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    • CommentAuthorjuruble
    • CommentTimeJul 11th 2007 edited

    This protocol explains how to: center the condenser on the Olympus fluorescent microscope (Kohler illumination).

    Protocol revised: 6/27/2007

    Protocol written by: Barbara Lom, Fiona Watson, Julie Ruble


    NOTE: While following this protocol, please reference the labeled diagram found below.  A full-sized version of this image is available here.

    1. Focus on a slide with the 10X or 20X objective.  
    2. Ensure that everything is out of the path of the condenser and that the condenser aperture and field aperture are open.  Ensure that the eyepieces are set to 0 magnification.
    3. Turn up light to middle power (~10).
    4. Close field aperture down until the light appears as a small polygon through the eyepieces.
    5. Adjust the height of the stage (using the stage height knobs; see below) to sharpen the point of light. It should have sharp sides and corners.
    6. Use the centration knobs to center the point of light.
    7. When the point of light seems sharp and centered, open the field aperture up while looking through the eyepieces until the circle of light almost fills the entire view, but you can see each point of the polygon.  You can make sure that each point touches the outside border of your circular field of view; this tells you that your light is, indeed, centered. 
    8. You can now open the field aperture beyond field of view to use the microscope.




    • CommentAuthorjuruble
    • CommentTimeMar 27th 2008

    Make sure you're well-focused on your slide in step 1 or you will be unable to sharpen your polygon of light in steps 4 and 5. 

    • CommentAuthorsapyfrom
    • CommentTimeNov 16th 2010
    Note that if you are taking images at multiple magnifications, that you should repeat this procedure for every objective that you use.
    • CommentAuthorvibeamer
    • CommentTimeSep 30th 2011
    If every part of the microscope has been aligned, and there still seems to be a shadow or the image looks like a phase ring is blocking the light, focusing the condenser should alleviate this problem.
    • CommentAuthoralfleming
    • CommentTimeDec 14th 2011
    1. Turn on the microscope and apply low amount of light to the stage.
    2. Place your slide onto the stage and try to move it into the correct position where you think you will view your specimen.
    3. Focus on the slide using the coarse and fine focus knobs with whichever objective you intend to use to view your slide. If you have to change objectives you will need to "reKohler" the microscope.
    4. Rotate the field aperture counter-clockwise until it is just barely open.
    5. Make sure the phase ring selector is on bright field and not on one of the phase rings.
    6. Use the concentration knobs to find an octagon and attempt to place it as close to the center of the view able area as possible.
    7. Create a well defined octagon using the stage height knobs.
    8. Adjust the field aperture controls by rotating it clockwise trying to inscribe the octagon inside the view able circle. Use the concentration knobs to move the octagon around so the octagon is inscribed and as close to centered as possible.
    9. Continue to rotate the field aperture clockwise so the light completely (but just barely) covers the entire view able area.
    10. Remove the non-focusing eyepiece (usually the right) and look through that eyepiece only.
    11. There should be another octagon and using the condenser aperture control, fill roughly three quarters of the view able area with the light.
    12. Place the non-focusing eyepiece back in and you are ready to use the microscope.