Design and evaluation of diffractive optical elements; optimization by using iterative angular spectrum approach and evaluation based on vector diffraction theory

摘要

Diffractive optical elements (DOE) are used for various purposes, such as a beam shaper, beam splitter and so on. In order to design DOEs, iterative Fourier transform algorithm (IFTA) is widely used. IFTA is fast and effective optimization method and can handle large size data. In the IFTA, propagation in the far field and near field is described by Fourier transform and Fresnel transform, respectively. Iterative angular spectrum approach (IASA) is one of iterative methods based on angular spectrum technique. IASA adopt angular spectrum technique as expression of propagation in near field instead of Fresnel transform. Angular spectrum technique is based on scalar diffraction theory and satisfies Helmholtz equation; therefore angular spectrum technique is the accurate method for the calculation of diffraction.We designed a DOE by using IASA and evaluated its diffraction characteristics based on vector diffraction theory. In this paper, we report on the outcome.