  Manifestations of orbital angular momentum induced effects in the diffraction
of a radially polarized vector beam by an off-axis tilted aperture are studied
both experimentally and theoretically. Experiments were carried out to extract
the degree of circular polarization, which was shown to be proportional to the
on-axis component of the spin angular momentum density. We report a clear
separation of the regions of dominance of the right and left circular
polarizations associated with positive and negative topological charges
respectively, which is reminiscent of the standard vortex-induced transverse
shift, albeit in the diffraction scenario. The experimental results are
supported by model simulations and the agreement is quite satisfactory. The
results are useful to appreciate the orbit-orbit related effects due to
unavoidable misalignment problems (especially for vortex beams).
