Quasi-optical waveguide-mode converters using a pair of phase correction mirrors

This paper describes a quasi-optical method for the conversion of modes transmitted through highly oversized circular waveguides. A waveguide-mode is radiated once from a waveguide cut in the form of a radiation beam, which is then properly shaped by two curved mirrors and directed back into the waveguide. The curved mirror shapes are iteratively and automatically determined for given propagation distances using the design technique for phase correction mirrors. The proposed method gives favorable results in designing a waveguide expander/reducer, a TE₀₁-TE₀₂ mode converter, and a TE₀₁-HE₁₁ mode converter.     

A variational approach to dynamics of simple ionic crystals at high temperatures

The variational theory of anharmonic lattice dynamics is applied to the sodium chloride structure. The Coulomb and the inverse-power repulsive pair potential between ions are used. The mean-square displacements (MSDs) at zero pressure for individual ions, i.e., cation and anion, are calculated as a function of temperature without use of any fit parameters. It is shown that the ratio of the MSDs for anion and cation depends strongly on the ionic-radius ratio. The average MSDs are in reasonably good agreement with the experimental data obtained by a Bragg diffraction technique. A discussion is given of the relation between the divergent behavior of the MSDs which we find at some critical temperature and the observed melting point.A Humboldt fellow on leave of absence from Department of Engineering Science, Hokkaido University, Sapporo 060, Japan     

Chaotic behaviours of a system of three disk dynamos

A system of three disk dynamos with six degrees of freedom has been analyzed numerically. It exhibits rich behaviours which are limit cycles, T²-tori and two kinds of chaos. A doubling of T²-torus, frequency lockings and transition from T²-torus to chaos are observed.     

The electronic viewpoint on the morphology of the microclusters

A possible role of the electron interaction in the morphology of the microcluster is studied. Highly symmetrical configuration leads to highly degenerated single-particlelevels. They are preferable for the emergence of the magnetic polarization (the Hundtendency). On the other hand, the splitting of the degenerated Fermi level due to the lowering of the symmetry sometimes reduces the ground state energy (the Jahn-Teller tendency). The conflict of these two tendencies is investigated by a simple model.On leave from Department of Physics, Faculty of Science, Kyoto University, Kyoto, 606 Japan     

A Hologram Computer-Aided Design Tool Extends the Function for Designing and Analyzing Holographic Optical Elements Illuminated by Multiple Point-Sources

The function of a hologram computer-aided design tool which the authors have developed are extended to handle both designing and analyzing holograms illuminated by a two or three-dimensional white-light image. The ability to search for an optimum image plane is also now possible. HOE lenses illuminated by multiple point-sources and by a point-source with a certain spectral bandwidth are designed and analyzed using the extended functions. Accuracy and usefulness of the functions are demonstrated from the results of the design and analysis.