Polymer eyepiece assemblies for augmented and mixed reality systems
Fabrication of augmented reality (AR) and mixed reality (MR) polymer eyepiece assemblies and the resulting AR/MR polymer eyepiece assemblies may include one or more features, separately or in any appropriate combination, to compensate for expected deformation and to maintain substantially uniform gaps between polymer layers. Such features include fabricating polymer eyepiece assemblies with components having coefficients of thermal expansion (CTE) that are substantially the same; modifying the surface chemistry or structure of one or more polymer layers to increase hydrophobicity or omniphobicity of the polymer layer; disposing adhesive between adjacent polymer layers in continuous and/or extended configurations; and disposing microspheres of different sizes at selected locations between polymer layers.
1 . An eyepiece assembly comprising:
a first cover layer, wherein the first cover layer is an eye side cover layer;
a second cover layer, wherein the second cover layer is a world side cover layer;
a multiplicity of optical waveguides positioned between the first cover layer and the second cover layer, wherein the first cover layer is adjacent to a first optical waveguide and the second cover layer is adjacent to a second optical waveguide; and
an adhesive between:
the first cover layer and the first optical waveguide,
the second cover layer and the second optical waveguide, and
adjacent pairs of optical waveguides,
wherein:
each optical waveguide comprises a grating region comprising an orthogonal pupil expander region and an exit pupil expander region, and further comprising:
first microspheres positioned in an adhesive arranged around a perimeter of each of the grating regions; and
second microspheres positioned between adjacent optical waveguides in a region between the orthogonal pupil expander region and the exit pupil expander region,
wherein a diameter of the second microspheres exceeds a diameter of the first microspheres.
2 . The eyepiece assembly of claim 1 , wherein a gap between adjacent pairs of optical waveguides is substantially uniform.
3 . The eyepiece assembly of claim 1 , further comprising:
a first additional extended portion of adhesive proximate an interface between the orthogonal pupil expander region and the exit pupil expander region and between the grating region and the adhesive around the perimeter of the grating region; and
third microspheres positioned in the first additional extended portion of adhesive.
4 . The eyepiece assembly of claim 1 , wherein the first cover layer, the second cover layer, and each optical waveguide of the multiplicity of optical waveguides comprises a polymer material, and a coefficient of thermal expansion of the polymer material and the adhesive is substantially the same.
5 . The eyepiece assembly of claim 4 , wherein the first cover layer, the second cover layer, and the multiplicity of optical waveguides comprise the same polymer material.
6 . The eyepiece assembly of claim 4 , wherein the coefficient of thermal expansion of the polymer material and the adhesive is in a range of 30 μm/m° C. to 150 μm/m° C.
7 . The eyepiece assembly of claim 4 , wherein the coefficient of thermal expansion of the polymer material and the adhesive is substantially the same over a temperature range of about 20° C. to about 65° C.
8 . The eyepiece assembly of claim 1 , wherein the adhesive is arranged in one or more extended portions around a perimeter of each of the grating regions.
9 . The eyepiece assembly of claim 8 , further comprising a first additional extended portion of adhesive proximate an interface between the orthogonal pupil expander region and the exit pupil expander region and between the grating region and the adhesive around the perimeter of the grating region.
10 . The eyepiece assembly of claim 9 , wherein the first additional extended portion of adhesive is L-shaped.
11 . The eyepiece assembly of claim 9 , further comprising a second additional extended portion of adhesive proximate the first additional extended portion of adhesive and between the first additional portion of adhesive and the adhesive around the perimeter of the grating region.
12 . The eyepiece assembly of claim 8 , further comprising an incoupling grating region, and further comprising an additional extended portion of adhesive proximate the incoupling grating region and between the incoupling grating region and the adhesive around the perimeter of the grating region.
13 . The eyepiece assembly of claim 1 , wherein the adhesive is arranged around a perimeter of each of the grating regions.
14 . The eyepiece assembly of claim 1 , further comprising a lens positioned adjacent to the first cover layer.
15 . The eyepiece assembly of claim 1 , wherein a contact angle of water on a surface of the first cover layer, a surface of the second cover layer, or both exceeds 90°.
16 . The eyepiece assembly of claim 1 , wherein each optical waveguide comprises a nanopattern extending from a surface of the optical waveguide and configured to repel an adjacent optical waveguide.
17 . The eyepiece assembly of claim 16 , wherein the nanopattern is positioned outside a light propagating path of the eyepiece assembly.