Fig. 1. Schematic of phase compression of axicon. (a) Refractive axicon; (b) Fresnel axicon; (c) diffractive axicon

Fig. 2. Theoretical analysis of the diffraction of axicon

Fig. 3. Radial intensity distributions. (a) Position at L/4; (b) position at L/2

Fig. 4. Structures schematic of helical axicon

Fig. 5. Intensity distribution behind helical axicon. (a) l=1; (b) l=3; (c) l=5

Fig. 6. Phase distribution of axicon array

Fig. 7. Intensity distribution behind axicon array