Influence of diffraction on formation of photon echo signals

A theoretical analysis is made of the formation of photon echo signals under one-photon resonance conditions when a medium is excited by light pulses with a finite transverse aperture. Basic equations are formulated and a method of solving these within the limits of perturbation theory using Green's functions is indicated. An analysis is made of some analytic solutions. An expression is derived to describe the spatial profile of the photon echo signal under diffraction conditions.