Fluorescence microscope

From ArticleWorld

The fluorescence microscope is a type of microscope used in the study of organic and inorganic substances. These microscopes are very important as they have opened up the field of biology as they were the prototype to more advance designs such as the confocal laser scanning microscope.

This microscope uses technology relating to the phenomena of fluorescence and phosphorescence rather than reflection and absorption. This technology uses high-energy, short wavelength light to excite the electrons in the particular molecules inside the sample. These electrons are shifted to a higher orbit and when they fall back to their original orbits release energy which is of a longer wavelength.

Epi-fluorescence

The most common type of fluorescence microscope used is the epi-fluorescence microscope. The principle followed here is one of an optical set-up of a fluorescence microscope. Here the objective lens is used both to focus and collect the fluorescent light from the specimen. This method is more efficient than the use of transmitted fluorescence which uses different lens to focus the light on the specimen.

Mechanics of fluorescence microscope

This method uses a microscope that has a mercury or xenon lamp to produce the required ultra violet light. The light enters the microscope and hits a dichroic mirror. This mirror reflects only one range of wavelengths and allows the other to pass through. This causes the light to be reflected up to the specimen where it excites fluorescence in molecules. The objective lens then collects the wavelength of fluorescent light produced and this passes through the dichroic mirror and a barrier filter where the image is formed in the eyepiece. The molecules that emit this fluorescent light can be naturally this way or may require exposure to a dye that induces this reaction.