Grazing-incidence antireflection films. I. Basic theory

Abstract

We discuss the possibility of a new interference technique for x-ray and \ensuremath{\gamma}-ray optics---the simple idea of grazing-incidence antireflection films (GIAR films)---for creating high-efficiency antireflection coatings for near-grazing-incidence reflection of hard x rays and \ensuremath{\gamma} rays. The motivation is the possible application to producing ``ultranarrow'' bandpass filters for synchrotron radiation with frequency widths \ensuremath{\approxeq}${10}^{\mathrm{\ensuremath{-}}8}$--${10}^{\mathrm{\ensuremath{-}}6}$ eV, giving a unique high-resolution, long-coherence-length, x-ray source for probing soft inelastic excitations and opening up new possibilities in x-ray interferometry. In this first of two papers on nonresonant GIAR films, we develop the basic theory and discuss in detail the simplest ideas for achieving antireflection films---impedance-matched quarter-wave films and damping stabilized solutions---which can both be obtained by coating a high-density mirror with a single lower-density film.