The nature of spatial resolution limitation in the hologram recording in the crystals LiNbO3

The amplitude of photoinduced holographic gratings in the crystals LiNbO3 is found to sharply decrease in the decrease of the distance between interference maxima. It is proved that this phenomenon is connected with the microscopic structure defects playing the important role in the processes of charge transfer. The defect regions, absorbing light, provide the crystal with free charges and are the places of both charge sources and runoffs. The distances between the runoffs limit the spatial resolution of the holographic grating. A model is suggested that relates photogalvanic current in ″homogeneous″ ferroelectric to macroscopic inhomogeneities.