illuminating aperture stop

The aperture stop that controls the angle of sample illumination, and thus resolution and depth of field. It is located in a conjugate aperture plane in the illumination optics.

Synonyms: illuminating aperture diaphragm

See also: Köhler illumination, conjugate planes, optical train, aperture stop, stop

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Conjugate Planes in Optical Microscopy

Image-forming and aperture planes form two independent focal sets in the optical train.