Display system with spatial light modulator illumination for divided pupils
Illuminations systems that separate different colors into laterally displaced beams may be used to direct different color image content into an eyepiece for displaying images in the eye. Such an eyepiece may be used, for example, for an augmented reality head mounted display. Illumination systems may be provided that utilize one or more waveguides to direct light from a light source towards a spatial light modulator. Light from the spatial light modulator may be directed towards an eyepiece. Some aspects of the invention provide for light of different colors to be outcoupled at different angles from the one or more waveguides and directed along different beam paths.
1. A display device comprising:
a light source;
a waveguide disposed with respect to said light source to receive light from said light source, said waveguide including an outcoupling optical element configured to eject light out of said waveguide; and
a spatial light modulator disposed with respect to said waveguide to receive said light ejected from said waveguide and modulate said light, wherein said outcoupling optical element comprises a plurality of volume phase gratings arranged in a stack, and wherein the stack is positioned on a first surface of the waveguide and is arranged to receive the light from the light source, wherein each volume phase grating of the plurality of volume phase gratings is configured to reflect the light received from the light source toward the first surface of the waveguide at a different respective angle of diffraction such that the light ejected from the waveguide is outcoupled to different locations corresponding to the different respective angles of diffraction.
2. The display device of claim 1 , wherein each volume phase grating in the plurality of volume phase gratings is configured to diffract light having a different respective wavelength.
3. The display device of claim 1 , wherein each volume phase grating in the plurality of volume phase gratings is configured to diffract light of a same color into a different respective angle of diffraction.
4. The display device of claim 1 , wherein a coupling efficiency of the outcoupling optical element exhibits a gradient with distance away from the light source.
5. The display device of claim 4 , wherein the coupling efficiency of the outcoupling optical element is lower closer to the light source and higher farther from the light source.
6. The display device of claim 1 , wherein the waveguide has a wedge-shape.
7. The display device of claim 1 , wherein the waveguide has a curved-shape.
8. A display device comprising:
a light source having a first spectral distribution;
a waveguide disposed with respect to said light source to receive light from said light source, said waveguide including an outcoupling optical element comprising a liquid crystal and configured to eject light out of said waveguide;
a spatial light modulator disposed with respect to said waveguide to receive said light ejected from said waveguide and modulate said light;
a first optical retarder arranged between the liquid crystal and the spatial light modulator, wherein the first optical retarder is disposed on a first side of the waveguide between the waveguide and the spatial light modulator, and wherein the first optical retarder converts circularly polarized light diffracted from the liquid crystal into linear polarized light; and
a second optical retarder, wherein the second optical retarder is disposed on a second side of the waveguide that is opposite to the first side of the waveguide, and wherein the second optical retarder converts circular polarized light into linear polarized light with a linear polarization different than that of the first optical retarder.
9. The display device of claim 8 , wherein the liquid crystal is configured to diffract circularly polarized light and the spatial light modulator is configured to modulate linear polarized light.
10. The display device of claim 8 , wherein the first optical retarder is a quarter-wave retarder.
11. The display device of claim 8 , wherein the liquid crystal has a gradient in coupling efficiency.
12. The display device of claim 11 , wherein the liquid crystal is configured to have a high diffractive efficiency further away from the light source and a lower diffractive efficiency closer to the light source.
13. The display device of claim 8 , wherein the liquid crystal comprises a stack of cholesteric liquid crystal diffractive elements, wherein each cholesteric liquid crystal diffractive element of the stack of cholesteric liquid crystal diffractive elements is configured to diffract a different respective color.
14. The display device of claim 8 , wherein the waveguide has a wedge-shape.
15. The display device of claim 8 , wherein the waveguide has a curved-shape.
16. A display device for a head mounted display comprising:
a waveguide based image source comprising:
one or more light emitters configured to emit light; and
one or more waveguides disposed with respect to said one or more light emitters to receive light from said one or more light emitters such that light is guided within said one or more waveguides via total internal reflection, said one or more waveguides configured to eject light out of said waveguides;
a spatial light modulator disposed with respect to one or more waveguides to receive said light ejected from said one or more waveguides and modulate said light, wherein said one or more light emitters are configured to emit light having a spectral distribution that includes spectral components corresponding to first and second colors, and wherein said waveguide based image source is configured such that said light of said first and second colors after being modulated by said spatial light modulator is directed along said respective first and second paths and is incident on respective first and second spatial locations a distance from said one or more waveguides and said spatial light modulator; and
an eyepiece element comprising a waveguide based light distribution system comprising:
a first waveguide having associated therewith an in-coupling optical element disposed with respect to one or more first waveguides and said first path to receive light from said one or more waveguides after being modulated by said spatial light modulator; and
a second waveguide having associated therewith an in-coupling optical element disposed with respect to said one or more waveguides and said second path to receive light from said one or more waveguides after being modulated by said spatial light modulator, wherein said in-coupling optical elements associated with said first and second waveguides, respectively, are located at said first and second spatial locations along said first and second paths respectively to receive said light of said first and second colors, respectively.