US 12,345,891 B2
Device and method for compensating effects of pantoscopic tilt or wrap/sweep tilt on an image presented on an augmented reality or virtual reality display
Mohmed Salim Valera, Sutton Coldfield (GB); and David Louis Maxime Poussin, London (GB)
Assigned to Snap Inc., Santa Monica, CA (US)
Appl. No. 18/263,837
Filed by Snap Inc., Santa Monica, CA (US)
PCT Filed Dec. 7, 2021, PCT No. PCT/EP2021/084652
§ 371(c)(1), (2) Date Aug. 1, 2023,
PCT Pub. No. WO2022/167125, PCT Pub. Date Aug. 11, 2022.
Claims priority of application No. 21155624 (EP), filed on Feb. 5, 2021.
Prior Publication US 2024/0094536 A1, Mar. 21, 2024
Int. Cl. G02B 27/01 (2006.01); F21V 8/00 (2006.01); G02B 27/42 (2006.01)
CPC G02B 27/0172 (2013.01) [G02B 6/0016 (2013.01); G02B 27/4222 (2013.01); G02B 27/4272 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An optical device for use in an augmented reality or virtual reality display, comprising:
a waveguide;
an input diffractive optical element positioned in or on the waveguide, configured to receive light from a projector and couple it into the waveguide so that it is captured within the waveguide under total internal reflection, wherein the input diffractive optical element has an input grating vector in a plane of the waveguide; and
an output element comprising a plurality of optical structures arranged in an array to provide a first diffractive optical element and a second diffractive optical element overlaid on one another in or on the waveguide and having first and second grating vectors respectively in the plane of the waveguide, wherein the first diffractive optical element is configured to receive light from the input diffractive optical element and to couple it towards the second diffractive optical element, and wherein the second diffractive optical element is configured to receive light from the first diffractive optical element and to couple it out of the waveguide towards a viewer, wherein:
the input grating vector, the first grating vector and the second grating vector have different respective magnitudes, resulting in an asymmetry in angular relationships among the grating vectors that at least partially compensates for a non-zero angle of incidence of light from the projector received by the input diffractive optical element;
each of the first and second diffractive optical elements is configured to receive light from the input diffractive optical element 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;
the array comprises a plurality of unit cells where each unit cell is in the shape of a non-rectangular parallelogram having sides of unequal length, at least one optical structure being provided within each unit cell, the at least one optical structure within each unit cell having a shape formed by two overlapping parallelograms that includes a plurality of straight sides forming a closed polygon, at least some of the straight sides of each optical structure being parallel with the sides of the parallelogram unit cell; and
a vector addition of the input grating vector, the first grating vector and the second grating vector sums to zero.