Fluorescence Microscopy (FM) is an important microscopic technique for biological, biomedical and materials sciences. Fluorescence is the property of some molecules and atoms to absorb light at a particular wavelength (excitation) and then emit light at a longer wavelength (emission). Current fluorescent microscopes combine state of the art optical systems with computerized control and the capability to obtain digital images. For biological and biomedical applications, materials can be labeled with fluorescently labeled probes and visualized under the fluorescent microscope.
One difference of FM to standard light microscopy is that higher intensity light is used to illuminate the sample. The light is passed through a filter prior to reaching the sample; this filter only passes wavelengths that excite the fluorescent molecules of interest. The second filter passes only those wavelengths at are emitted when the sample fluoresces. There are several important applications of FM. Examples are: 1) Use of fluorescent dyes: fluorescent dyes are taken up by cells and concentrated in specific cellular locations for visualization, 2) Protein tagging: cells are modified so that they create their own fluorescing molecules. This approach can be used to study the locations of the proteins within the cells or study the proteins as they move through the cells, 3) Immunofluorescence: this involves the use of antibodies to which fluorescent markers have been attached. These fluorescent antibodies bind specifically to target molecules on the surface of cells.