Transparent Waveguide Display
One embodiment provides an apparatus for displaying an image comprising: a first optical substrate comprising at least one waveguide layer configured to propagate light in a first direction, wherein the at least one waveguide layer of the first optical substrate comprises at least one grating lamina configured to extract the light from the first substrate along the first direction; and a second optical substrate comprising at least one waveguide layer configured to propagate the light in a second direction, wherein the at least one waveguide layer of the second optical substrate comprises at least one grating lamina configured to extract light from the second substrate along the second direction; wherein the at least one grating lamina of at least one of the first and second optical substrates comprises an SBG in a passive mode.
1 . A waveguide device comprising:
an input light;
a waveguide substrate comprising an input grating and an output grating, wherein at least one of the input grating and the output grating provide rolled k-vectors across the waveguide substrate,
wherein the input grating is configured to provide beam expansion of the input light within the waveguide substrate, and
wherein the output grating is configured to provide beam extraction of the light out of the waveguide substrate.
2 . The waveguide device of claim 1 , wherein an orientation of the rolled k-vectors of at least one of the input grating and the output grating has a spatial variation across the waveguide substrate.
3 . The waveguide device of claim 1 , wherein the input grating and the output grating are in a single grating layer.
4 . The waveguide device of claim 1 , wherein the input grating is configured to couple the input light into the waveguide substrate.
5 . The waveguide device of claim 1 , wherein the input grating directs the light into a total internal reflection (TIR) path within the waveguide substrate.
6 . The waveguide device of claim 5 , wherein an angular bandwidth of the TIR path has a spatial variation across at least one of the input grating and the output grating.
7 . The waveguide device of claim 1 , wherein at least one of the input grating and the output grating comprises a phase separated holographic polymer-dispersed liquid crystals (HPDLC) mixture, wherein the phase separated HPDLC comprises liquid crystal rich regions and liquid crystal poor regions.
8 . The waveguide device of claim 7 , wherein at least one of the input grating and the output grating is a surface relief grating.
9 . The waveguide device of claim 8 , wherein the input grating and the output grating have an equal surface grating pitch.
10 . The waveguide device of claim 1 , wherein the output grating provides exit pupil expansion of the extracted light.
11 . The waveguide device of claim 10 , wherein the exit pupil expansion is orthogonal to the waveguide substrate.
12 . The waveguide device of claim 1 , further comprising a pupil projector comprising:
a projector configured to produce the input light; and
a lens configured to collimate the input light into a collimated ray bundle,
wherein the input grating couples the collimated ray bundle into the waveguide substrate.
13 . The waveguide device of claim 12 , wherein the input grating directs each ray bundle into a TIR path within the waveguide substrate.
14 . The waveguide device of claim 1 , wherein the input light is image modulated.
15 . The waveguide device of claim 1 , wherein the rolled k-vectors are provided by a plurality of discrete grating elements each having a unique k-vector.
16 . The waveguide device of claim 15 , wherein the plurality of discrete grating elements are disposed in a single layer.