. The electron microscope, its development, present performance and future possibilities. Electron microscopes. Possibilities of Future Development 111 potential lens is connected with the cathode as usual, whereas the outer electrode, preferably earthed, is formed pole pieces of the magnetic lens. The object is placed outside this lens, shielded from the strong electrostatic fields by an apertured diaphragm. The focal length of this first lens is supposed to be of the same order as in present-day microscopes, , about cm for 60 kev Fig. 40. Potential and trajectories
. The electron microscope, its development, present performance and future possibilities. Electron microscopes. Possibilities of Future Development 111 potential lens is connected with the cathode as usual, whereas the outer electrode, preferably earthed, is formed pole pieces of the magnetic lens. The object is placed outside this lens, shielded from the strong electrostatic fields by an apertured diaphragm. The focal length of this first lens is supposed to be of the same order as in present-day microscopes, , about cm for 60 kev Fig. 40. Potential and trajectories in electrostatic lenses The space charge lens is essentially a cylindrical magnetron, but with the important difference that it contains no axial cathode. Its main parts are a long coil, which produces, at least in the middle part, a nearly homogeneous magnetic field, a tubular anode or sheath electrode *'A," and a cathode "C," which is a filament, bent to a coaxial circle. The currents are. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gabor, Dennis, 1900-. Brooklyn, Chemical Pub. Co.
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