Comparative modeling two methods of sharp focusing with zone plate using
S.S. Stafeev, V.V.Kotlyar

Full text of article: Russian language.

Abstract:
We simulated a focusing of radially-polarized mode using two methods: FDTD and Richards-Wolf equations. It was shown that both methods demonstrate the ability of overcoming the diffraction limit using a zone plate with radius R = 20λ and R-TEM01 mode with radius ω = 10λ. The overcoming of the diffraction limit was observed when numerical aperture of the zone plate was more than NA = 0,97 for FDTD-method and more than NA = 0,96 for Richards-Wolf equation.  The relative error of the width of the focal spot was less than 6%.

Key words:
sharp focusing, radial polarization, zone plate, radial-FDTD, Richards-Wolf equation.

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