Formation of caustic beams in a refractive oceanic waveguide.

We consider the patterns in the formation of the spatial interference structure of an acoustic field excited in the near-surface channel of a vertical array consisting of point sources emitting a tonal signal inphase. It is established that when the array aperture is increased to a certain optimal size, only one caustic beam forms in the channel. As the array aperture further increases, the sequential formation of a certain number of beams after the first is observed. [ABSTRACT FROM AUTHOR]