus under 10×.
  2. Close the iris diaphragm completely.
  3. If the ball of light is not in the center, use the condenser centering screws to move it so that it is centered.
  4. Using the condenser adjustment knobs, raise or lower the condenser until the edges of the field becomes sharp (see Figure 797.1 and Figure 797.2).
  5. Open the iris diaphragm until the entire field is illuminated.
 
Note the blurry edges of the unfocused light
Figure 797.1 Note the blurry edges of the unfocused light
 
Adjusting the condenser height sharpens the edges of the ball of light
Figure 797.2 Adjusting the condenser height sharpens the edges of the “ball of light.”
 
When should you set/check Kohler?
 
  • During regular microscope maintenance
  • After the microscope is moved/transported
  • Whenever you suspect objects do not appear as sharp as they could be.
 
Further Reading:
 

Useful Sites

  • NCBI

    National Center for Biotechnology Information
  • LTO

    Lab Tests Online® by AACC
  • ASCP

    American Society for Clinical Pathology
  • ASM

    American Society for Microbiology
  • The Medical Library®

    Project of BioScience.pk
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