  We have generated and propagated both diffracting and non-diffracting
speckles using the scattering of perfect optical vortices. The diffracting
speckles have been realized in the near field and non-diffracting speckles have
been realized in the far field, that is after taking the Fourier transform of
near-field speckles using a simple convex lens. The exact analytical
expressions have been provided for the size of both diffracting as well as
non-diffracting speckles and compared with our experimental results. We found
that the experimental results are in good agreement with the theoretical
results. These results may find applications in classical cryptography and
communication as we have both varying and non-varying random field patterns
with propagation distance.
