Spatial light modulator for holographic projection

Patent metadata

Field	Value
Publication number	US-11243495-B2
Application number	US-201916680282-A
Country	US
Kind code	B2
Filing date	Nov 11, 2019
Priority date	Nov 12, 2018
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

There is provided a spatial light modulator arranged to display a light modulation pattern including a hologram. The spatial light modulator includes a liquid crystal on silicon spatial light modulator having a plurality of pixels. The hologram has a plurality of pixels. The spatial light modulator includes a silicon backplane. Each pixel of the spatial light modulator includes a light-modulating element and a respective pixel circuit. Each pixel circuit is embedded in the silicon backplane. Each pixel circuit is arranged to drive the corresponding light-modulating element. Each pixel circuit is further arranged to combine a received pixel value of the hologram with a corresponding pixel value of the light processing function such that the light modulation pattern further includes the light processing function. The light processing function includes a lens function and/or a grating function.

First claim

The invention claimed is:

1. A spatial light modulator having a plurality of pixels of the spatial light modulator arranged to display a light modulation pattern comprising a hologram having a plurality of pixels of the hologram,
wherein the spatial light modulator is a liquid crystal on silicon spatial light modulator comprising a silicon backplane and each pixel of the spatial light modulator comprises a light-modulating element and a respective pixel circuit embedded in the silicon backplane, wherein each pixel circuit is arranged to drive the respective light-modulating element, and
each pixel circuit is further arranged to combine a received pixel value of the hologram with a corresponding pixel value of a light processing function such that the light modulation pattern further comprises the light processing function,
wherein the light processing function comprises a lens function or a grating function.

2. A spatial light modulator as claimed in claim 1 wherein the hologram comprises [x×y] pixels and the spatial light modulator comprises [m×n] pixels, wherein mn>xy, and the silicon backplane further comprises pixel mapping circuitry arranged to receive each pixel value of the hologram and route each pixel value of the hologram to a plurality of the pixels of the spatial light modulator such that the hologram is tiled onto the light-modulating elements of the spatial light modulator using the pixel mapping circuitry.

3. A spatial light modulator as claimed in claim 2 wherein the pixel mapping circuitry is arranged to change a scheme for routing each pixel value of the hologram to a plurality of pixels of the spatial light modulator in accordance with a tiling scheme.

4. A spatial light modulator as claimed in claim 1 wherein m≥2x and n≥2y and each pixel value of the hologram is routed to at least four pixels of the spatial light modulator.

5. A spatial light modulator as claimed in claim 1 wherein the hologram is tiled onto the spatial light modulator such that there is displayed thereon at least one full-tile of the hologram, wherein a full-tile of the hologram is a complete, contiguous group of [x×y] pixels of the hologram.

6. A spatial light modulator as claimed in claim 1 wherein adjacent tiles of the hologram are connected end to end.

7. A spatial light modulator as claimed in claim 1 wherein each pixel circuit comprises a pixel capacitor connected to the light-modulating element, wherein the pixel capacitor is arranged to charge the light-modulating element.

8. A holographic projector comprising the spatial light modulator as claimed in claim 1 and a light source arranged to illuminate the light modulation pattern with coherent light such that a holographic reconstruction corresponding to the hologram is formed on a replay plane spatially separated from the spatial light modulator.

9. A holographic projector as claimed in claim 8 further comprising a driver arranged to send a plurality of holograms, each comprising [x×y] pixels, to the spatial light modulator.

10. A method of displaying a light modulation pattern comprising a hologram having a plurality of pixels of the hologram on a spatial light modulator having a plurality of pixels of the spatial light modulator, wherein the spatial light modulator is a liquid crystal on silicon spatial light modulator comprising a silicon backplane and each pixel of the spatial light modulator comprises a light-modulating element and a respective pixel circuit embedded in the silicon backplane, and the method comprises each pixel circuit:
combining a received pixel value of the hologram with a corresponding pixel value of a light processing function such that the light modulation pattern displayed on the spatial light modulator further comprises the light processing function, wherein the light processing function is a lens function or a grating function.

11. A method of displaying a light modulation pattern as claimed in claim 10 , wherein the hologram comprises [x×y] pixels and the spatial light modulator comprises [m×n] pixels, wherein mn>xy, and the method further comprises:
routing each pixel value of the hologram to a plurality of pixels of the spatial light modulator using pixel mapping circuitry embedded in the silicon backplane of the spatial light modulator such that the hologram is tiled onto the light-modulating elements of the spatial light modulator.

12. A method of displaying a light modulation pattern as claimed in claim 10 wherein the hologram is tiled onto light-modulating elements of the spatial light modulator by connecting tiles of the hologram end to end.

13. A method of holographic projection comprising the method of displaying a light modulation pattern as claimed in claim 10 and further comprising illuminating the light modulation pattern with coherent light from a light source to form a holographic reconstruction corresponding to the hologram on a replay plane spatially separated from the spatial light modulator.

14. A method of holographic projection according to claim 13 , further comprising reperforming the method steps of claim 13 to form a second holographic reconstruction corresponding to a second hologram and using the grating function to displace the second holographic reconstruction on the replay plane with respect to a first holographic reconstruction such that image spots of the second holographic reconstruction are formed in the spaces between image spots of the first holographic reconstruction.

15. A method of holographic projection as claimed in claim 14 wherein the first and second holographic reconstructions are interlaced such that a viewer of the replay plane perceives a holographic reconstruction having a higher resolution than the first holographic reconstruction or second holographic projection alone.

Assignees

• Dualitas Ltd

Inventors

• Christmas Jamieson

Classifications

• G03H2001/2228

  adapted for reflection and transmission reconstruction · CPC title

• G03H1/2294 Primary

  Addressing the hologram to an active spatial light modulator · CPC title

• G03H2001/2213

  Diffusing screen revealing the real holobject, e.g. container filed with gel to reveal the 3D holobject · CPC title

• G03H2001/0224

  Active addressable light modulator, i.e. Spatial Light Modulator [SLM] · CPC title

• G03H2001/2255

  Holobject out of Fourier or hologram planes · CPC title