This tutorial explores how light is scattered and diffracted by a specimen into the front lens of a darkfield reflected light objective. Instructions for use of the tutorial appear below the applet window.

	Interactive Java Tutorial
ATTENTION Our servers have detected that your web browser does not have the Java Virtual Machine installed or it is not functioning properly. Please install this software in order to view our interactive Java tutorials. Visitors using the Netscape and Microsoft Internet Explorer browsers can download the appropriate software from the websites where the browsers are distributed. Please do not contact us for information about specific URLs where this software can be obtained.

Use the slider to translate the specimen into and out of the hollow cone of illumination produced by the objective. Light enters the hollow periphery of the objective (which serves as a condenser in this situation) and is reflected through a series of lenses and mirrored surfaces. The focused light is then projected into an apex that illuminates the specimen at an oblique angle from every azimuth. No zeroth order light reaches the specimen, only light that has been diffracted, refracted and reflected from the surface of the specimen is able to enter the front lens of the objective to form an image. In the absence of a specimen, the viewfield appears totally back, because no light is reflected or diffracted into the objective.