DITHERED HOLOGRAPHIC FRONTLIGHT

摘要

A reflective or transmissive hologram may be used to extract light from a waveguide. The hologram may be formed by separately exposing each of a plurality of areas of a holographic medium with object beams and/or reference beams having attributes (e.g., illumination angles) that vary randomly or pseudorandomly over the entire hologram. The areas may be contiguous (e.g., in a tiled pattern) or overlapping. In some embodiments, the spacing and/or orientation of the diffraction gratings may vary from area to area. For example, the spacing and/or orientation of the diffraction gratings may vary randomly or pseudorandomly from area to area. Some parts of the hologram may intentionally be made relatively more or relatively less efficient at extracting light from the waveguide.