Micron Optics - Nikon Microscope Systems for New Jersey and Puerto Rico
Koehler Illumination Steps
1. Focus on the sample with the 10x objective.
Image focused at 10x. Because the condenser is not yet aligned, the image is a little fuzzy.
2. Close the Field Diaphragm. This is typically on the base of the microscope below the stage. Sometimes it is a knob located on the right side of the microscope (E800, E1000)
3. Focus the image of the field diaphragm to a sharp octagon using the condenser focus knob found on the left side of the microscope directly behind the condenser. The condenser is lens unit located directly below the stage.
Image of field diaphragm is focused but not centered
4. Center the image of the field diaphragm using the silver knurled condenser centering knobs located at 8 o'clock and 4 o'clock directly below the condenser.
Image of field diaphragm is focused and centered
5 Open the image of the field diaphragm until it just disappears from view with the 10x objective. (Note: you will need to open it all the way if you are using objectives lower than 10x.
Properly adjusted image
6. Adjust the image for optimum contrast (most pleasing to your eye) using the condenser diaphragm. The control for the condenser diaphragm is located on the front of the condenser itself. (It is located on the right side of the stand near the back on the E800M and E1000M)
In this example the aperture is stopped down too far, and the image has very high contrast and appears "grainy". There is a inverse relationship between contrast and resolution.
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Micron Optics, 240 Cedar Knolls Road , Cedar Knolls, NJ 07927