Abstract: An augmented reality display is disclosed. A colour projector (2) emits an image in a narrow beam comprising three primary colours: red, green and blue. A pair of waveguides (4, 6) is provided in the path of the projected beam. A first input grating (8) receives light from the projector (2) and diffracts the received light so that diffracted wavelengths of the light in first and second primary colours are coupled into the first waveguide (6), and so that diffracted wavelengths of the light in second and third primary colours are coupled out of the first waveguide in a direction towards the second waveguide (4). A second input diffraction grating (10) receives light coupled out of the first waveguide (6) and diffracts the second and third primary colours so that they are coupled into the second waveguide (4).

Abstract: A display system is disclosed for use in an augmented reality display (30), the system comprises a waveguide (32) having a front surface and a rear surface. A front input projector (34) projects polychromatic light through a front surface, and a back input projector (36) projects polychromatic light through the rear surface. Input light impinges on an input grating (38) on a rear surface of the waveguide (32), and light travels through the waveguide by total internal reflection. An output grating (40) is provided for coupling light out of the waveguide. A plurality of front and back input projectors (34, 36) are provided in a staggered configuration along the width of the waveguide (32) and respective edges of adjacent front and back input projectors are aligned along the width of the waveguide to permit a continuous projection of light.

Abstract: An optical device is disclosed for expanding input light in two dimensions in an augmented reality display. The device comprises a waveguide (12) and three linear diffraction grat-ings H0, H1, H2. An incident beam from a projector illuminates an input grating H0 with polychromatic light, and the light is coupled into the waveguide (12). The other two gratings H1, H2 are overlaid on top of one another. Light can be diffracted by one grating H1 into a first diffracted order and towards the other grating H2 which can couple the light out of the waveguide (12) towards a viewer. In another arrangement the crossed gratings H1, H2 may be replaced by a photonic crystal (19) having a regular array of pillars (20) which create a number effective diffraction gratings.

Abstract: A display system is disclosed for use in an augmented reality display (30), the system comprises a waveguide (32) having a front surface and a rear surface. A front input projector (34) projects polychromatic light through a front surface, and a back input projector (36) projects polychro matic light through the rear surface. Input light impinges on an input grating (38) on a rear surface of the waveguide (32), and light travels through the waveguide by total internal reflection. An output grating (40) is provided for coupling light out of the waveguide. A plurality of front and back input projectors (34, 36) are provided in a staggered configuration along the width of the waveguide (32) and respective edges of adjacent front and back input projectors are aligned along the width of the waveguide to permit a continuous projection of light.