	US 12,204,112 B2
	Waveguide and diffraction grating for augmented reality or virtual reality display
Alexandra Crai, Abingdon (GB); Ciaran Phelan, Wallingford (GB); Mohmed Salim Ibrahim Valera, Sutton Coldfield (GB); and David Nicholas Crosby, Oxford (GB)
Assigned to Snap Inc., Santa Monica, CA (US)
Appl. No. 18/563,733
Filed by Snap Inc., Santa Monica, CA (US)
PCT Filed Jun. 6, 2022, PCT No. PCT/EP2022/065292 § 371(c)(1), (2) Date Nov. 22, 2023, PCT Pub. No. WO2022/258553, PCT Pub. Date Dec. 15, 2022.
Claims priority of application No. 21178594 (EP), filed on Jun. 9, 2021.
Prior Publication US 2024/0264444 A1, Aug. 8, 2024
Int. Cl. G02B 27/01 (2006.01); G02B 5/18 (2006.01); G02B 27/00 (2006.01); G06T 19/00 (2011.01)

CPC G02B 27/0172 (2013.01) [G02B 5/1819 (2013.01); G02B 27/0037 (2013.01); G06T 19/006 (2013.01)]

20 Claims

1. A waveguide for use in a virtual reality, VR, or augmented reality, AR, device, the waveguide comprising:

an input region configured to couple light into the waveguide so that it propagates under total internal reflection (TIR) within the waveguide; and

an output region comprising optical structures configured to receive image bearing light from the input region in a direction along a first axis, the output region providing diffractive interactions for light that propagates under TIR within the waveguide including a first diffractive interaction that outcouples light that is propagating along the first axis to a viewer, a second diffractive interaction that outcouples light that is propagating along a second axis perpendicular to the first axis to a viewer, and a third diffractive interaction that turns light such that it is caused to propagate under TIR within the waveguide along an axis that is perpendicular to the axis in which it is propagating prior to the third diffractive interaction;

wherein the output region comprises a plurality of zones each having different non-zero diffraction efficiencies for the first, second, and third diffractive interactions, the plurality of zones comprising:

a first zone; and

a second zone, located at a position along the second axis with respect to the first zone, wherein in the second zone the diffraction efficiency of:

the first diffractive interaction is: greater than the diffraction efficiency of the second diffractive interaction in the second zone, and is greater than the diffraction efficiency of the first diffractive interaction in the first zone, so as to reduce rainbow artefacts;

the second diffractive interaction is: greater than the diffraction efficiency of the first diffractive interaction in the second zone, and is greater than the diffraction efficiency of the second diffractive interaction in the first zone, so as to reduce rainbow artefacts.