Fig. 3
From: Coaxial superposition of Bessel beams by discretized spiral axicons
Resulting field distribution for rp=32 μm,M=15,λ=632.8 nm and z=12 mm: (left column) intensity distribution, (middle column) phase distribution with vortices indicated by black circles, (right column) zero contour lines of real and imaginary part with positive and negative charged vortices indicated by blue and red circles, respectively, for (a)–(c) N=3, (d)-(f) N=4, (g)-(i) N=5 and (j)-(l) N=6 blades