CRYSTALLINE WAVEGUIDES AND WEARABLE DEVICES CONTAINING THE SAME
A head-mounted display system includes: a head mounted display frame; a first eyepiece supported by the frame, the first eyepiece including a first substrate composed of a crystalline, transparent material having crystallographic axes in a first orientation with respect to the frame, the substrate having a first surface and a second surface opposite the first surface, the first eyepiece further including a first in-coupling element including a grating on the first surface, and a first out-coupling element including a grating on the first surface and/or a grating on the second surface; and a second eyepiece including a second substrate composed of the crystalline, transparent material having crystallographic axes in a second orientation with respect to the frame different from the first orientation, a second in-coupling element on either surface of the second substrate, and a second out-coupling element on either surface of the second substrate.
1 . A head mounted display, comprising:
a head mounted display frame;
a first eyepiece supported by the frame, the first eyepiece comprising a first substrate composed of a crystalline, transparent material having crystallographic axes in a first orientation with respect to the frame, the substrate having a first surface and a second surface opposite the first surface, the first eyepiece further comprising a first in-coupling element on the first surface, and a first out-coupling element on the first or second surface; and
a second eyepiece comprising a second substrate composed of the crystalline, transparent material having crystallographic axes in a second orientation with respect to the frame different from the first orientation, a second in-coupling element on either surface of the second substrate, and a second out-coupling element on either surface of the second substrate.
2 . (canceled)
3 . The head mounted display of claim 1 , wherein for both the first orientation and the second orientation, a first crystallographic axis of the crystallographic axes is oriented perpendicular to the surface of the respective substrate and a second crystallographic axis of the crystallographic axes is oriented in a plane of the substrate, and
wherein the first crystallographic axis is a Z-axis.
4 . The head mounted display of claim 3 , wherein the second crystallographic axis in the first orientation is perpendicular to the second crystallographic axis in the second orientation.
5 . The head mounted display of claim 3 , further comprising a light projection system configured to deliver unpolarized light to the first and second in-coupling elements.
6 . The head mounted display of claim 1 , wherein for both the first orientation and the second orientation, a first crystallographic axis of the crystallographic axes is oriented perpendicular to the surface of the respective substrate and a second crystallographic axis of the crystallographic axes is oriented in a plane of the substrate, and
wherein the first crystallographic axis is an X-axis.
7 . The head mounted display of claim 1 , wherein for both the first orientation and the second orientation, a first crystallographic axis of the crystallographic axes is oriented perpendicular to the surface of the respective substrate and a second crystallographic axis of the crystallographic axes is oriented in a plane of the substrate, and
wherein the first crystallographic axis is a Y-axis.
8 . (canceled)
9 . (canceled)
10 . The head mounted display of claim 1 , wherein a thickness of the first substrate varies across the first substrate, and
wherein the thickness of the first substrate at an edge of the substrate is smaller than a thickness of the first substrate away from the edge.
11 . The head mounted display of claim 1 , wherein for the first and second eyepieces, a shortest line between corresponding in-coupling element and out-coupling element defines a respective first direction for a corresponding eyepiece, and for the first substrate, a first crystallographic axis of the crystallographic axes is aligned parallel to the first direction, and for the second substrate, a second crystallographic axis of the crystallographic axes is aligned parallel to the first direction.
12 . (canceled)
13 . (canceled)
14 . The head mounted display of claim 1 , wherein the first and second substrates are components of first and second stacks of waveguides.
15 . The head mounted display of claim 1 , wherein the first and second eyepieces correspond to portions of first and second wafers, and a first orientation of a first optic axis is different from a second orientation of a second optic axis.
16 . (canceled)
17 . (canceled)
18 . The head mounted display of claim 1 , wherein the first surface supports a layer of a first dielectric material that extends over the first in-coupling element and the first out-coupling element, the first dielectric material having a refractive index of 1.5 or less, and
wherein the refractive index of the first dielectric material is in a range from 1.2 to 1.3.
19 . (canceled)
20 . (canceled)
21 . (canceled)
22 . The head mounted display of claim 1 , further comprising a layer of material disposed over the first and second in-coupling elements and the first and second out-coupling elements,
wherein said layer of material comprises a polymerized resin.
23 . (canceled)
24 . The head mounted display of claim 1 , wherein the first and second in-coupling elements and the first and second out-coupling elements are separated by spaces, and said spaces comprise exposed regions of the crystalline, transparent material.
25 . (canceled)
26 . An article comprising:
a wafer composed of a crystalline, transparent material having crystallographic axes in a first orientation with respect to a surface of the wafer, a thickness of the wafer varying across the surface of the wafer such that for a cross-sectional profile of the wafer, the thickness increases monotonically from edges of the wafer to a location of maximum thickness away from the edges; and
a plurality of optical elements on the surface of the wafer and spaced apart from each other, each optical element corresponding to a portion of the wafer for singulation into a component for an eyepiece for a head mounted display, each portion having the same thickness profile.
27 . (canceled)
28 . The article of claim 26 , wherein the respective optical element is a combined pupil expander, an exit pupil expander, or an orthogonal pupil expander.
29 . The article of claim 26 , wherein a difference between a maximum thickness and a minimum thickness is in a range of 1 to 500 nm.
30 . The article of claim 26 , wherein the wafer is circular.
31 . The article of claim 30 , wherein the thickness of the wafer follows a sector of the circular wafer.
32 . The article of claim 30 , wherein the plurality of optical elements are equally spaced from a center of the circular wafer.
33 . An eyepiece comprising:
a transparent, crystalline substrate composed of a material having a refractive index greater than 2.2, the substrate extending in a plane and having a thickness in a direction perpendicular to the plane that varies along a first direction in the plane and along a second direction in the plane substantially perpendicular to the second direction;
an in-coupling element supported by a first surface of the substrate; and
an optical element supported by the first surface and/or a second surface of the substrate opposite the first surface.
34 - 42 . (canceled)