Open AccessDiffraction theory of high numerical aperture subwavelength circular binary phase Fresnel zone plate
Author(s) -
Yaoju Zhang,
Hongchang An,
Dong Zhang,
Guihua Cui,
Xiukai Ruan
Publication year - 2014
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.22.027425
Subject(s) - zone plate , optics , fresnel zone , diffraction , fresnel diffraction , fresnel number , kirchhoff's diffraction formula , finite difference time domain method , fresnel equations , rayleigh scattering , numerical aperture , physics , scattering , refractive index , wavelength
An analytical model of vector formalism is proposed to investigate the diffraction of high numerical aperture subwavelength circular binary phase Fresnel zone plate (FZP). In the proposed model, the scattering on the FZP's surface, reflection and refraction within groove zones are considered and diffraction fields are calculated using the vector Rayleigh-Sommerfeld integral. The numerical results obtained by the proposed phase thick FZP (TFZP) model show a good agreement with those obtained by the finite-difference time-domain (FDTD) method within the effective extent of etch depth. The optimal etch depths predicted by both methods are approximately equal. The analytical TFZP model is very useful for designing a phase and hybrid amplitude-phase FZP with high-NA and short focal length.