Аннотация:A generalization of the calculation of the formation of ghost images in the course of backward four-photon mixingto the real situation of non-planar spatially limited pumping, which has a Gaussian profile of the fundamental lasermode, is developed, taking into account the specifics of theformation of phantom images. Computer images havebeen obtained that make it possible to estimate the spatial resolution of the systems. A relatively simple equivalentscheme for describing the process is proposed, which shows that the effect of diffraction in nonlinear systems issimilar to its role in ordinary linear optics with a limited aperture. A fiber-optic version of the formation of ghostimages is proposed, suitable for the study of hard-to-reachcavities and organs of the human body, which allow theintroduction of a thin fiber bundle there.