Patent attributes
An optical waveguide is provided having at least first and second diffraction regions, the first diffraction region being arranged to diffract image-bearing light propagating along the waveguide so as to expand it in a first dimension and to turn the image-bearing light towards the second diffraction region, the second diffraction region being arranged to diffract the image-bearing light so as to expand it in a second dimension and to release it from the waveguide as a visible image. The first diffraction region is formed by first diffraction grating embedded within the waveguide, arranged to present a substantially similar profile to the image-bearing light when incident upon the grating from a given angle above or below the grating such that the polarization of the image bearing light is rotated by substantially similar amounts, but in opposite directions, by successive interactions with the first diffraction region. This enables image-bearing light, emitted from the waveguide, to present an image of substantially uniform intensity.
