  Bessel beams' great importance in optics lies in that these propagate without
spreading and can reconstruct themselves behind an obstruction placed across
their path. However, a rigorous wave-optics explanation of the latter property
is missing. In this work we study the reconstruction mechanism by means of a
wave-optics description. We obtain expressions for the minimum distance beyond
the obstruction at which the beam reconstructs itself, which are in close
agreement with the traditional one determined from geometrical optics. Our
results show that the physics underlying the self-healing mechanism can be
entirely explained in terms of the propagation of plane waves with radial wave
vectors lying on a ring.
