VIEWING OPTICS ASSEMBLY FOR AUGMENTED REALITY SYSTEM
A viewing optics assembly for augmented reality includes a projector configured to generate image light and an eyepiece optically coupled to the projector. The eyepiece includes at least one eyepiece layer comprising a waveguide having a surface, an incoupling grating coupled to the waveguide, and an outcoupling grating coupled to the waveguide. The outcoupling grating comprises a first array of first ridges protruding from the surface of the waveguide, each of the first ridges having a first height in a direction perpendicular to the surface and a first width in a direction parallel to the surface and a plurality of second ridges, each of the plurality of second ridges protruding from a respective first ridge of the first ridges and having a second height and a second width. At least one of the first width or the second width varies as a function of position across the surface.
1 . A viewing optics assembly for augmented reality, the viewing optics assembly comprising:
a projector configured to generate image light;
an eyepiece optically coupled to the projector, wherein the eyepiece includes at least one eyepiece layer comprising:
a waveguide having a surface;
an incoupling grating coupled to the waveguide; and
an outcoupling grating coupled to the waveguide, wherein the outcoupling grating comprises:
a first array of first ridges protruding from the surface of the waveguide, each of the first ridges having a first height in a direction perpendicular to the surface and a first width in a direction parallel to the surface; and
a plurality of second ridges, each of the plurality of second ridges protruding from a respective first ridge of the first ridges and having a second height and a second width, wherein at least one of the first width or the second width varies as a function of position across the surface.
2 . The viewing optics assembly of claim 1 wherein a ratio between the first width and the second width varies as a function of position across the surface.
3 . The viewing optics assembly of claim 2 wherein the ratio ranges from 8:7 to 8:3.
4 . The viewing optics assembly of claim 1 wherein the first array of first ridges comprises a periodic array having a period.
5 . The viewing optics assembly of claim 1 wherein the second height is greater than the first height.
6 . The viewing optics assembly of claim 1 wherein the second width is less than the first width.
7 . The viewing optics assembly of claim 1 wherein the projector comprises:
a light source;
a spatial light modulator; and
relay optics.
8 . The viewing optics assembly of claim 1 wherein the incoupling grating is configured to diffract image light into the waveguide.
9 . The viewing optics assembly of claim 8 further comprising an orthogonal pupil expander grating configured to receive image light from the incoupling grating and diffract light parallel to the surface.
10 . The viewing optics assembly of claim 9 wherein the orthogonal pupil expander grating spatially overlaps with the outcoupling grating.
11 . The viewing optics assembly of claim 9 wherein the orthogonal pupil expander grating and the outcoupling grating are disposed on the surface.
12 . The viewing optics assembly of claim 9 wherein at least one of the orthogonal pupil expander grating or the outcoupling grating are disposed on a second surface opposite the surface.
13 . The viewing optics assembly of claim 1 wherein the at least one eyepiece layer comprises three eyepiece layers.
14 . The viewing optics assembly of claim 13 wherein each of the three eyepiece layers corresponds to one of the primary colors: red, green, or blue.
15 . The viewing optics assembly of claim 1 wherein the first width and the second width are selected such that the outcoupling grating has a first order reflection efficiency greater than a first order transmission efficiency.
16 . The viewing optics assembly of claim 15 wherein a ratio of the first order reflection efficiency and the first order transmission efficiency is greater than 2.
17 . The viewing optics assembly of claim 1 wherein each of the first width and each of the second width are varied such that a first order reflection efficiency of the outcoupling grating varies as a function of a position across the surface in the direction parallel to the surface.
18 . The viewing optics assembly of claim 17 wherein the first order reflection efficiency of the outcoupling grating increases as a function of the position across the surface.
19 . The viewing optics assembly of claim 18 wherein the first order reflection efficiency of the outcoupling grating increases linearly as a function of the position across the surface.
20 . The viewing optics assembly of claim 1 wherein the surface faces away from an eye of a user and the outcoupling grating is configured to diffract image light including virtual content to the eye of the user.