Design of compact projection lenses using double‐layered diffractive optical elements

Abstract— Based on several special properties of diffractive optical elements (DOEs) such as savings in mass and to freely modulate the wavefront of incident light, a new compact projection lens with double‐layered DOEs is presented. It is comprised of five lenses and has nearly half the weight of its original structure. The modulation transfer function (MTF) value on‐axis is 0.7 at a spatial frequency of 33 lp/mm and more than 0.3 for all off‐axis values, which satisfies the requirement of a color‐filter‐type liquid‐crystal‐on‐silicon (LCoS) 0.59‐in. display with a SVGA resolution. The maximum distortion is 0.46%.