| Abstract: | The future of electron microscopy lies as much with the conventional as with the newer instruments. The point resolving power of the latter is likely to be pushed to 1 Å, but only after a considerable effort in solving problems of mechanical and electrical stability. Progress in correcting the lens aberrations is even slower. Techniques of specimen preparation and microscope operation are continuously being improved, but will need even greater refinement if proper use is to be made of a 1 Å resolving power, e.g. for identifying bases in a nucleic acid molecule. Extension of the working voltage to 1 MeV and above is increasing the usefulness of the conventional electron microscope, particularly in metallurgy, and plans are now being made for even higher voltages. Of the newer, unconventional instruments, the scanning electron microscope is already establishing a place for itself, especially in industrial applications where surface conditions on the microscale are important. It is likely to find increasing use in micro-circuitry, but also in some branches of biological research, even if its resolving power cannot be brought below 100 Å. The combination of X-ray spectrometry with electron microscopy holds promise of wide application, in the form of a hybrid electron microscope-microanalyser. Secondary-emission microscopes are slowly finding a place for themselves, mainly in applied science and technology. Mirror microscopes, for surface investigations, and ion microscopes, for microanalysis, are still in an early stage but have interesting possibilities. The field ion microscope, simplest in principle but sophisticated in technique, is unique in showing the position of individual atoms in a metal tip. It is already finding applications, especially in studies of radiation damage. |
