  The symmetry matching between the source and the lens results of fundamental
interest for lensing applications. In this work we have modeled an axisymmetric
gradient index (GRIN) lens made of rigid toroidal scatterers embedded in air
considering this symmetry matching with radially symmetric sources. The sound
amplification obtained in the focal spot of the reported lens (8.24 dB
experimentally) shows the efficiency of the axisymmetric lenses with respect to
the previous Cartesian acoustic GRIN lenses. The axisymmetric design opens new
possibilities in lensing applications in different branches of science and
technology.
