This tutorial explores how focus can be varied on thick samples to selectively bring different focal planes into view. Optical sectioning is a technique that is possible with contrast enhancing techniques such as Hoffman modulation contrast.

	Interactive Java Tutorial
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The tutorial simulates optical section using Hoffman modulation contrast optics combined with other contrast enhancing techniques such as polarized light and darkfield illumination. To operate the tutorial, first select a specimen from the pull-down menu. Next, use the Focus Depth slider to move through different focal planes of the specimen.