Environmentally isolated waveguide display
A waveguide display is provided comprising: an input image generator providing image light projected over a field of view; a waveguide having first and second external surfaces; and at least one grating optically coupled to the waveguide for extracting light towards a viewer. The waveguide has a lateral refractive index variation between said external surfaces that prevents any ray propagated within the waveguide from optically interacting with at least one of the external surfaces.
1. A waveguide display, comprising:
a waveguide structure having external surfaces in contact with a low refractive index medium, wherein said wavequide structure is curved;
a source of image modulated light projected over a field of view;
an input coupler for directing said light into at least one optical path in said waveguide structure; and
at least one grating for extracting light from said waveguide structure for viewing;
wherein at least a portion of said waveguide structure has a lateral refractive index variation between said external surfaces that prevents rays propagating within said waveguide from optically interacting with at least one of said external surfaces, and
wherein at least one intermediate image surface is formed within said waveguide.
2. The waveguide display of claim 1 , wherein said light extracted from said waveguide structure for viewing forms an image surface disposed at an angle to said intermediate image surface.
3. The waveguide display of claim 1 , wherein said light extracted from said waveguide structure for viewing forms an image surface that is substantially orthogonal to said intermediate image surface.
4. The waveguide display of claim 1 , wherein said light extracted from said waveguide structure for viewing forms an image surface disposed an angle in the range from 0 degrees to 90 degrees to said intermediate image surface.
5. The waveguide display of claim 1 , wherein said at least one grating is substantially parallel to a total internal reflection surface of said waveguide structure.
6. The waveguide display of claim 1 , wherein said intermediate image surface is substantially orthogonal to a total internal reflection surface of said waveguide structure.
7. The waveguide display of claim 1 , wherein said waveguide structure further comprises at least one selected from the group of:
a GRIN medium for providing at least part of said lateral refractive index variation;
a GRIN medium at least partially enclosing said grating;
a GRIN medium optically coupled to a waveguide portion supporting said grating;
a GRIN medium optically coupled to a waveguide portion in which light propagates under total internal reflection between said external surfaces;
a homogeneous refractive index material layer in contact with air;
a homogeneous refractive index material layer in contact with said grating;
a homogeneous refractive index material layer sandwiched by layers of lower refractive index;
a homogeneous refractive index material layer sandwiched by air and a layer of higher refractive index;
a homogeneous refractive index material layer of refractive index greater than the average refractive index of said grating;
a homogeneous refractive index material layer of refractive index substantially the same as the average refractive index of said grating;
a homogenous refractive index material layer of refractive index less than the average refractive index of said grating;
a surface of said grating in contact with air;
a beam splitter layer; and
at least one additional grating.
8. The waveguide display of claim 7 , wherein total internal reflection can occur between the outermost surfaces of a set of layers selected from said group.
9. The waveguide display of claim 1 , wherein said at least one grating is sandwiched by transparent substrates.
10. The waveguide display of claim 1 , wherein said at least one grating is one of a Bragg grating, a surface relief grating, a switchable Bragg grating recorded in a HPDLC material, a uniform modulation HPDLC material or a reverse mode HPDLC material.
11. The waveguide display of claim 1 , wherein said low refractive index medium is air.
12. The waveguide display of claim 1 , wherein said input coupler is a grating.
13. The waveguide display of claim 1 , wherein said image modulated light is collimated prior to being coupled into said waveguide structure.
14. The waveguide display of claim 1 , wherein said waveguide structure comprises planar waveguide elements abutting end to end.
15. The waveguide display of claim 1 , wherein said waveguide structure is configured to provide one of a heads-up display, a head mounted display, or a light field display.
16. A wavequide display, comprising:
a waveguide structure having external surfaces in contact with a low refractive index medium;
a source of image modulated light projected over a field of view;
an input coupler for directing said light into at least one optical path in said waveguide structure; and
at least one grating for extracting light from said waveguide structure for viewing;
wherein at least a portion of said waveguide structure has a lateral refractive index variation between said external surfaces that prevents rays propagating within said waveguide from optically interacting with at least one of said external surfaces,
wherein at least one intermediate image surface is formed within said waveguide, and
wherein said at least one grating is substantially orthogonal to said image surface.
17. A waveguide display, comprising:
a waveguide structure having external surfaces in contact with a low refractive index medium;
a source of image modulated light projected over a field of view;
an input coupler for directing said light into at least one optical path in said waveguide structure; and
at least one grating for extracting light from said waveguide structure for viewing;
wherein at least a portion of said waveguide structure has a lateral refractive index variation between said external surfaces that prevents rays propagating within said waveguide from optically interacting with at least one of said external surfaces,
wherein at least one intermediate image surface is formed within said waveguide, and
wherein said at least one grating is substantially orthogonal to a total internal reflection surface of said waveguide structure.
18. A waveguide display, comprising:
a waveguide structure having external surfaces in contact with a low refractive index medium;
a source of image modulated light projected over a field of view;
an input coupler for directing said light into at least one optical path in said waveguide structure; and
at least one grating for extracting light from said waveguide structure for viewing;
wherein at least a portion of said waveguide structure has a lateral refractive index variation between said external surfaces that prevents rays propagating within said waveguide from optically interacting with at least one of said external surfaces,
wherein at least one intermediate image surface is formed within said waveguide, and
wherein said at least one grating has spatially varying refractive index modulation.
19. A waveguide display, comprising:
a waveguide structure having external surfaces in contact with a low refractive index medium;
a source of image modulated light projected over a field of view;
an input coupler for directing said light into at least one optical path in said waveguide structure; and
at least one grating for extracting light from said waveguide structure for viewing;
wherein at least a portion of said waveguide structure has a lateral refractive index variation between said external surfaces that prevents rays propagating within said waveguide from optically interacting with at least one of said external surfaces,
wherein at least one intermediate image surface is formed within said waveguide, and
wherein said waveguide structure further comprises at least one grating selected from the group of: a rolled K-vector grating; a grating with spatially varying refractive index modulation; and gratings configured for providing beam expansion in at least one of two orthogonal directions.