ABSTRACT
The electron emerged from obscurity in 1897 and it took just 30 years for it to acquire an “optics”: in 1927, Hans Busch demonstrated that the motion of beams of electrons travelling in the vicinity of the axis of symmetry of an electromagnet could be described by the laws associated with light passing through a glass lens. In that year, then, electron ballistics gave way to electron optics and mentalities changed in a way that made the notion of an electron microscope conceivable. We follow the travels of the electron during its first 100 years, first through tubes and oscilloscopes, then through the electrostatic and magnetic lenses of the first primitive microscopes of the 1930s; the first scanning instruments were also built in that first decade of electron microscopy but only emerged from the shadows in the 1960s. In the 1940s, ways of correcting lens aberrations were proposed by Scherzer and Gabor and the first aberration correctors appeared in the 1950s but it is only now that they are being made to work and Gabor’s holography too is still not in widespread use. With the centenary of the electron, we meet miniature electron microscope columns, constructed by electrons themselves and microscopes whose resolution enables us to see the structure of specimens, atom by atom. It is all the more disconcerting to recall that we still do not really understand how an electron beam can behave as a set of particles, which can be observed arriving one by one on a fluorescent screen, and as a wave field, producing interference fringes.
