517591.fig.0018a
(a)
517591.fig.0018b
(b)
517591.fig.0018c
(c)
517591.fig.0018d
(d)
517591.fig.0018e
(e)
Figure 18: Fringes obtained due to interference between a vortex of charge +3 with (a) another beam with charge −3 (b) an on-axis plane wave (c) an off-axis plane wave. Interferograms obtained when both the interfering beams have off centred vortices of (d) opposite unequal charges (e) same signed unequal charges.