We study binary axicons of period 4, 6, and 8 �µm fabricated by photolithography with a 1 �µm resolution, 500nm depth, and 4mm\r\ndiameter. Near-field diffraction focal spots varying in diameter from 3.5? to 4.5? (for the axicon of period T = 4 �µm) and from 5?\r\nto 8? (for the axicon with T = 8 �µm) are experimentally found on the optical axis at a distance of up to 40 �µm from the axicon for\r\nthe wavelength ? = 0.532 �µm. The first focal spot is found at distance 2 �µm (T = 4 �µm), with the period of the focal spots being\r\n2 �µm (T = 4 �µm) and 4 �µm (T = 8 �µm). Diffraction of linearly polarized plane and diverging waves is simulated using FullWAVE\r\n(RSoft) and a proprietary program BOR-FDTD, which implement finite-difference schemes to solve three-dimensional Maxwellâ��s\r\nequations in the Cartesian and cylindrical coordinates. The numerically simulated values for diameters of the near-field focal spots\r\nfor the axicon of period T = 4 �µm are in good agreement with the experimental values.
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