Limit Of Phase Only Approach In Micro–Lens Design

Abstract

Phase only approach (POA) is generally used to analyze diffractive optical elements (DOEs) such as micro–lenses. We used 3–D finite difference time domain (FDTD) method with perfect matched layer (PML) absorbing boundary conditions to test several micro–lenses that were designed based on phase only approach to evaluate the accuracy of this approach. It is shown that if the focal length is greater than 80λ and 25λ for 2π and 4π phase resets, respectively, the error in the main lobe diffraction efficiency will be less than 10%. Key words: Phase only approach (POA); diffractive optical elements (DOEs); micro–lens