A fluorescence microscope is similar to a conventional light microscope with some added features to enhance its capabilities. It uses a higher intensity light source, which may be a mercury or xenon lamp, to produce ultraviolet light.
When UV light enters a fluorescence microscope, it reflects on a dichroic mirror, which is a type of mirror that reflects some wavelengths and allows other wavelengths to pass through. This mirror bounces the light waves onto the specimen being examined, exciting the fluorescent molecules within the specimen. The fluorescent-wavelength light is gathered by the objective lens. The light waves pass through the dichroic mirror, and the barrier filter removes all light except that emitted from the sample. The light then goes to the eyepiece to produce the image.