The microscope is a vital instrument in a great variety of scientific and technical work, and is used by many who have otherwise no considerable acquaintance with optical instruments (Martin 1966). It is also defined as a device used for examining small objects and tiny living organisms like bacteria, fungi, protozoa, algae and virus which cannot be seen with the eye (Carpenter 1977).
Today both light and electron microscopes are used extensively in microbiology research. Prokaryotic cells, nucleoids, large organelles of eukaryotic cells are seen by the use of light microscope. Using electron microscope objects which are small as the single protein molecules are seen. Microscopes are very important to microbiologists interested in the structure of living organisms. A good microscope provides both increased magnification (increases the apparent size of an object) and resolution (increase the clarity of the image). The ability of microscopes to make small details visible depends on the wavelength of the illumination used to view the object. The smaller the wavelength, the smaller the details that can be seen. The best light microscopes, using the shortest light waves in the blue range (wavelength about 450 nanometers), can reveal objects in the specimen as small as 0.2 micrometer.