Abbe Condenser Chromatic Aberrations
Abbe and aplanatic substage condensers are uncorrected for chromatic aberration, and even if they are properly adjusted using Köhler illumination, an undesirable color effect will be present in photomicrographs made using these condensers. This tutorial demonstrates color fringes that occur at the field diaphragm edges as a result of chromatic aberration in Abbe condensers.
To operate the tutorial, use the slider or the blue arrow buttons to simulate translation of the condenser up and down the optical axis of the microscope. This action mimics what happens when the condenser rack is adjusted. When the condenser is at the highest point in the rack (tutorial initialization default), the edges of the field diaphragm blades will have a reddish-yellow color fringe on the perphery. As the slider is moved to the right (simulating a downward movement of the condenser), the fringe around the diaphragm blades transitions in color to red and then blue. The optimum height for the Abbe condenser is that where the color fringes surrounding the field diaphragm blades are red on the interior and blue on the exterior.