Fluorescence microscope
From Wikipedia, the free encyclopedia
A Fluorescence Microscope is a light microscope used to study properties of organic or inorganic substances using the phenomena of fluorescence and phosphorescence instead of, or in addition to, reflection and absorption.
In most cases, a component of interest in the specimen is specifically labeled with a fluorescent molecule called a fluorophore (such as GFP, Green fluorescent protein). The specimen is illuminated with light of a specific wavelength (or wavelengths) which is absorbed by the fluorophores, causing them to emit longer wavelengths of light (of a different color than the absorbed light). The illumination light is separated from the much weaker emitted fluorescence through the use of an emission filter. Typical components of a fluorescence microscope are the light source (Xenon or Mercury arc-discharge lamp), the excitation filter, the dichroic mirror (or dichromatic beamsplitter), and the emission filter (see figure below). The filters and the dichroic are chosen to match the spectral excitation and emission characteristics of the fluorophore used to label the specimen.
Most fluorescence microscopes in use are epi-fluorescence microscopes (ie : excitation and observation of the fluorescence are from above (epi) the specimen). These microscopes have become an important part in the field of biology, opening the doors for more advanced microscope designs, such as the confocal laser scanning microscope and the total internal reflection fluorescence microscope (TIRF).
Fluorophores lose their ability to fluoresce as they are illuminated in a process called photo-bleaching. Special care must be taken to prevent photobleaching through the use of chemicals or by minimizing illumination.
[edit] See also
[edit] References
- Bradbury, S. and Evennett, P., Fluorescence microscopy., Contrast Techniques in Light Microscopy., BIOS Scientific Publishers, Ltd., Oxford, United Kingdom (1996).
- Rost, F. and Oldfield, R., Fluorescence microscopy., Photography with a Microscope, Cambridge University Press, Cambridge, United Kingdom (2000).
