Method and apparatus for correcting distortion on holographic display

Patent metadata

Field	Value
Publication number	US-9851693-B2
Application number	US-201615007389-A
Country	US
Kind code	B2
Filing date	Jan 27, 2016
Priority date	Jan 29, 2015
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A method and apparatus for correcting a distortion of a holographic display. The method includes tracking a location of a viewing window by tracking a location of a pupil of a user and calculating a central location of the viewing window, generating a wavefront aberration by determining an object point and an image point based on a location of a light source and the central location of the viewing window and using ray tracing, and calculating a complex aberration light field using the generated wavefront aberration. Thus, a quality of a holographically reproduced image in a viewing window-based holographic display may be improved.

First claim

The invention claimed is:

1. A method of correcting a distortion of a holographic display to be performed by an apparatus for correcting a distortion of a holographic display, the method comprising:
tracking a location of a viewing window by calculating a central location of the viewing window based on a location of a pupil of a user;
generating a wavefront aberration by determining an object point and an image point based on a location of a light source and the central location of the viewing window, and using ray tracing; and
correcting a distortion of a holographic display using the generated wavefront aberration,
wherein the generating of the wavefront aberration comprises:
generating the wavefront aberration in an exit pupil using ray tracing of an optical system of the holographic display; and
generating the wavefront aberration of coordinates of the exit pupil by calculating a first optical path spanning from an image point on an image plane to the exit pupil and a second optical path spanning from a reference spherical wavefront of the exit pupil to the central location of the viewing window.

2. The method of claim 1 , further comprising:
generating a computer-generated hologram (CGH) in which the distortion is corrected using a calculated complex light field; and
reproducing a hologram by encoding the CGH based on a spatial light modulator.

3. The method of claim 2 , wherein:
the generating of the CGH comprises generating the CGH by calculating a corrected, light field value of an object on a spatial light modulator plane, and
the reproducing of the hologram comprises reproducing the hologram for a stereoscopic image to be formed in a space by transforming the light field value of the object on the spatial light modulator plane based on an optical modulation characteristic of the spatial light modulator, and performing optical modulation.

4. The method of claim 1 , wherein the tracking of the location of the viewing window comprises:
calculating the central location of the viewing window by tracking the location of the pupil using a pupil image of the user obtained from an image sensor.

5. The method of claim 1 , wherein the generating of the wavefront aberration comprises:
generating the wavefront aberration by determining the central location of the viewing window to be the image point and determining a point source on an optical axis to be the object point.

6. The method of claim 1 , wherein;
the optical system is a convergent optical system, and
the exit pupil is an exit pupil of the convergent optical system.

7. The method of claim 6 , wherein the generating of the wavefront aberration comprises:
generating a wavefront aberration of a convergent optical system of all coordinates of the exit pupil by calculating a difference between the first optical path and the second optical path.

8. A method of correcting a distortion of a holographic display to be performed by an apparatus for correcting a distortion of a holographic display, the method comprising:
tracking a location of a viewing window by calculating a central location of the viewing window based on a location of a pupil of a user;
generating a wavefront aberration by determining an object point and an image point based on a location of a light source and the central location of the viewing window, and using ray tracing; and
correcting a distortion of a holographic display using the generated wavefront aberration,
wherein the correcting of the distortion comprises:
correcting the distortion of the holographic display by calculating a complex aberration light field by applying an aberration light field in which the wavefront aberration is a negative value.

9. The method of claim 8 , wherein, when an object to be displayed is a stereoscopic object, the correcting of the distortion comprises:
correcting the distortion of the holographic display by dividing the object into successive object planes and calculating a sum of respective complex aberration light fields.

10. An apparatus for correcting a distortion of a holographic display, the apparatus comprising:
a processor; and
a memory having instructions stored thereon executed by the processor to perform;
tracking a location of a viewing window by calculating a central location of the viewing window based on a location of a pupil of a user;
generating a wavefront aberration by determining an object point and an image point based on a location of a light source and the central location of the viewing window, and using ray tracing; and
correcting a distortion of a holographic display by calculating a complex aberration light field using the generated wavefront aberration,
wherein the wavefront aberration in an exit pupil is generated by using ray tracing of an optical system of the holographic display, and
wherein the wavefront aberration of coordinates of the exit pupil is generated by calculating a first optical path spanning from an image point on an image plane to the exit pupil and a second optical path spanning from a reference spherical wavefront of the exit pupil to the central location of the viewing window.

11. The apparatus of claim 10 ,
wherein the processor is further configured to:
generate a CGH in which a distortion is corrected using a calculated complex light field; and
reproduce a hologram by encoding the CGH based on a spatial light modulator.

12. The apparatus of claim 11 , wherein the processor is further configured to:
generate the CGH by calculating a corrected light field value of an object on a spatial light modulator plane; and
reproduce a hologram for a stereoscopic image to be formed in a space by transforming a light, field value of the object on the spatial light modulator plane based on an optical modulation characteristic of the spatial light modulator, and performing optical modulation.

13. The apparatus of claim 10 , wherein the processor is further configured to calculate the central location of the viewing window by tracking the location of the pupil using a pupil image of the user obtained from an image sensor.

14. The apparatus of claim 10 , wherein the processor is further configured to generate the wavefront aberration by determining the central location of the viewing window to be the image point and determining a point source on an optical axis to be the object point.

15. The apparatus of claim 10 , wherein:
the optical system is a convergent optical system, and
the exit pupil is an exit pupil of the convergent optical system.

16. The apparatus of claim 15 , wherein the processor is further configured to generate a wavefront aberration of the convergent optical system of all coordinates of the exit pupil by calculating a difference between the first optical path and the second optical path.

17. The apparatus of claim 10 , wherein the processor is further configured to calculate a complex aberration light, field by applying an aberration light field in which the wavefront aberration is a negative value.

18. The apparatus of claim 17 , wherein, when an object to be displayed is a stereoscopic object, the processor is further configured to calculate the complex aberration light field by dividing the object into successive object planes, calculating a complex aberration light field of each object plane, and calculating, a sum of calculated respective complex aberration light fields.

Assignees

• Electronics & Telecommunications Res Inst

Inventors

• Park Min Sik
• Kim Hyun Eui

Classifications

• G03H1/0486 Primary

  Improving or monitoring the quality of the record, e.g. by compensating distortions, aberrations · CPC title

• G06F3/013

  Eye tracking input arrangements (G06F3/015 takes precedence) · CPC title

• G03H1/2294

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

• G03H1/0808

  Methods of numerical synthesis, e.g. coherent ray tracing [CRT], diffraction specific · CPC title

• G03H2001/0825

  Numerical processing in hologram space, e.g. combination of the CGH [computer generated hologram] with a numerical optical element · CPC title