Abstract:
Using a binary microlens of diameter 14 $\mu$m and focal length 532 nm (numerical aperture NA = 0.997), we focus a 633-nm laser beam composed of a mixture of radially and linearly polarized waves obtained by reflection of a linearly polarized Gaussian beam from a gold-coated subwavelength binary four-zone diffractive optical microelement (micropolarizer) of size 100 x 100 $\mu$m to a near-surface, near-circular focal spot of size (0.37$±$0.02)$\lambda$ and (0.39$±$0.02)$\lambda$, where $\lambda$ is wavelength. A linearly polarized light beam forms an elliptical focal spot with diameters (0.35$±$0.02)$\lambda$ and (0.41$±$0.02)$\lambda$. Both focal spots have the area of 0.133$\lambda^{2}$. Subwavelength focusing using two microoptical components (a binary microlens and a micropolarizer) is suggested for the first time.