Holographic display apparatus and method for providing expanded viewing window

Patent metadata

Field	Value
Publication number	US-11567451-B2
Application number	US-202117357180-A
Country	US
Kind code	B2
Filing date	Jun 24, 2021
Priority date	Jul 25, 2019
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

A holographic display apparatus capable of providing an expanded viewing window and a display method are provided. The holographic display apparatus includes an image processor configured to provide computer generated hologram (CGH) data to a spatial light modulator, wherein the image processor is further configured to generate a hologram data array comprising information of the holographic image to be reproduced at the first resolution or a resolution less than the first resolution, perform an off-axis phase computation on the hologram data array at the second resolution, and then, generate the CHG data at the first resolution.

First claim

What is claimed is:

1. A holographic display apparatus comprising:
a light source configured to emit an illumination light;
a spatial light modulator comprising a plurality of display pixels two-dimensionally arranged at a first resolution to display a hologram pattern for modulating the illumination light to reproduce a holographic image;
an illumination optical system configured to provide the illumination light to the spatial light modulator such that the illumination light is incident on the spatial light modulator in irregular directions; and
an image processor configured to:
generate a hologram data array comprising information of the holographic image to be reproduced at the first resolution or a resolution less than the first resolution;
perform an off-axis phase computation on the hologram data array at a second resolution higher than the first resolution; and
generate computer generated hologram (CGH) data at the first resolution; and
provide the CGH data to the spatial modulator.

2. The holographic display apparatus of claim 1 , wherein the illumination optical system comprises a transparent light guide plate and an output coupler disposed on the transparent light guide plate, the output coupler being configured to allow the illumination light to travel irregularly in a plurality of different directions within each display pixel of the plurality of display pixels.

3. The holographic display apparatus of claim 2 , wherein the output coupler is configured such that a first portion of the illumination light output from the output coupler is incident on the spatial light modulator as a parallel light and a second portion of the illumination light is obliquely incident on the spatial light modulator.

4. The holographic display apparatus of claim 3 , wherein the first portion of the illumination light is vertically incident on a first area of each display pixel of the plurality of display pixels and the second portion of the illumination light is incident on a second area of each display pixel of the plurality of display pixels.

5. The holographic display apparatus of claim 4 , wherein the image processor comprises a memory configured to store a direction distribution of a traveling direction of the illumination light incident on the spatial light modulator.

6. The holographic display apparatus of claim 4 , wherein
the image processor is further configured to, when performing the off-axis phase computation,
generate an off-axis phase array at the second resolution;
select data from the off-axis phase array based on positions of the first areas of the plurality of display pixels and convert the selected data to have the first resolution; and
multiply the hologram data array by the selected data having the first resolution.

7. The holographic display apparatus of claim 4 , wherein
the image processor is further configured to, when performing the off-axis phase computation,
generate an off-axis phase array at the second resolution;
upscale the hologram data array at the second resolution;
multiply the off-axis phase array by the upscaled hologram data array; and
select data from the hologram data array based on positions of the first areas of the plurality of display pixels and convert the hologram data array into the first resolution.

8. The holographic display apparatus of claim 4 , wherein
the image processor comprises a previously calculated phase array that was previously calculated to transmit an image displayed on positions of the first areas of the plurality of display pixels to a position of an observer's eye, and
wherein the previously calculated phase array comprises a plurality of phase arrays respectively corresponding to different positions of the observer's eye.

9. The holographic display apparatus of claim 8 , wherein
the image processor is further configured to, when performing the off-axis phase computation,
select the previously calculated phase array corresponding to the position of the observer's eye; and
multiply the hologram data array by the selected previously calculated phase array.

10. The holographic display apparatus of claim 1 , wherein
the image processor is further configured to:
in order to generate the hologram data array,
receive image data;
perform a first Fourier operation on the image data for each depth of the image data;
perform a lens phase operation on the image data for each depth obtained after the first Fourier operation;
merge the image data for each depth obtained after the lens phase operation into a single merged image data; and
perform a second Fourier operation on the single merged image data.

11. The holographic display apparatus of claim 10 , wherein
the first Fourier operation comprises a first inverse Fourier transform that converts a first light wavefront configured to be formed in an observer's retina into a second light wavefront configured to be formed in an observer's pupil, and the second Fourier operation comprises a second inverse Fourier transform that converts the second light wavefront into a third wavefront formed in a plane of the spatial light modulator.

12. A display method performed by a holographic display apparatus comprising an image processor, a spatial light modulator configured to form a hologram pattern for modulating an incident light and reproducing a holographic image and comprising a plurality of display pixels two-dimensionally arranged at a first resolution, and an illumination optical system configured to provide an illumination light to the spatial light modulator such that the illumination light is incident on the spatial light modulator in irregular directions, the display method comprising:
generating, by the image processor, a hologram data array comprising information of the holographic image to be reproduced at the first resolution or a resolution less than the first resolution;
performing, by the image processor, an off-axis phase computation on the hologram data array at a second resolution higher than the first resolution;
generating, by the image processor, computer generated hologram (CGH) data at the first resolution; and
providing the CGH data from the image processor to the spatial light modulator.

13. The display method of claim 12 , wherein the illumination optical system comprises a transparent light guide plate and an output coupler disposed on the transparent light guide plate, the output coupler being configured to allow the illumination light to travel irregularly in various directions within each display pixel of the plurality of display pixel.

14. The display method of claim 13 , wherein the output coupler is configured such that a first portion of the illumination light output from the output coupler is incident on the spatial light modulator as a parallel light and a second portion of the illumination light is obliquely incident on the spatial light modulator.

15. The display method of claim 14 , wherein the first portion of the illumination light is vertically incident on a first area of each display pixel of the plurality of display pixels and the second portion of the illumination light is incident on a second area of each display pixel of the plurality of display pixels.

16. The display method of claim 15 , wherein
the performing the off-axis phase computation comprises:
generating an off-axis phase array at the second resolution;
selecting data from the off-axis phase array based on positions of the first areas of the plurality of display pixels and converting the selected data to have the first resolution; and
multiplying the h

Assignees

• Samsung Electronics Co Ltd
• Univ Korea Res & Business Foundation Sejong Campus
• Korean Univ Research And Business Foundation Sejong Campus

Inventors

• Song Hoon
• Kim Hwi
• An Jungkwuen
• Lee Hongseok
• Kim Yunhee
• Choi Chilsung

Classifications

• G03H1/2294 Primary

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

• G03H2223/13

  Phase mask · CPC title

• G03H2226/02

  Computing or processing means, e.g. digital signal processor [DSP] · CPC title

• G03H2223/15

  Colour filter, e.g. interferential colour filter · CPC title

• G06T3/4084

  in the transform domain, e.g. fast Fourier transform [FFT] domain scaling · CPC title