Systems, methods, and devices for adhesion of interior waveguide pillars
In some embodiments, a near-eye, near-eye display system comprises a stack of waveguides having pillars in a central, active portion of the waveguides. The active portion may include light outcoupling optical elements configured to outcouple image light from the waveguides towards the eye of a viewer. The pillars extend between and separate neighboring ones of the waveguides. The light outcoupling optical elements may include diffractive optical elements that are formed simultaneously with the pillars, for example, by imprinting or casting. The pillars are disposed on one or more major surfaces of each of the waveguides. The pillars may define a distance between two adjacent waveguides of the stack of waveguides. The pillars may be bonded to adjacent waveguides may be using one or more of the systems, methods, or devices herein. The bonding provides a high level of thermal stability to the waveguide stack, to resist deformation as temperatures change.
1 . A near-eye display system comprising:
a stack of waveguides configured to display images by outputting image light, the stack of waveguides comprising:
a first waveguide comprising an optically transmissive body, a first major surface, and a pillar integral with the optically transmissive body, the pillar extending vertically from the first major surface;
a second waveguide comprising an optically transmissive body and a second major surface, the second major surface facing and spaced apart from the first major surface of the first waveguide by the pillar;
one or more diffractive optical elements in a central area of the first major surface of the first waveguide, wherein the pillar is located in the central area; and
an adhesive on a top surface of the pillar, the adhesive attaching the pillar to the second major surface of the second waveguide,
wherein the one or more diffractive optical elements include out-coupling optical elements configured to out-couple light propagating within the optically transmissive body of the first waveguide,
wherein the optically transmissive body of the first waveguide comprises a first composition of a UV curable material and at least the adhesive on the pillar comprises a second composition of a UV curable material different from the first composition, and
wherein the second composition comprises a lower concentration of photoinitiator than the first composition.
2 . The near-eye display system of claim 1 , further comprising a spacer integral with the optically transmissive body, the spacer extending vertically from the first major surface, wherein the spacer extends laterally along a perimeter of the first waveguide.
3 . The near-eye display system of claim 2 , wherein the spacer defines an edge of the first waveguide.
4 . The near-eye display system of claim 2 , wherein the first waveguide comprises a plurality of spacers extending vertically from the first major surface and laterally along a perimeter of the first waveguide.
5 . The near-eye display system of claim 1 , wherein the top surface comprises a roughened surface.
6 . The near-eye display system of claim 1 , wherein the pillar comprises a maximum transverse cross-sectional dimension of 500 μm or less.
7 . The near-eye display system of claim 1 , wherein the pillar comprises a maximum transverse cross-sectional dimension of 300 μm or less.
8 . The near-eye display system of claim 1 , wherein the pillar comprises a maximum transverse cross-sectional dimension of 100 μm or less.
9 . The near-eye display system of claim 1 , wherein the second major surface of the second waveguide comprises an indentation accommodating the pillar in the indentation.
10 . The near-eye display system of claim 9 , wherein the stack of waveguides comprises a plurality of waveguides, wherein two or more waveguides of the plurality of waveguides comprise a pillar and an indentation, wherein the indentations accommodate pillars of underlying waveguides.
11 . The near-eye display system of claim 1 , wherein the pillar comprises a shape selected from the group consisting of rectangular prism, rectangular pyramid, triangular prism, triangular pyramid, cylinder, and cone.
12 . The near-eye display system of claim 1 , wherein the first and the second waveguide are separated by an air gap having a size defined by the pillar and adhesive.
13 . The near-eye display system of claim 1 , wherein the one or more diffractive optical elements comprise: in-coupling optical elements configured to in-couple incident image light, wherein the out-coupling optical elements are disposed within the central area.
14 . The near-eye display system of claim 13 , further comprising a light projector system configured to project the image light to the in-coupling optical elements.
15 . A near-eye display system comprising: an eyepiece comprising:
a waveguide comprising:
an optically transmissive body comprising at least one pillar integral with the optically transmissive body; and
out-coupling optical elements configured to out-couple light propagating within the optically transmissive body; and
an overlying waveguide spaced from the waveguide by the at least one pillar;
wherein the optically transmissive body comprises a first composition and at least a tip of the at least one pillar comprises a second composition different from the first composition, and
wherein the second composition comprises a lower concentration of photoinitiator than the first composition, and wherein the second composition comprises at least one of a transparent material, a hydrophilic or superhydrophilic material, or a hydroxyl group.
16 . The near-eye display system of claim 15 , wherein the out-coupling optical elements comprises a diffractive grating comprising a plurality of protrusions and intervening recesses on a major surface of the optically transmissive body, wherein the at least one pillar extends from the major surface to a height greater than a height of the plurality of protrusions.
17 . The near-eye display system of claim 15 , wherein the second composition comprises at least the adhesion-promoting layer and wherein the adhesion-promoting layer comprises a silane mixture.
18 . The near-eye display system of claim 15 , wherein the second composition comprises at least the adhesion-promoting layer and wherein the adhesion-promoting layer forms a top surface of the at least one pillar.