Step-discontinuity approach for non-paraxial diffractive optics

Abstract

An approximate method based on local field perturbations caused by abrupt transitions of the surface profile is described, which enables rapid approximate calculation of diffraction patterns of diffractive elements in the non-paraxial domain of diffractive optics. In this domain the simple complex-amplitude transmittance model based on scalar diffraction theory is no longer valid and rigorous computations are exceedingly time-consuming. Comparisons with rigorous diffraction theory show that the method is accurate for binary and multilevel profiles provided that the minimum feature size is larger than approximately one optical wavelength. The method is applied to the evaluation of the uniformity error of binary, four-level, and analogue array illuminators.