Image projection
A diffractive structure arranged to spatially modulate light transformable by a viewing system into a target image. The diffractive structure is configured to generate a plurality of discrete light patterns. Each light pattern corresponds to a different part of the target image. The shape of each discrete light pattern substantially corresponds to the shape of an entrance aperture of the viewing system.
1 . A diffractive structure arranged to spatially modulate light transformable by a viewing system into an image, wherein the diffractive structure is configured to route light into a plurality of hologram channels, each hologram channel corresponding to a different sub-area of the image,
wherein the diffractive structure comprises a plurality of pixels;
wherein the diffractive structure is arranged to spatially modulate light in accordance with a hologram of an image;
wherein the diffractive structure is arranged to divide content of the image by angle such that a central axis of each hologram channel propagates from the diffractive structure at different respective angles;
wherein the diffractive structure is arranged such that each pixel of the diffractive structure contributes light to each of the hologram channels.
2 . A diffractive structure as claimed in claim 1 wherein each hologram channel substantially comprises spatially modulated light in accordance with a respective different sub-area of the image.
3 . A diffractive structure as claimed in claim 1 arranged to spatially modulate the phase of light.
4 . A diffractive structure as claimed in claim 1 arranged to route light through a waveguide.
5 . A diffractive structure as claimed in claim 4 wherein the waveguide is arranged for pupil expansion.
6 . A diffractive structure as claimed in claim 1 wherein a cross-sectional shape of the light pattern formable by each hologram channel substantially corresponds to the shape of an entrance aperture of the viewing system.
7 . A diffractive structure as claimed in claim 1 wherein the hologram channels are spatially separated or at least partially spatially separated.
8 . A system comprising the diffractive structure of claim 1 , a waveguide arranged to receive the spatially modulated light from the diffractive structure and a viewing system arranged to receive the spatially modulated light via the waveguide.
9 . A system as claimed in claim 8 arranged such that light of each hologram channel follows a different optical path from the diffractive structure to the viewing system.
10 . A system as claimed in claim 9 wherein the different optical paths comprise a different number of reflections within the waveguide.
11 . A system as claimed in claim 9 wherein the different optical paths are different lengths.
12 . A system as claimed in claim 9 where the different optical paths pass through the entrance aperture of the viewing system at different respective angles.
13 . A system as claimed in claim 9 wherein the waveguide is arranged so that all hologram channels are routed through the entrance aperture of the viewing system at any viewing position on a viewing plane.
14 . A system as claimed in claim 13 wherein the waveguide only routes each hologram channel via one optical path to the viewing system for each permitted viewing position.
15 . A system as claimed in claim 8 wherein at least two hologram channels of the plurality of hologram channels are partially overlapping at the entrance aperture of the viewing system.
16 . The diffractive structure of claim 1 wherein the diffractive structure is a kinoform or hologram.
17 . A method of calculating a hologram of an image, the method comprising at least one step including cropping light paths during calculation in accordance with the entrance pupil of the viewing system to form a hologram that, when illuminated, forms spatially modulated light, wherein continuous light channels of the spatially modulated light correspond with continuous regions of the image,
wherein the hologram comprises a plurality of pixels;
wherein the hologram is arranged to divide content of the image by angle such that a central axis of each hologram channel propagates from the hologram at different respective angles; and
wherein the hologram is arranged such that each pixel of the hologram contributes light to each of the hologram channels.
18 . A method of spatially modulating light to provide spatially modulated light transformable by a viewing system into an image, the method comprising:
illuminating a diffractive structure with light; and
spatially-modulating light using the diffractive structure, wherein the diffractive structure routes the spatially-modulated light into a plurality of hologram channels, each hologram channel corresponding to a different sub-area of the image,
wherein the diffractive structure comprises a plurality of pixels;
wherein the diffractive structure is spatially modulates light in accordance with a hologram of an image;
wherein the diffractive structure divides content of the image by angle such that a central axis of each hologram channel propagates from the diffractive structure at different respective angles;
wherein each pixel of the diffractive structure contributes light to each of the hologram channels.