Design Konzepte für breitbandige hoch effiziente DOEs

Efficiency of diffractive lenses decrease for wavelengths deviating from design wavelength, which prevents them from a broader use in optical systems and consequently, usage is mostly limited to applications with small spectral bandwidth. This well known drawback holds for all diffractive elements (DEs) made of a single material, as they usually can be optimally designed only for a single wavelength. This can be overcome by special diffractive lenses consisting of two materials with different dispersion. Several design-concepts for broadband high-efficiency diffractive lenses so-called efficiency-achromatic diffractive elements (EA-DEs), are presented. Starting with surface relief profiles well known from the literature we present the following new approaches together with their properties: 1) gradient-index EA-DEs, 2) sub-wavelength EA-DEs, and 3) the so-called cut-and-paste design.