Fig. 8
From: Coaxial superposition of Bessel beams by discretized spiral axicons
Measurement of the discretized spiral axicon with N=6, rp=32 μm, aperture diameter D0=960 μm at z=18 mm illuminated by a helium-neon laser with λ=632.8 nm and 5mW power (a) intensity distribution with CCD-camera (4.75 μm×4.75 μm pixel) with 20× magnification; measured spot deviation obtained with a Shack-Hartmann sensor and 50× magnification of (b) on-axis and (c) off-axis vortex. Note, that the arrows representing the spot displacement are stretched by the same factor for a better overview