Light focusing by a Fresnel binary zone plate with various design features
Yu.E. Geints1, E.K. Panina1, O.V. Minin2, I.V. Minin2
1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
2Siberian State University of Geosystems and Technologies, Novosibirsk, Russia
Keywords: Fresnel zone plates, light focusing, focal spot
Abstract
The results of the numerical simulations of binary phase Fresnel zone plates (FZP) of mesowavelength sizes and large aperture angles (NA ~ 1) are presented. The simulation allowed us to reveal the main regularities of the formation of the spatial optical near-field structure, as well as to optimize FZP design for obtaining the most intense focus. We show the dimensional parameters of FZP focal region to be sensitive both to the depth of phase zones etching and to the type of structural design of the plate. An increase in the number of Fresnel zones leads to the formation of external local focus with a greater intensity.
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