Graded dielectric combiner and associated fabrication method

Abstract

The graded dielectric combiner, such as for a dual heads up display (HUD) combiner, is fabricated by depositing a predetermined number of dielectric layers upon a substrate and by thereafter selectively removing at least some of the dielectric layers from a graded portion of the dielectric combiner. As a result, the number of dielectric layers disposed upon the substrate will vary across the graded portion of the combiner. More specifically, the graded portion of the combiner may include a number of bands. A predetermined percentage of each band includes the predetermined number of dielectric layers, while the remainder of each band includes less than the predetermined number of dielectric layers. Since the dielectric layers are deposited in a conventional fashion, however, the thickness of each remaining dielectric layer will be uniform across the substrate. The graded dielectric combiners can thereafter be assembled to form a dual HUD combiner having first and second combiners in which one or both combiners are graded within the overlap region, thereby reducing, if not eliminating, the dark band and other visual nonuniformities introduced by the overlapped combiners of conventional dual HUD combiners.