Device for augmented reality or virtual reality display

An augmented reality or virtual reality device comprising:

• a projector configured to provide augmented reality or virtual reality images;
• and
• an optical structure comprising:
• a waveguide;
• an output diffractive optical structure arranged parallel to a surface of the waveguide and configured to receive light propagating within the waveguide in an input direction,
• the output diffractive optical structure comprising two portions, each portion comprising a diffraction grating having a first diffractive optical element and a second diffractive optical element arranged according to non-parallel grating vectors;
• the first diffractive optical element of each portion being configured to receive light along the input direction and couple:
• a first proportion of the light towards the second diffractive optical element which can then act as an output diffractive optical element, providing outcoupled orders towards a viewer;
• and
• a second proportion of the light towards the other portion of the output diffractive optical structure;
• the second diffractive optical element of each portion being configured to receive light along the input direction and couple:
• a third proportion of the light towards the first diffractive optical element which can then act as an output diffractive optical element, providing outcoupled orders towards a viewer;
• and
• a fourth proportion of the light away from the other portion of the output diffractive optical structure.

A waveguide, comprising:

• an output diffractive optical structure arranged parallel to a surface of the waveguide and configured to receive light propagating within the waveguide in an input direction,
• the output diffractive optical structure comprising two portions, each portion comprising a diffraction grating having a first diffractive optical element and a second diffractive optical element arranged according to non-parallel grating vectors;
• the first diffractive optical element of each portion being configured to receive light along the input direction and couple:
• a first proportion of the light towards the second diffractive optical element which can then act as an output diffractive optical element, providing outcoupled orders towards a viewer;
• and
• a second proportion of the light towards the other portion of the output diffractive optical structure;
• the second diffractive optical element of each portion being configured to receive light along the input direction and couple:
• a third proportion of the light towards the first diffractive optical element which can then act as an output diffractive optical element, providing outcoupled orders towards a viewer;
• and
• a fourth proportion of the light away from the other portion of the output diffractive optical structure.