What Is a Fluorescent Microscope?

A fluorescent microscope is a device used to examine the amount and type of fluorescence emitted by a sample. Unlike a conventional microscope, a fluorescent microscope creates readable images through the use of irradiation and filtration, rather than traditional reflection. This type of microscope is a vital tool in cellular and genetic research, including in the production of three-dimensional images of microbes.

Fluorescence is a phenomenon that occurs when a material becomes excited, or more active, by exposure to radiation. As the material begins to calm down, the energy created by the excitement is emitted as light. In some substances, fluorescence is a naturally occurring property, meaning no external irradiation is necessary to cause the emission of light. Other substances are not naturally fluorescent, but can become so when excited by the correct wavelength of light. A fluorescent microscope is the primary means for exciting and observing such materials.

In a fluorescent microscope, a sample can be hit with light specifically selected to create fluorescence. Using a filter, the microscope allows only the chosen wavelength to reach the sample, in order to ensure the best reaction. The light source used to create fluorescence may vary, depending on the type of fluorescent microscope and sample. One of the most common light sources used in fluorescent microscopy is a mercury vapor lamp, which creates an extremely bright light. Another frequently used type of light is the xenon arc lamp, which produce a light similar to daylight. In some situations, lasers, rather than traditional lights, may be used instead.

Once the sample has been excited, a second filter becomes necessary to block out the initial wavelength of light. Known as a beam-splitter, this filter reflects light at a lower wavelength than that used to excite the sample. This means that the image created in the microscope will not be contaminated by the initial light source, as the higher wavelength light will pass through the beam-splitter. Thus, the final image created will reflect only the fluorescent light from the sample itself.

The fluorescent microscope has many different applications throughout the scientific world. Most often, it is used in the study of cells and micro-organisms, since it can pinpoint specific details in tiny samples with a high degree of accuracy and clarity. Medical and biological researchers frequently use fluorescent microscopy to study DNA and RNA, learn about the behavior and structural details of cells, and study antibodies to better understand disease.