Enlightening darkness to diffraction limit and beyond: comparison and optimization of different polarizations for dark spot generation |
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Authors: | Khonina Svetlana N Golub Ilya |
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Affiliation: | Image Processing Systems Institute of the Russian Academy of Sciences, Samara, Russia. khonina@smr.ru |
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Abstract: | We compare generation of a dark spot using focusing of beams with azimuthal polarizion, radial polarization with a vortex, and a circular polarization with either a first or second order vortex. By optimization of the amplitude-phase pupil, it is ascertained that azimuthal polarization is the most suitable one to obtain the diffraction bounded dark spot per se whose scalar approximation limit has FWHM=0.29λ. Consequently, for dark spot generation, this polarization plays the role of the radial polarization in creation of the diffraction-limited bright spot. Using azimuthal polarization, it is shown that an amplitude-phase filter allows generation of a subdiffractive dark spot in a prescribed finite area. |
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