2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/19486Interfaces between media with negative relative refractive index generically support propagating electromagnetic surface polariton modes with large wavenumber. The relation of these modes to a recent prediction by Pendry of ``perfect (real) image formation'' by a parallel slab of negative-refractive-index material is analyzed. The ``perfect image'' theory is found to be incomplete without inclusion of a large-wavenumber cutoff that derives from a necessary wavenumber-dependence of the constitutive relations, and which controls the resolution of the image.4 pages, (incl.3 figs), LaTeX (RevTeX4) Updated to cite earlier surface polariton work by R. Ruppin + minor correction to Fig.3. Conclusions restated more clearly v3. has an improved Fig 3 showing the polariton spectrum more accuratelyCondensed Mattertext