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It is shown that in a constant-velocity waveguide, the periodic diffraction focusing of an acoustic field gives rise to a "beam" interference structure in the corresponding spatial regions.

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Possibilities for using spatially localized acoustic noise sources for tomographical reconstruction of inhomogeneities in oceanic waveguides are discussed in this work. According to the method presented here, the average characteristics of partially coherent wave bundles formed in such waveguides, are modeled and analyzed. A differential probing scheme is developed for the case where spatially localized inhomogeneities couple the acoustic energy among different acoustic bundles. It is shown that this effect gives rise to possibilitiesfor estimating the spatial distribution of inhomogeneities along the acoustic path between the source and observation region. This then allows the possibility of imaging the inhomogeneities.The influence of coherence distortion of the acoustic illuminating waves on Fresnel diffraction tomography in the ocean is discussed. Applications to oceanic fronts and mesoscale oceanic inhomogeneities are presented.The use of ships as partially coherent space/ time acoustic noise sources for tomographical reconstruction is mentioned.