A historical review is given of the discovery of electron diffraction as well as the succeeding development of electron diffraction studes. Efforts and struggles of early pioneers, both in abroad and in Japan, are described in some detail. It is pointed out that Japan's main contribution in the field of electron diffraction following Kikuchi's work of the cathoderay diffraction by mica crystals is characterized by efforts concentrated on“the electron diffraction physics”, in particular those related to the dynamical diffraction process and inelastic scattering. In this connection, discussions are given of a series of simple but typical examples of multi-wave problems that are related to some recent topics such as the critical-voltage effect. Also, reminiscence of Prof. Miyake's own works is presented, in which the main features of the phenomenon of surface-wave excitation are outlined.
Optical properties of neutrons for multibilayer films, which can be used for neutron monochromator, neutron supermirror, and neutron polarizer, have been investigated using time-of-flight technique. The experimental diffraction patterns were well fitted with those calculated after the plane wave Schrödinger equation for one dimensional periodic square potentials. The even-order Bragg reflections for the periodic potential, which should not be present according to the kinematical theory, were observed both in the experimental results and the calculated ones after the plane wave Schrödinger equation. The number of the bilayers necessary to gain 100% reflectivity for the main Bragg reflection is found 5-6 pairs for the thickness of 110Å of the Ni-Mn multibilayer, but much more layers are required for smaller thickness of the layers. The critical angle of total reflection for the Ni-Mn supermirror (52 bilayers) was improved up to twice as much as that of a simple Ni mirror. The magnetized Fe-Al multilayers with the thickness of 116Å (6 pairs) proved to afford 95% polarizability and 63% reflectivity, at the main peak of Bragg reflection.