Video Hologram and Device for Reconstructing Video Holograms for Large Objects

• US 20080252950A1
• Filed: 11/09/2007
• Published: 10/16/2008
• 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 8,027,071 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 operates so that the size of a reconstructed three dimensional scene is a function of the size of the hologram-bearing medium; the reconstructed three dimensional scene can then be anywhere within a volume defined by the hologram-bearing medium and a virtual observer window through which the reconstructed three dimensional scene must be viewed. This contrasts with conventional holograms, in which the size of the reconstructed scene is localised to a far smaller volume and is not a function of the size of the hologram-bearing medium at all.

Claims

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

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

wherein the size of the reconstructed three dimensional scene is a function of the size of the hologram-bearing medium and the reconstructed three dimensional scene can be anywhere within a volume defined by the hologram-bearing medium and a virtual observer window through which the reconstructed three dimensional scene must be viewed.

2. The device of claim 1 in which the observer window is constrained to be substantially at the image plane of the light source.

3. The device of claim 1 operable to time sequentially encode a hologram on the spatial light modulator first for one eye of an observer and then for the other eye of the observer.

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

5. The device of claim 1 which is operable such that a direct or inverse Fourier transform of the hologram is generated at an observer plane at which the observer'"'"'s eyes must be placed.

6. The device of claim 1 in which the virtual observer window is smaller than the spatial light modulator.

7. The device of claim 1 in which there are separate virtual observer windows, one for each eye of an observer.

8. The device of claim 7 in which each virtual observer window is approximately 1 cm×

1 cm.

9. The device of claim 7 operable to track the location of an observer'"'"'s eyes and to alter the position of the virtual observer windows so that the observer can maintain a view through each virtual observer window even when moving his or her head.

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

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

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

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

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

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

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

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

18. A method of generating a holographic reconstruction of a three dimensional scene, made up of multiple discrete points, using a display device and a computer, the device including a light source and an optical system to illuminate a spatial light modulator;

comprising the steps of;

(a) using the computer to encode a hologram on the spatial light modulator;

(b) arranging the optical system and the hologram such that the size of the reconstructed three dimensional scene is a function of the size of the spatial light modulator because the reconstructed three dimensional scene is anywhere within a volume spanned by the spatial light modulator and a virtual observer window through which the reconstructed three dimensional scene must be viewed and

(c) controlling the spatial light modulator such that, when a hologram comprises a region with information needed to reconstruct a single point in the three-dimensional scene, the point being visible from the virtual observer window, then the region (a) encodes information for that single point in the reconstructed three-dimensional scene and (b) 9s 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 virtual observer window.

19. A computer or computational device adapted to generate holographic reconstructions according to the method of claim 18.