Conjugate Planes

This tutorial explores how conjugate planes are in common focus when a microscope of finite tube length is adjusted for proper Köhler illumination.

To operate this tutorial, use the sliders to shift the focus of the conjugate planes in the illumination light rays (left slider) and/or the image-forming light rays (right slider). You will notice that as the sliders are moved, all images (either the filament or the specimen) drift in and out of focus together.