Electron Microscopes - Essay Example

But, unlike the ordinary microscopes, the electron microscope uses a ray of electrons (Miller and Levine, 2003) which is shorter in wavelength, traveling through a vacuum, and focused by magnets to very thin objects whose sizes needs to be magnified. Also, the electron microscopes can only magnify specimens that have been properly killed, processed, and mounted for viewing (Engelkirk and Burton, 2007). There are two types of electron microscopes. These are the transmission electron microscope (Figure 1) and the scanning electron microscope (Figure 2).

The transmission electron microscope allows the viewer to see the internal parts of a microorganism at 1 million times size magnification (Figure 3). On the other hand, the scanning electron microscope allows the viewer to see the external surface parts of a microorganism at approximately 20 nano meter resolution (Figure 4). These two types of electron microscopes have each a built-in camera that can take pictures of images under study. So, besides visibility reasons, specimens are usually stained for more accurate observations, but the micrographs or pictures are black and white (Engelkirk and Burton, 2007.

The basic parts of. nsmission electron microscope are high voltage electrical supply line, electron gun, first condenser lens, condenser aperture, second condenser lens, specimen holder, with air-lock, objective lenses and aperture, and fluorescent screen with camera (Figure 5). On the other hand, the basic parts of scanning electron microscope are Control console, electron guns, thermo ionic electron gun, field ionic gun, thermal field emitters, Schottky emitter, and vacuum system: vacuum pumps, roughing pump/mechanical pump, diffusion pump, turbo pump, ion pump (CEMS) (Chemical Engineering and Material Science, 2003).

Biologist use transmission microscope to emit a ray of electrons from side to side of a thin sample that has to be examined for its internal structure. In contrast, biologist use scanning electron microscope to emit a fiber-thin electron ray across the surface of the sample producing a clear picture of the surface structure (Miller and Levine, 2003).Conclusion Electron microscopes are biomedical laboratory instruments that enable biologist to accurately configure the internal and external structure of microorganism which were considered in the past as invisible organisms.

Photo by: Ernst Ruska. 1980, BerlinFigure 1: Transmission electron microscope Source: Epner Technology Inc. ISO 9001. 2000,NADCAPFigure 2: Scanning electron microscope Title: General Cytology; Publisher: W.B. Saunders; Publication Date: 1960Figure 3: The transmission electron microscope allows the viewer to see the internal parts of a microorganism at 1 million times size magnificationTitle: General Cytology; Publisher: W. B. Saunders; Publication Date: 1960 Figure 4: Scanning electron microscope allows the viewer to see the external surface parts of a