... of electron microscopes. The Transmission Electron microscope (TEM) and the Scanning Electron Microscope (SEM). In the TEM the electrons are directed onto the object, but some of the electrons are absorbed by the object so they do not reach the screen setting a dark image (electron dense). The specimen has to be cut very thin, so usually it is no more than 500nm thick. A fluorescent screen is placed under it so it can sample the magnified image. It can be capable of magnifying an object up to 1 million times. The second type (SEM) creates a magnified image of the surface of the abject. In a SEM, a tightly focused electron beam moves over the sample. As it scans over the object, an image of the object is displayed on the monitor. The SEM has a magnifying power of over 100,000. SEM's produce a detailed image of the surface of ...

See this essay or coursework document in full right now