VIDEO HOLOGRAM AND DEVICE FOR RECONSTRUCTING VIDEO HOLOGRAMS WITH WINDOW AT IMAGE PLANE

• US 20060238836A1
• Filed: 06/29/2006
• Published: 10/26/2006
• Est. Priority Date: 11/13/2002
• Status: Active Grant

• Current Assignee: SeeReal Technologies GmbH (SeeReal Technologies S.A.)
• Original Assignee: SeeReal Technologies GmbH (SeeReal Technologies S.A.)
• Inventors: SCHWERDTNER, ARMIN
• Granted Patent: US 8,314,981 B2
• Time in Patent Office: Days
• US Class Current: 359/9
• CPC Class Codes: G03H 1/08 Synthesising holograms, i.e. holograms synthesized from objects or objects from hologramsusing electric digital computers G06F; G06T
• CPC Class Codes: G03H 1/16 using Fourier transform G03H1/10, G03H1/12, G03H1/14 take precedence; analogue computers G06G, e.g. G06G7/19
• CPC Class Codes: G03H 1/2286 Particular reconstruction light G03H1/24 takes precedence; Beam properties
• CPC Class Codes: G03H 1/2294 Addressing the hologram to an active spatial light modulator
• CPC Class Codes: G03H 2001/0858 Cell encoding wherein each computed values is represented by at least two pixels of the modulator, e.g. detour phase coding
• CPC Class Codes: G03H 2001/2236 Details of the viewing window
• CPC Class Codes: G03H 2001/2242 Multiple viewing windows
• CPC Class Codes: G03H 2001/2271 RGB holobject
• CPC Class Codes: G03H 2210/30 3D object
• CPC Class Codes: G03H 2222/22 Spatial coherence
• CPC Class Codes: G03H 2222/34 Multiple light sources
• CPC Class Codes: G03H 2226/05 Means for tracking the observer

Abstract

A video holographic display device includes a light source used to illuminate a hologram-bearing medium encoded with a hologram. The device operates so that only when an observer'"'"'s eyes are positioned approximately at the image plane of the light source can the holographic reconstruction be seen properly. This contrasts with conventional holographic displays, in which the observer'"'"'s eyes do not have to be at the image plane in order for a holographic reconstruction to be seen.

Claims

1. A display device for video holography, in which the device enables a holographic reconstruction of a three dimensional scene to be viewed;

the device including a light source and an optical system to illuminate a hologram-bearing medium encoded with a hologram;

wherein the device is operable such that only when an observer'"'"'s eyes are positioned approximately at the image plane of the light source can the holographic reconstruction be seen properly.

2. The device of claim 1 in which the holographic reconstruction can occur anywhere within a volume defined by the hologram and a virtual observer window formed on the image plane, through which the observer is required to view the reconstruction.

3. The device of claim 1 in which the hologram comprises a region with information needed to reconstruct a single point in the three dimensional scene, the point being visible from a defined viewing position, and is characterised in that:

the region (a) encodes information for that single point in the reconstructed three dimensional scene and (b) is the only region in the hologram encoded with information for that point, and (c) is restricted in size to form a portion of the entire hologram, the size being such that multiple reconstructions of that point caused by higher diffraction orders are not visible at the defined viewing position.

4. The device of claim 1 operable to time sequentially re-encode a hologram on the hologram-bearing medium for the left and then the right eye of an observer.

5. The device of claim 1 operable such that the holographic reconstruction is the Fresnel transform of the hologram and not the Fourier transform of the hologram.

6. The device of claim 1 which is operable such that a direct or inverse Fourier transform of the hologram is generated at the image plane.

7. The device of claim 2 in which the observer window is smaller than the hologram-bearing medium.

8. The device of claim 2 in which there are separate observer windows, one for each eye of the observer.

9. The device of claim 8 in which each observer window is approximately 1 cm×

1 cm.

10. The device of claim 8 in which the locations of an observer'"'"'s eyes are tracked and the device can alter the positions of the virtual observer windows so that the observer can maintain a view through each observer window even when moving his or her head.

11. The device of claim 2 in which the size of the observer window is calculated as a function of the periodicity interval of the hologram.

12. The device of claim 1 in which the light source includes several light sources.

13. The device of claim 1 in which the light source includes one or more virtual light sources.

14. The device of claim 1 in which the hologram bearing medium is a TFT flat screen.

15. The device of claim 1 in which the device is a television.

16. The device of claim 1 in which the device is a multimedia device.

17. The device of claim 1 in which the device is a gaming device.

18. The device of claim 1 in which the device is a medical image display device.

19. The device of claim 1 in which the device is a military information display device.

20. A holographic reconstruction generated by the display device defined in claim 1.

21. A method of generating a holographic reconstruction of a three dimensional scene using a display device and a computer, the device including a light source and an optical system to illuminate a hologram-bearing medium;

comprising the steps of;

(a) using the computer to encode a hologram on the hologram-bearing medium;

(b) arranging for the image plane of the light source to co-incide approximately with the plane of the observer'"'"'s eyes to enable the observer to view the reconstruction.

22. A computer adapted to generate holographic reconstructions according to the method of claim 21.