# US 10,871,746 B2 · Method of displaying a hologram on a display device comprising pixels

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- Number: US 10,871,746 B2
- Document ID: US10871746B2
- Status: Granted
- Kind: B2
- Application number: 16/375,608
- Filed: 2019-04-04
- Published: 2019-11-28
- Granted: 2020-12-22
- Earliest claimed: 2018-05-25
- Assignees: Dualitas Ltd
- Applicants: Dualitas Ltd
- Inventors: Jamieson Christmas
- Web page: https://patentgrep.com/patent/US10871746B2

## CPC

- G03H 1/2294: {Addressing the hologram to an active spatial light modulator}
- G03H 1/0808: {Methods of numerical synthesis, e.g. coherent ray tracing [CRT], diffraction specific}
- G03H 1/0841: {Encoding method mapping the synthesized field into a restricted set of values representative of the modulator parameters, e.g. detour phase coding}
- G03H 1/2286: {Particular reconstruction light (G03H1/24 takes precedence); Beam properties}
- G09G 3/003: {to produce spatial visual effects}
- H04N 9/3105: {for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators (simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10)}
- G02F 1/136277: {formed on a semiconductor substrate, e.g. of silicon}
- G02F 1/136281: {having a transmissive semiconductor substrate}
- G02F 2203/02: reflective
- G02F 2203/12: spatial light modulator
- G03H 2001/0816: {Iterative algorithms}
- G03H 2001/0858: {Cell encoding wherein each computed values is represented by at least two pixels of the modulator, e.g. detour phase coding}
- G03H 2001/2297: {using frame sequential, e.g. for reducing speckle noise}
- G03H 2210/20: 2D object
- G03H 2222/12: Single or narrow bandwidth source, e.g. laser, light emitting diode [LED]
- G03H 2222/13: Multi-wavelengths wave with discontinuous wavelength ranges (G03H2222/18 takes precedence)
- G03H 2222/18: RGB trichrome light
- G03H 2222/34: Multiple light sources
- G03H 2225/60: Multiple SLMs
- G03H 2225/61: for multicolour processing
- G03H 2240/56: Resolution
- G03H 2240/62: Sampling aspect applied to sensor or display
- G09G 2320/064: by time modulation of the brightness of the illumination source
- 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})
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

There is provided a holographic projector comprising a hologram engine and a controller. The hologram engine is arranged to provide a hologram comprising a plurality of hologram pixels. Each hologram pixel has a respective hologram pixel value. The controller is arranged to selectively-drive a plurality of light-modulating pixels so as to display the hologram. Displaying the hologram comprises displaying each hologram pixel value on a contiguous group of light-modulating pixels of the plurality of light-modulating pixels such that there is a one-to-many pixel correlation between the hologram and the plurality of light-modulating pixels.

## Claims

### Claim 1

A method of displaying holograms using one or more spatial light modulators, each comprising light-modulating pixels, the method comprising:
receiving, at a spatial light modulator, a first hologram comprising a first plurality of hologram pixels each having a respective hologram pixel value;
displaying the first hologram on a plurality of light-modulating pixels of said spatial light modulator by displaying each hologram pixel value on a contiguous group of light-modulating pixels of the plurality of light-modulating pixels such that there is a one-to-many pixel correlation between each hologram pixel and the number of light-modulating pixels within the contiguous group, which display its pixel value, wherein each hologram pixel value within the first hologram is displayed on the same number of light-modulating pixels as each of the respective others
receiving, at a spatial light modulator, a second hologram comprising a second plurality of hologram pixels, each having a respective hologram pixel value; and
displaying the second hologram on a plurality of the light-modulating pixels of said spatial modulator by displaying each hologram pixel value on a contiguous group of light-modulating pixels of the plurality of light-modulating pixels such that there is a one-to-many or a one-to-one pixel correlation between each hologram pixel and the number of light-modulating pixels within the contiguous group displaying its pixel value, wherein each hologram pixel value within the second hologram is displayed on the same number of light-modulating pixels as each of the respective others; and
wherein a first number of light-modulating pixels are used to display each hologram pixel value of the first hologram and a second, different number of light-modulating pixels are used to display each hologram pixel value of the second hologram.

### Claim 2 (depends on 1)

A method of displaying holograms as claimed in claim 1 wherein the first hologram and second hologram are displayed on the same spatial light modulator.

### Claim 3 (depends on 1)

A method of displaying holograms as claimed in claim 1 wherein at least one light-modulating pixel is used to display a hologram pixel value of the first hologram at a first time and a hologram pixel value of the second hologram at a second time different to the first time.

### Claim 4 (depends on 1)

A method of displaying holograms as claimed in claim 1 wherein the first hologram is displayed on a first spatial light modulator and the second hologram is displayed on a second spatial light modulator.

### Claim 5 (depends on 1)

A method of displaying holograms as claimed in claim 1 further comprising illuminating the displayed hologram with light having a wavelength to project a holographic replay field having an area and illuminating the second displayed hologram with light having a second wavelength to project a second holographic replay field having a second area.

### Claim 6 (depends on 5)

A method of displaying holograms as claimed in claim 5 wherein the different number of light-modulating pixels used to display the hologram and the second hologram is such that the area and second area are substantially the same size.

### Claim 7 (depends on 6)

A method of displaying holograms as claimed in claim 6 further comprising overlapping the area and second area to form a composite colour replay field.

### Claim 8

A holographic projector comprising:
a hologram engine arranged to provide a first hologram comprising a plurality of hologram pixels each having a respective hologram pixel value and a second hologram comprising a second plurality of hologram pixels each having a respective hologram pixel value;
one or more spatial light modulators; and
a controller arranged to
selectively-drive a plurality of light-modulating pixels of one of the spatial light modulators so as to display the first hologram by displaying each hologram pixel value on a contiguous group of light-modulating pixels of the plurality of light-modulating pixels such that there is a one-to-many pixel correlation between each hologram pixel and the number of light-modulating pixels displaying its pixel value, such that each hologram pixel value within the first hologram is displayed on the same number of light-modulating pixels as each of the respective others, and
to selectively-drive a plurality of light-modulating pixels of one of the spatial light modulators so as to display the second hologram by displaying each hologram pixel value on a contiguous group of light-modulating pixels of the plurality of light-modulating pixels such that there is a one-to-many or a one-to-one pixel correlation between each hologram pixel and the number of light-modulating pixels displaying its pixel value, such that each hologram pixel value within the second hologram is displayed on the same number of light-modulating pixels as each of the respective others,
such that a first number of light-modulating pixels are used to display each hologram pixel value of the first hologram and a second, different number of light-modulating pixels are used to display each hologram pixel value of the second hologram.

### Claim 9 (depends on 8)

A holographic projector as claimed in claim 8 further comprising:
a light system arranged to illuminate the first displayed hologram with light having a wavelength so as to project a first holographic replay field having a first area; and
a second light system arranged to illuminate the second displayed hologram with light having a second wavelength so as to project a second holographic replay field having a second area.

### Claim 10 (depends on 9)

A holographic projector as claimed in claim 9 wherein the different number of light-modulating pixels used to display the first hologram and the second hologram is such that the area and second area are substantially the same size.

### Claim 11 (depends on 10)

A holographic projector as claimed in claim 10 further comprising a spatial light modulator arranged to display the hologram and second hologram or further comprising a spatial light modulator arranged to display the hologram and a second spatial light modulator arranged to display the second hologram.