| 摘要 |
<p>An optical waveguide (30) 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 ii 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 (14) 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.</p> |
