Concentric alignment of the condenser phase plate slits with the phase ring, positioned inside the objective, is of paramount importance in phase contrast microscopy. This tutorial explores the effect of phase plate/ring alignment on specimen contrast using this important microscopy technique.

	Interactive Java Tutorial
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Each time the tutorial is first downloaded or subsequently reloaded, a new set of alignment parameters is automatically initialized by the applet. To operate the tutorial, first adjust the specimen Focus and Intensity sliders to achieve the best possible image. Next, use the Phase Ring Position X and Y sliders to maximize specimen contrast. The Phase Telescope radio buttons will allow the visitor to toggle between viewing alignment of the phase ring/plate and the field view of the specimen. To ensure proper phase ring/plate alignment, first toggle the Phase Telescope radio button to the In position and use the sliders to align the plate outline within the phase ring. Then toggle the Phase Telescope out of the light path to view the specimen under optimum conditions of phase contrast illumination. The Reset button allows the visitor to randomly reset the applet.