Diffraction in a stratified region of a high numerical aperture Fresnel zone plate: a simple and rigorous integral...

An algorithm for calculating the field distribution of a high numerical aperture Fresnel zone plate (FZP) in stratified media is presented, which is based on the vector angular spectrum method. The diffraction problem of FZP is solved for the case of a multilayer film with planar interfaces perpendicular to the optical axis. The solution is obtained in a rigorous mathematical manner and it satisfies the homogeneous wave equations. The electric strength vector of the transmitted and reflected field in the multilayer media is obtained for any polarized beam normally incident onto a binary phase circular FZP. For radially-, azimuthally- and linearly-polarized beam, the electric field in the focal region can be simplified as double or single integral, which can be readily used for numerical computation.