Abbe Darkfield Condensers

This tutorial explores how a changes in the size of the opaque stop in a simple Abbe darkfield illumination condenser affects light cone shape and numerical aperture.

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To operate the tutorial, move the slider to effect a change in the size of the opaque stop. The default size is a stop that produces a numerical aperture of 0.4, intended for use with a 10x objective. As the size of the opaque stop is changed, the numerical aperture of the hollow light cone also changes to produce a new light cone of different numerical aperture. The condenser numerical aperture is given for each light cone along with the suggested objective magnification.

Contributing Authors

Mortimer Abramowitz - Olympus America, Inc., Two Corporate Center Drive., Melville, New York, 11747.

Matthew J. Parry-Hill and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.