Patent attributes
The present invention provides a projection display, for displaying an image to a viewer. An image-providing light source device is arranged to inject an input pupil of multi-spectral image bearing light into a waveguide assembly. The waveguide assembly comprises first and second diffraction regions arranged respectively for expanding the input pupil in first and second generally orthogonal dimensions and outputting an exit pupil expanded in the first and second dimensions from the waveguide assembly. The diffractive regions of the waveguide assembly are matched to cause zero or substantially zero net chromatic aberration. A combiner is arranged to direct the exit pupil towards the viewer for viewing an image and to transmit light from a real world scene through the combiner so that the image overlays the light from the real world scene.
