US 2019/0056591 A1 · OPTICAL WAVEGUIDE WITH MULTIPLE ANTIREFLECTIVE COATINGS

Abstract

An optical waveguide that performs both in-coupling and out-coupling of projected light is provided. The out-coupling region of the waveguide comprises a single-sided or double-sided diffraction grating with at least one of the grating structures conformally coated with a high refractive index material. To reduce the unwanted reflection of light on the waveguide surfaces coated with the high refractive index material, additional antireflective coatings are applied to the diffraction grating areas with the high refractive index coating. The additional antireflective coatings may be very thin to avoid in-coupling, and therefore avoid interference in one or more light rays propagating in the optical waveguide. Alternatively, the antireflective coatings may be very thick to promote in-coupling such that the resulting interference becomes consistent across all light rays propagating in the optical waveguide.

Claims20

Dependent claims

An optical waveguide for providing pupil expansion for augmented reality and virtual reality applications, the optical waveguide comprising:

a light-transmissive substrate including a plurality of internally reflective surfaces;
a first diffractive optical element formed on a first surface of the plurality of internally reflective surfaces, wherein the first diffractive optical element is adapted to in-couple light into the optical waveguide;
and
a second diffractive optical element formed on the first surface or a second surface of the plurality of internally reflective surfaces and adapted to out-couple light from the optical waveguide, wherein the second diffractive optical element comprises:
a diffraction relief grating structure;
a first coating, wherein the diffraction relief grating structure is embedded in the first coating;
and
a plurality of second coatings forming an anti-reflective structure that reduces reflections associated with the first coating.

5 more elements

Dependencies are inferred from the claim text.

Optical waveguide with multiple antireflective coatings

Life of this patent

Optical waveguide with multiple antireflective coatings

Life of this patent

Abstract

Claims20