Waveguides having integral spacers and related systems and methods
A head-mounted, near-eye display system comprises a stack of waveguides having integral spacers separating the waveguides. The waveguides may each include diffractive optical elements that are formed simultaneously with the spacers by imprinting or casting. The spacers are disposed on one or more major surfaces of the waveguides and define a distance between immediately adjacent waveguides. Adjacent waveguides may be bonded using adhesives on the spacers. The spacers may fit within indentations of overlying waveguides. In some cases, the spacers may form one or more walls of material substantially around a perimeter of an associated waveguide. Vent holes may be provided in the walls to allow gas flow into and out from an interior volume defined by the spacers. Debris trapping structures may be provided between two walls of spacers to trap and prevent debris from entering into the interior volume.
1. A display system comprising a stack of waveguides, the stack of waveguides comprising:
a first waveguide comprising an optically transmissive body, a first major surface, and a spacer integral with the optically transmissive body, the spacer 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 spacer; and
an adhesive provided on a top surface of the spacer, the adhesive attaching the spacer to the second major surface of the second waveguide,
wherein the adhesive has an as-deposited viscosity of 10 mPa·s to 100 mPa·s,
wherein the adhesive constitutes a first adhesive,
wherein the stack of waveguides further comprises a second adhesive forming an adhesive mass extending between and attaching the first major surface of the first waveguide to the second major surface of the second waveguide,
wherein the first adhesive and the second adhesive have different viscosities, and
wherein the second adhesive has an as-deposited viscosity of 10,000 mPa·s to 50,000 mPa·s.
2. The display system of claim 1 , wherein the spacer extends along a perimeter of the first waveguide.
3. The display system of claim 1 , wherein the spacer defines an edge of the stack.
4. The display system of claim 1 , wherein the second adhesive is located peripherally to the spacer on the first major surface of the first waveguide.
5. The display system of claim 1 , wherein the first waveguide further comprises one or more diffractive optical elements in an area of the first major surface interior of the spacer.
6. The display system of claim 5 , wherein the first major surface of the first waveguide further comprises an adhesive-trapping depression between the one or more diffractive optical elements and the adhesive.
7. The display system of claim 1 , wherein the adhesive is disposed on the top surface and on lateral sides of the spacer.
8. The display system of claim 1 , wherein the first waveguide comprises a plurality of spacers.
9. The display system of claim 1 , wherein one or more surfaces contacting the adhesive are rough.
10. The display system of claim 9 , wherein the one or more surfaces are nanotextured.
11. The display system of claim 9 , further comprising an adhesive flow barrier extending along two or more sides of the top surface, the adhesive flow barrier defining a central volume occupied by the adhesive.
12. The display system of claim 1 , wherein the spacer comprises one or more vent holes extending laterally through the spacer.
13. The display system of claim 12 , wherein the first waveguide comprises a plurality of spacers, wherein each spacer comprises one or more vent holes.
14. The display system of claim 13 , wherein pairs of spacers of spacers of the plurality of spacers are laterally elongated alongside one another, wherein the stack of waveguides further comprises one or more debris trapping structures located in a volume between adjacent pairs spacers of the plurality of spacers.
15. The display system of claim 1 , wherein the spacer is located in an interior area of the first major surface of the first waveguide.
16. The display system of claim 15 , wherein the spacer comprises a single point contact spacer having a maximum transverse cross-sectional dimension of 500 μm or less.
17. The display system of claim 1 , wherein the second major surface of the second waveguide comprises an indentation accommodating the spacer in the indentation.
18. The display system of claim 17 , wherein the stack of waveguides comprises a plurality of waveguides, wherein two or more waveguides of the plurality of waveguides comprise a spacer and an indentation, wherein the indentations accommodate spacers of underlying waveguides.
19. The display system of claim 1 , wherein the spacer comprises a shape selected from the group consisting of rectangular prism, rectangular pyramid, triangular prism, triangular pyramid, cylinder, and cone.
20. The display system of claim 1 , wherein the adhesive comprises a light absorber.
21. The display system of claim 20 , wherein the adhesive is doped with a black colorant.
22. The display system of claim 1 , wherein the first and the second waveguide are separated by an air gap having a size defined by the spacer and adhesive.
23. The display system of claim 1 , wherein the adhesive has a refractive index greater than 1.65.
24. The display system of claim 1 , wherein the first and second waveguides each comprise:
in-coupling optical elements configured to in-couple incident image light; and
out-coupling optical elements configured to out-couple the in-coupled image light.
25. The display system of claim 24 , further comprising a light projector system configured to project the image light to the in-coupling optical elements.
26. The display system of claim 1 , wherein the spacer comprises a light absorbing material.
27. A display system comprising a stack of waveguides, the stack of waveguides comprising:
a first waveguide comprising an optically transmissive body, a first major surface, and a spacer integral with the optically transmissive body, the spacer 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 spacer; and
an adhesive provided on a top surface of the spacer, the adhesive attaching the spacer to the second major surface of the second waveguide,
wherein the adhesive has an as-deposited viscosity of 10 mPa·s to 100 mPa·s,
wherein the first waveguide further comprises one or more diffractive optical elements in an area of the first major surface interior of the spacer, and
wherein the first major surface of the first waveguide further comprises an adhesive-trapping depression between the one or more diffractive optical elements and the adhesive.
28. The display system of claim 27 , wherein the adhesive is disposed on the top surface and on lateral sides of the spacer.
29. The display system of claim 27 , further comprising an adhesive flow barrier extending along two or more sides of the top surface, the adhesive flow barrier defining a central volume occupied by the adhesive.
30. The display system of claim 27 , wherein the spacer comprises one or more vent holes extending laterally through the spacer.
31. The display system of claim 27 , wherein the spacer is located in an interior area of the first major surface of the first waveguide.
32. The display system of claim 27 , wherein the second major surface of the second waveguide comprises an indentation accommodating the spacer in the indentation.
33. The display system of claim 27 , wherein the adhesive comprises a light absorber.
34. A display system comprising a stack of waveguides, the stack of waveguides comprising:
a first waveguide comprising an optically transmissive body, a first major surface, and a spacer integral with the optically transmissive body, the spacer 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 spacer;
an adhesive provided on a top surface of the spacer, the adhesive attaching the spacer to the second major surface of the second waveguide; and
an adhesive flow barrier extending along two or more sides of the top surface, the adhesive flow barrier defining a central volume occupied by the adhesive,
wherein the adhesive has an as-deposited viscosity of 10 mPa·s to 100 mPa·s,
wherein one or more surfaces contacting the adhesive are rough.
35. The display system of claim 34 , wherein the adhesive is disposed on the top surface and on lateral sides of the spacer.
36. The display system of claim 34 , further comprising an adhesive flow barrier extending along two or more sides of the top surface, the adhesive flow barrier defining a central volume occupied by the adhesive.
37. The display system of claim 34 , wherein the spacer comprises one or more vent holes extending laterally through the spacer.
38. The display system of claim 34 , wherein the spacer is located in an interior area of the first major surface of the first waveguide.
39. The display system of claim 34 , wherein the second major surface of the second waveguide comprises an indentation accommodating the spacer in the indentation.
40. The display system of claim 34 , wherein the adhesive comprises a light absorber.
41. A display system comprising a stack of waveguides, the stack of waveguides comprising:
a first waveguide comprising an optically transmissive body, a first major surface, and a spacer integral with the optically transmissive body, the spacer 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 spacer; and
an adhesive provided on a top surface of the spacer, the adhesive attaching the spacer to the second major surface of the second waveguide,
wherein the adhesive has an as-deposited viscosity of 10 mPa·s to 100 mPa·s,
wherein the spacer comprises one or more vent holes extending laterally through the spacer.
42. The display system of claim 41 , wherein the first waveguide comprises a plurality of spacers, wherein each spacer comprises one or more vent holes.
43. The display system of claim 42 , wherein pairs of spacers of spacers of the plurality of spacers are laterally elongated alongside one another, wherein the stack of waveguides further comprises one or more debris trapping structures located in a volume between adjacent pairs spacers of the plurality of spacers.
44. The display system of claim 41 , wherein the adhesive is disposed on the top surface and on lateral sides of the spacer.
45. The display system of claim 41 , further comprising an adhesive flow barrier extending along two or more sides of the top surface, the adhesive flow barrier defining a central volume occupied by the adhesive.
46. The display system of claim 41 , wherein the spacer is located in an interior area of the first major surface of the first waveguide.
47. The display system of claim 41 , wherein the second major surface of the second waveguide comprises an indentation accommodating the spacer in the indentation.
48. The display system of claim 41 , wherein the adhesive comprises a light absorber.