Spectral methods for bulk and guided waves in weakly inhomogeneous media

Plane wave spectra localized around interference maxima provide the foundation for charting the propagation of source excited wavefields through weakly inhomogeneous bulk and layered environments. Attention is focused here on recent developments in spectral analysis, uniformization, restoration, and inversion, centered around the ‘bare bones’ spectral objects represented by ray fields in a bulk medium, by adiabatic modes in a layered medium, and by beams.