Scattering phenomena in volume holograms with strong coupling.

A qualitative analysis of various diffraction phenomena, visible in scattering volume gratings, like scattering rings, Kossel lines, dark scattering rings, is made for gratings including higher order harmonics and for gratings with strong coupling. An interference phenomenon, explained by the dynamical theory of diffraction, is demonstrated. In order to simplify the analysis of these phenomena and diffraction in volume gratings in general, a modification of the traditional Ewald construction is introduced. This modification is geometrically equivalent but physically more consistent and, for instance, defines how the observer is related to the wave vector sphere and also permits the location and extent of the intermodulation spectrum to be easily constructed. The construction is applied to the recording and readout of multiple recording by superposition in volume holograms as an illustration.