title: Step-transition perturbation approach for pixel-structured nonparaxial diffractive elements.
abstract: An extension of an approximate step-transition perturbation method is presented that permits numerically efficient diffraction analysis of pixel-structured surface profiles in the nonparaxial domain. Comparison with the rigorous diffraction theory of gratings shows that the method is reasonably accurate provided that the pixel size exceeds approximately two wavelengths even if the structure contains isolated pixels.
authors.affiliation: Department of Physics, University of Joensuu, Finland.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Vallius
authors.forename: Markku
authors.initials: M
authors.lastname: Kuittinen
authors.forename: Jari
authors.initials: J
authors.lastname: Turunen
authors.forename: Ville
authors.initials: V
authors.lastname: Kettunen