| 摘要 |
<p>An improved optical combiner useful in many applications. The combiner includes a substrate (10) with at least one aspheric surface and a diffraction-type reflective coating (12) formed on the substrate (10) for selectively reflecting radiation within one or more predetermined narrow band ranges of wavelengths impinging on the coating. The aspericity of the surface may be selected to compensate or balance optical aberations. The coating is advantageously a graded-index (16) coating (12), which eliminates the possible degradation of gelatin hologram coatings due to moisture. A process for applying the graded-index (16) coating (12) to a substrate (10) is disclosed. The variation in the index profile of the coating can be selected to provide the capability of combiners with multiple color reflectivity responses, or which allow use of display light sources of wider spectral bandwidth, resulting in a brighter image and improved angular bandwidth.</p> |
