Electron Microscope

electron microscope electron microscopes are scientific instruments that use the beam of highly energetic electrons to examine objects on a very fine scale the electron microscope gives information about the topography morphology composition and crystallographic nature of any object electron microscopes were developed to overcome the limitations of light microscopes the electron microscopes are of two types namely transmission electron microscope TEM and scanning electron microscope SEM Max Noll and Ernst Ruska of Germany designed the transmission electron microscope in 1931 working of an electron microscope electron microscopes function exactly as their optical counterparts except that they use a beam of electrons instead of light to view the specimen and gain information about its structure and Composition electron microscope consists of an electron source and magnetic lenses condenser lens objective lens and projector lens are magnetic lenses the magnetic lens is formed by passing suitable steady current through a coil of wire enclosed in an EIN shield the magnetic lenses help to control the path of the electrons there is a viewing port and also a fluorescent screen the basic steps involved in the working of all electron microscopes can be understood with the help of this schematic representation the electrons emitted from the hot filament of the electron source are accelerated by high potentials the condenser magnetic lens concentrates these electrons the object to be viewed is placed on a special holder the concentrated beam of electrons is made to strike the object to be viewed the electrons get partially absorbed by the object the object of lens placed below the object forms an enlarged image of the object this magnified image serves as a virtual object for the projector lens the magnetic projector lens produces the final enlarged image of the object on a fluorescent screen for visual examination or on a photographic plate for permanent record the whole system is placed in an evacuated chamber so that the electrons are able to move freely from the filament to the screen electrons source all electron microscopes generally use a thermionic gun as a source of electrons a Fermi on a gum is shown here a positive electric potential is applied to the anode plate the filament which is the cathode is heated until a stream of electrons is produced the electrons are then accelerated by the positive potential down the column

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Keywords: What is a Electron Microscope, Electron Microscope, Electron Microscopes, What is an Electron Microscope, Used Electron Microscope, Electron Microscope Definition, Define Electron Microscope

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Length: 4min 28sec (268 seconds)

Published: Tue Mar 19 2013