# US 11,307,534 B2 · Holographic projector > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,307,534 B2 - Document ID: US11307534B2 - Status: Granted - Kind: B2 - Application number: 16/603,531 - Filed: 2017-10-27 - Published: 2020-01-30 - Granted: 2022-04-19 - Earliest claimed: 2017-04-07 - Assignees: Dualitas Ltd - Applicants: Dualitas Ltd. - Inventors: Jamieson Christmas - Web page: https://patentgrep.com/patent/US11307534B2 ## CPC - G03H 1/2294: {Addressing the hologram to an active spatial light modulator} - G03H 1/2205: {using downstream optical component} - G03H 2001/0816: {Iterative algorithms} - G03H 2001/2215: {Plane screen} - G03H 2001/2231: {Reflection reconstruction} - G03H 2225/10: Shape or geometry - G03H 2225/22: Electrically addressed SLM [EA-SLM] - G03H: HOLOGRAPHIC PROCESSES OR APPARATUS (holograms, e.g. point holograms, used as ordinary optical elements G02B5/32; producing stereoscopic or other three-dimensional effects G02B30/00; diffraction-grating systems G02B27/44; systems using moiré fringes G02B27/60; optical logic elements G02F3/00; stereo-photography G03B35/00; photosensitive materials or processes for photographic purposes G03C; {stereo-photographic or similar processes G03C9/00}; apparatus for processing exposed photographic materials G03D; analogue computers performing mathematical operations with the aid of optical elements G06E3/00; authentication by radiation, of concealed information carried by holograms or diffraction gratings G06K19/16; holographic storage G11B7/0065, G11C13/04; {stereoscopic or other three dimensional effects in television systems H04N13/00}) ## Abstract There is provided a holographic projection system arranged to project light to a rectangular replay field. The holographic projection system comprises: a spatial light modulator, comprising an array of pixels, arranged to receive a computer-generated hologram and output spatially-modulated light forming a holographic reconstruction at the rectangular replay field, wherein each pixel is rectangular; and a light source arranged to illuminate the plurality of pixels to form the spatially-modulated light forming a holographic reconstruction at the replay field, wherein the rectangular replay field is spatially separated from the spatial light modulator and the aspect ratio of the rectangular replay field is substantially equal to the aspect ratio of each pixel but orthogonally orientated. ## Claims ### Claim 1 A holographic projection system arranged to project light to a rectangular replay field having an aspect ratio, wherein the holographic projection system comprises: a spatial light modulator, comprising an array of individually addressable pixels, arranged to receive a computer-generated hologram and output spatially-modulated light forming a holographic reconstruction at the rectangular replay field, wherein each pixel is a rectangular pixel having an aspect ratio; a light source arranged to illuminate the plurality of pixels to form the spatially-modulated light forming a holographic reconstruction at the replay field, wherein the holographic reconstruction comprises image content arranged to be viewed by a human viewer of the holographic projection system, wherein the rectangular replay field is spatially separated from the spatial light modulator and wherein the aspect ratio of each pixel is matched to the desired aspect ratio of the replay field such that the aspect ratio of the rectangular replay field is substantially equal to the aspect ratio of each pixel but with the rectangular replay field and each pixel orthogonally orientated with respect to each other. ### Claim 2 (depends on 1) A holographic projection system as claimed in claim 1 wherein the holographic reconstruction is formed by interference of the spatially-modulated light at the replay field. ### Claim 3 (depends on 1) A holographic projection system as claimed in claim 1 wherein the spatially-modulated light is diffracted by the pixels of the spatial light modulator. ### Claim 4 (depends on 1) A holographic projector as claimed in claim 1 wherein the aspect ratio of each pixel is greater than 1:1.2 and less than 1:3. ### Claim 5 (depends on 1) A holographic projection system as claimed in claim 1 wherein the pixel pitch in the one direction of the array is greater than the pixel pitch in the other direction of the array. ### Claim 6 (depends on 1) A holographic projection system as claimed in claim 1 wherein the array of pixels forms a substantially square array of rectangular pixels or a substantially circular array of rectangular pixels. ### Claim 7 (depends on 1) A holographic projection system as claimed in claim 1 wherein each pixel comprises a liquid crystal having a director. ### Claim 8 (depends on 7) A holographic projection system as claimed in claim 7, wherein the liquid crystal is a nematic liquid crystal. ### Claim 9 (depends on 1) A holographic projection system as claimed in claim 1 wherein the computer-generated hologram is a mathematical transformation of the holographic reconstruction. ### Claim 10 (depends on 9) A holographic projection system as claimed in claim 9 wherein: the mathematical transformation is a Fourier transform or a Fresnel transform, or the computer-generated hologram is a hologram generated by a point cloud method. ### Claim 11 (depends on 1) A holographic projection system as claimed in claim 1 wherein: each pixel is a light-modulating element, and/or each pixel comprises a phase-modulating element. ### Claim 12 (depends on 1) A holographic projection system as claimed in claim 1 wherein the pixels of the array of pixels are substantially parallel to each other. ### Claim 13 (depends on 1) A holographic projection system as claimed in claim 1 wherein spatial light modulator is a liquid crystal on silicon spatial light modulator. ### Claim 14 (depends on 1) A holographic projection system as claimed in claim 1 wherein: the light source is a monochromatic light source, and/or the light source is arranged to emit at least partially coherent light. ### Claim 15 (depends on 1) A holographic projection system as claimed in claim 1 wherein the holographic reconstruction is formed on a light-receiving surface at the replay field. ### Claim 16 (depends on 15) A holographic projection system as claimed in claim 15, wherein the light-receiving surface is a screen or diffuser. ### Claim 17 A method of forming a holographic reconstruction in a holographic replay field having a rectangular shape with an aspect ratio, the method comprising: receiving a computer-generated hologram; representing the computer-generated hologram on a spatial light modulator comprising a plurality of individually addressable pixels, wherein the pixels are rectangular pixels having an aspect ratio; spatially-modulating light in accordance with the computer-generated hologram using the spatial light modulator; forming a holographic reconstruction at the holographic replay field, wherein the holographic replay field is spatially separated from the spatial light modulator and wherein the aspect ratio of each pixel is matched to the desired aspect ratio of the replay field such that the aspect ratio of the holographic replay field is substantially equal to the aspect ratio of each pixel but with the replay field and each pixel orthogonally orientated with respect to each other, and wherein the holographic reconstruction comprises image content arranged to be viewed by a human viewer. ### Claim 18 A holographic projection system arranged to project light to a rectangular replay field having an aspect ratio, wherein the holographic projection system comprises: a spatial light modulator, comprising an array of individually addressable pixels, arranged to receive a computer-generated hologram and output spatially-modulated light forming a holographic reconstruction at the rectangular replay field, wherein each pixel is a rectangular pixel having an aspect ratio; a light source arranged to illuminate the plurality of pixels to form the spatially-modulated light forming a holographic reconstruction at the replay field, wherein the holographic reconstruction comprises image content arranged to be viewed by a human viewer of the holographic projection system, wherein the rectangular replay field is spatially separated from the spatial light modulator and wherein the aspect ratio of each pixel is matched to the desired aspect ratio of the replay field such that the aspect ratio of the rectangular replay field is substantially equal to the aspect ratio of each pixel but with the rectangular replay field and each pixel orthogonally orientated with respect to each other, wherein each pixel comprises a liquid crystal having a director substantially parallel to the longer side of the rectangular pixels. ### Claim 19 (depends on 18) A holographic projection system as claimed in claim 18, wherein the liquid crystal is a nematic liquid crystal.