Patent ID: 11953685
Assignee: SNAP INC.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 5:
6. A method of manufacture of a waveguide for an augmented reality or virtual reality display, comprising the steps of:
providing a plurality of optical structures in a photonic crystal;
arranging the plurality of optical structures in an array to provide at least two diffractive optical elements, wherein each of the two diffractive optical elements is configured to receive light from an input direction and couple it towards the other diffractive optical element which can then act as an output diffractive optical element, providing outcoupled orders towards a viewer; and
providing the plurality of optical structures respectively each with a cross shape, when viewed in the plane of the waveguide, comprising twelve substantially straight sides, a first half of the sides having respective normal vectors at a first angle, and a second half of the sides having respective normal vectors at a second angle which is different to the first angle, wherein adjacent optical structures in the array are spaced apart from each another by a gap in a direction parallel to the diffractive optical elements, wherein the optical structures have a physical extent that extends in the direction parallel to the optical elements, wherein a lattice constant is defined by a sum of the physical extent and the gap, and the gap is defined as between 1 to 50% of the extent of the lattice constant;
wherein each optical structure of the plurality of optical structures are arranged in the photonic crystal in a unit cell having a parallelogram shape when viewed in the plane of the waveguide, wherein the lattice constant defines one side of the unit cell;
wherein the arrangement of the plurality of optical structures in the array has hexagonal symmetry;
providing an input diffractive optical element, separate from the at least two diffractive optical elements overlaid on one another in the waveguide, configured to couple light into the waveguide and to provide light to the plurality of optical structures in the array in the input direction.