Figure 5
From: Planar super-oscillatory lens for sub-diffraction optical needles at violet wavelengths
Central block SOL design for longer DOF.
(a), SEM image of Sample 2 which has a central block diameter of 12 µm and is designed with focal length of 10 µm and DOF of 6 µm; (b), (c), Experimental and simulated intensity of the diffraction patterns within propagation distance of 19 µm respectively; (d), Axial intensity distributions from theory (solid line) and experiment (dashed line with symbol); (e), FWHM of the spot in transverse direction: theory (solid line) and experiment (down triangle). The error bar comes from the spot size averaging along x and y directions. Insets show the transverse intensity distributions within area of 2 µm*2 µm at z = 8 µm to 12 µm in step of 1 µm.
