<title>High-efficiency replicated diffractive optics</title>

Abstract

Diffractive optics technology offers optical system designers new degrees of freedom that can be used to optimize the performance of optical systems. The zone spacing of a diffractive lens can be chosen to impart focusing power as well as aspheric correction to the emerging wavefront. The surface (or blaze) profile within a given zone determines the diffraction efficiency of the element, or in other words, determines how the incident energy is distributed among the various diffraction orders. Unless the zone profile is generated with high fidelity, incident energy will be distributed into extraneous diffraction orders, which generally reduces the optical system performance. Several diffractive optical components have been fabricated using replication techniques that provide high-efficiency and accurate wavefront generation. Typical minimum efficiency measurements at the design wavelength for diffractive zone spacings greater than 10 micrometers are 95% or above. For minimum zone features as small as 5 micrometers , the measured efficiency is greater than 85% at the design wavelength. The integrated diffraction efficiency, which is a weighted measure of the efficiency across the clear aperture, is typically 2 - 3% more than the efficiency measurement at the minimum feature.