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Dark Field Microscope

In this set up a special condenser is used to focus a hollow core of light onto the specimen which is illuminated at an oblique angle so as to prevent any light rays penetrating the specimen from entering the objective lens.

In this way, the microscopic field ought to appear dark if no specimen is placed on the slide. In the presence of a specimen to be examined, various structural features begin to scatter light, some of which are dispersed at angles that permit such rays to enter the objective lens.

This enables the formation of the image of the specimen which shines bright against a dark background. This situation is opposite to that of bright field microscopy where specimens are observed by transmitted illumination.

Dark field microscopy comes in handy for observing those microorganisms that are not stained easily by usual staining procedures.