| CPC G02B 27/0172 (2013.01) [B29D 11/00769 (2013.01); G02B 1/002 (2013.01); G02B 1/11 (2013.01); G02B 27/4205 (2013.01); G02B 27/44 (2013.01)] | 20 Claims |

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1. A head-mounted display, comprising:
an image source configured to provide an image beam;
an optical element comprising a flat first surface, a flat second surface opposing the first surface, and a buried diffractive grating spaced from and disposed between the first surface and the second surface, the buried diffractive grating comprising a plurality of nonsolid pockets interspaced with a material, wherein the material has a refractive index that is substantially equal to a refractive index of the first surface and a refractive index of the second surface;
wherein the optical element is configured to convert the image beam into an output image by diffracting the beam through the buried diffractive grating, propagating the image beam through the optical element through reflection off the first and second surfaces, and directing the image beam through at least one of the first or second surfaces of the optical element.
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