Advantage and disadvantage of using an optical and electron microscope.

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ADVANTAGE AND DISADVANTAGE OF USING AN OPTICAL AND ELECTRON MICROSCOPE

In this essay I will be talking about all the different types of Optical and Electron Microscopes and what there uses are and what the Advantage and Disadvantage of them both are.

Electron Microscope

An electron microscope uses electrons to illuminate an object. Because electrons have a smaller wavelength than light has it can resolve much smaller structures than light can. The resolution is very good. The minimum wavelength of an optical microscope is 500nm whereas the smallest wavelength of electrons in an electron microscope is round about 0.005nm.

The microscope has many different features. It has an electron gun so that it can emit electrons onto the specimen so it can create a magnified image. Magnetic lenses that create the magnetic fields are used to direct and focus the electrons onto the specimen. The microscope uses a vacuum system because electrons are easily scattered by air molecules  so the microscope has a high vacuum. The can also produce images that the electrons have made.

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There are two types 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 ...

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