Display for augmented reality or virtual reality

1. An augmented reality or virtual reality display device, comprising:

a first projector and a second projector;

at least one waveguide assembly, comprising at least one waveguide;

a first input diffractive optical element positioned in or on the at least one waveguide assembly configured to receive light from the first projector and to couple the light into the at least one waveguide;

a second input diffractive optical element positioned in or on the at least one waveguide assembly configured to receive light from the second projector and to couple the light into the at least one waveguide;

an output diffractive optical element positioned in or on the at least one waveguide assembly configured to couple light out of the at least one waveguide towards a notional viewing position;

wherein the first projector is configured to provide light to the first input diffractive optical element in a direction that is at a first angle to a waveguide normal vector, and the second projector is configured to provide light to the second input diffractive optical element in a direction that is at a second angle to the waveguide normal vector;

wherein the output diffractive optical element is configured to couple light out of the at least one waveguide in a first range of angles for light from the first projector and in a second range of angles for light from the second projector, wherein the first range of angles and the second range of angles are different but are partially overlapping; and

wherein the first and second angles are angled respectively away from the output diffractive optical element.

2. The display device of claim 1 , wherein the at least one waveguide assembly comprises a first waveguide assembly and a second waveguide assembly, respectively comprising at least one waveguide, and wherein the first input diffractive optical element is configured to couple light from the first projector into the at least one waveguide in the first waveguide assembly and the second input diffractive optical element is configured to couple light from the second projector into the at least one waveguide in the second waveguide assembly.

3. The display device of claim 2 , wherein the first waveguide assembly is a stack of waveguides and wherein there is a plurality of first input diffractive optical elements respectively positioned in or on each waveguide in the stack of waveguides, and wherein the first projector is configured to provide a plurality of wavelengths of light which are coupled by the plurality of first input diffractive optical elements into the stack of waveguides.

4. The display device of claim 3 , wherein the second waveguide assembly is a stack of waveguides and wherein there is a plurality of second input diffractive optical elements respectively positioned in or on each waveguide in the stack of waveguides, and wherein the second projector is configured to provide a plurality of wavelengths of light which are coupled by the plurality of second input diffractive optical elements into the stack of waveguides.

5. The display device of claim 1 , comprising a third projector configured to provide light to a third input diffractive optical element in a direction that is at a third angle to a waveguide normal vector, and wherein the output diffractive optical element is configured to couple light out of the at least one waveguide in a third range of angles for light from the third projector, wherein the second range of angles and the third range of angles are partially overlapping.

6. The display device of claim 2 , wherein the first and second projectors are positioned so that they provide light directly to first and second waveguide assemblies.

7. The display device of claim 6 , wherein the first and second input diffractive optical elements are offset from one another in the first and second waveguide assemblies so that light can be coupled directly from the first and second projectors to the first and second input diffractive optical elements respectively.

8. The display device of claim 1 , wherein the first and second input diffractive optical elements are positioned in or on the at least one waveguide assembly on either side of the output diffractive optical element.

9. The display device of claim 8 , comprising a periscope for coupling light from the first projector to the first input diffractive optical element so that the first projector and the second projector can be positioned on the same side of the output diffractive optical element.

10. The display device of claim 8 , wherein the first and second input diffractive optical elements are positioned above and below the output diffractive optical element from the perspective of a user.

11. The display device of claim 8 , wherein the first and second input diffractive optical elements are positioned to the left and right of the output diffractive optical element from the perspective of a user.

12. The display device of claim 11 , further comprising a third projector and a fourth projector, and a third input diffractive optical element and a fourth input diffractive optical element, wherein the third and fourth input diffractive optical elements are positioned above and below the output diffractive optical element from the perspective of a user.

13. The display device of claim 1 , further comprising a prism positioned between the first projector and the at least one waveguide assembly to reduce the spread of angles of light rays from the first projector where they encounter the at least one waveguide assembly.

14. The display device of claim 9 , wherein the first and second input diffractive optical elements are positioned above and below the output diffractive optical element from the perspective of a user.

15. The display device of claim 9 , wherein the first and second input diffractive optical elements are positioned to the left and right of the output diffractive optical element from the perspective of a user.

16. A method for projecting light via an augmented reality or virtual reality display device, comprising:

projecting light from a first projector;

directing the light from the first projector toward a first input diffractive optical element positioned in or on at least one waveguide assembly having at least one waveguide in a direction that is at a first angle to a waveguide normal vector;

coupling the light from the first projector into at the least one waveguide;

projecting light from a second projector;

directing the light from the second projector toward a second input diffractive optical element positioned in or on the at least one waveguide assembly in a direction that is at a second angle to the waveguide normal vector;

coupling the light from the second projector into the at least one waveguide; and

coupling light out of the at least one waveguide towards a notional viewing position via an output diffractive optical element positioned in or on the at least one waveguide assembly;

wherein the output diffractive optical element is configured to couple light out of the at least one waveguide in a first range of angles for light from the first projector and in a second range of angles for light from the second projector, wherein the first range of angles and the second range of angles are different but are partially overlapping; and

wherein the first and second angles are angled respectively away from the output diffractive optical element.

17. The method of claim 16 , wherein the at least one waveguide assembly comprises a first waveguide assembly and a second waveguide assembly, respectively comprising at least one waveguide, and wherein the first input diffractive optical element is configured to couple light from the first projector into the at least one waveguide in the first waveguide assembly and the second input diffractive optical element is configured to couple light from the second projector into the at least one waveguide in the second waveguide assembly.

18. The method of claim 17 , wherein the first waveguide assembly is a stack of waveguides and wherein there is a plurality of first input diffractive optical elements respectively positioned in or on each waveguide in the stack of waveguides, and wherein the first projector is configured to provide a plurality of wavelengths of light which are coupled by the plurality of first input diffractive optical elements into the stack of waveguides.

19. The method of claim 18 , wherein the second waveguide assembly is a stack of waveguides and wherein there is a plurality of second input diffractive optical elements respectively positioned in or on each waveguide in the stack of waveguides, and wherein the second projector is configured to provide a plurality of wavelengths of light which are coupled by the plurality of second input diffractive optical elements into the stack of waveguides.

20. The method of claim 16 , further comprising:

projecting light from a third projector; and

directing the light from the third projector to a third input diffractive optical element in a direction that is at a third angle to a waveguide normal vector;

wherein the output diffractive optical element is configured to couple light out of the at least one waveguide in a third range of angles for light from the third projector, wherein the second range of angles and the third range of angles are partially overlapping.