Abstract :
An introduction to the electron microscope is given. Starting from the limitations to the resolving power of the optical microscope, the discovery of de Broglie concerning the wave aspect of moving particles and the derivation of the electron lens by Busch are described. The limiting action of the spherical aberration of the electron lens is discussed and the theoretical resolving limit set by this and diffraction effects is evaluated as 10 ¿ngstrom units (¿). A very brief historical outline of early work is given. The functions and requirements of the various parts of a practical instrument are discussed and a description is given of the new instrument designed by the author and his collaborators. The description includes details of the mechanical construction of the tube and its accessories, as well as general notes on the vacuum system, circuits and operation of the instrument. Finally, a few examples of results obtained on the instrument are given.
