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JOURNALS // Computer Optics // Archive

Computer Optics, 2014 Volume 38, Issue 4, Pages 606–613 (Mi co164)

OPTO-IT

Sharp focusing of a mixture of radially and linearly polarized beams using a binary microlens

S. S. Stafeevab, L. O'Faolainc, M. I. Shanina (Kotlyar)b, A. G. Nalimovab, V. V. Kotlyarab

a Samara State Aerospace University
b Image Processing Systems Institute, Russian Academy of Sciences
c School of Physics and Astronomy of the University of St. Andrews, Scotland

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.

Keywords: radial polarization, reflective subwavelength diffractive grating, binary optics, micro-optics, subwalength focal spot, near-field microscopy.

Received: 31.10.2014



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