Optical: systems and elements – Holographic system or element – For producing or reconstructing images from multiple holograms
Patent
1996-12-05
2000-12-05
Spyrou, Cassandra
Optical: systems and elements
Holographic system or element
For producing or reconstructing images from multiple holograms
359 24, 359 28, 359 15, G02B 532, G03H 126, G03H 128, G03H 102
Patent
active
061574740
DESCRIPTION:
BRIEF SUMMARY
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a display device incorporating a holographic optical element.
In our earlier application WO93/02372 we describe a display device incorporating a holographic optical element. Light incident on the holographic optical element is directed to a single viewing zone. By moving the source of the light, the position of the viewing zone can be moved. Temporally alternating left and right images are projected on the screen from alternating positions whereby the images are viewable one after the other in respective left and right hand viewing zones.
According to a first aspect of the present invention, we provide a display device comprising a holographic optical element having at least two sets of hologram regions, the region(s) of the first set being interleaved or overlapping with adjacent region(s) of the second set(s) and being constructed such that light incident on each set of regions is diffracted so as to construct a respective one or more of a plurality of real or virtual images of a diffuse light source; and image generating means comprising a plurality of image elements; wherein the holographic element and its hologram regions are disposed and designed such that light diffracted by the first set of hologram regions passes through a corresponding first set of image elements and such that light diffracted by the second set of hologram regions passes through a corresponding second set of image elements.
According to a second aspect of the present invention, we provide a display device comprising a holographic optical element having at least two sets of hologram regions, the region(s) of the first set being interleaved or overlapping with adjacent region(s) of the second set(s) and being constructed such that light incident on each set of regions is diffracted so as to construct a respective one or more of a plurality of real or virtual images of a diffuse light source; and image generating means comprising a plurality of image elements; wherein the holographic optical element and its hologram regions are disposed and designed such that light having passed through a first set of image elements of the image generating means is diffracted by the first set of hologram regions and such that light having passed through a second set of image elements of the image generating means is diffracted by the second set of hologram regions.
Each set may comprise a single region which extends across a large proportion of the holographic optical element. Typically however, each set of regions comprises an array of regions.
Typically the regions making up an array are laterally offset from each other (e.g. vertically and/or horizontally).
Each region in an array is typically spaced from and does not overlap with adjacent regions in the array, although adjacent regions in the same array may overlap.
Also, each set of regions is typically laterally offset from the other set(s) of regions. The regions within an array may overlap with regions of other arrays. Typically however, the regions of each array do not overlap with regions of other arrays.
The at least two sets of regions may make up a lateral array of vertical or horizontal stripes, or a two dimensional array such as a honeycomb.
In a preferable embodiment, the holographic optical element comprises two interleaved sets of regions.
Typically the holographic optical element is constructed such that each set of regions comprises a holographic recording of one or more diffuse light sources.
By making a recording of the same light source, or a number of different light sources in a plurality of different positions with respect to the holographic optical element, the light incident on the holographic optical element is directed to a position corresponding with the position(s) of the diffuse light source(s). Put another way, when each of the sets of regions is illuminated with light, the diffracted light forms an image of the one or more diffuse light sources. Typically the image is a real image although it may also
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Orr Edwina Margaret
Trayner David John
Richmond Holographic Research Limited
Spyrou Cassandra
Treas Jared
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