Video hologram and device for reconstructing video holograms

• US 20060055994A1
• Filed: 11/11/2003
• Published: 03/16/2006
• 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 7,839,548 B2
• Time in Patent Office: Days
• US Class Current: 359/15
• 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

The invention relates to video holograms and devices for reconstructing video holograms, comprising an optical system that consists of a light source, lens and the video hologram that is composed of cells arranged in a matrix or a regular pattern with at least one opening per cell, the phase or amplitude of said opening being controllable. The video holograms and devices for reconstructing the same are characterised in that holographic video representations of expanded spatial objects can be achieved in a wide viewing area in real time using controllable displays, whereby the objects are either computer-generated or created by different means. The space-bandwidth product (SBP) of the hologram is thus reduced to a minimum and the periodicity interval of the Fourier spectrum is used as a viewing window on the inverse transformation plane, through which the object is visible in the preceding space. The mobility of the viewer(s) is achieved by tracking the viewing window. The invention can be advantageously used in the television, multimedia, games and construction fields, in military and medical technology, in addition to other economic and social areas.

Claims

1. Video hologram and device for reconstructing video holograms, comprising an optical system that consists of at least one real or virtual point light source or line light source which provides sufficiently coherent light, a lens and a hologram-bearing medium, composed of cells arranged in a matrix or in an otherwise regular pattern with at least one opening per cell, the phase or amplitude of said opening being controllable, and a viewing plane located at the image plane of the light source, wherein

in the viewing plane at least one viewing window (5) is located in a periodicity interval of the reconstruction by the Fourier transform of the video hologram (3), through which the reconstruction of a three-dimensional scene (6) is visible, and the extension of the viewing window (5) is not greater than the periodicity interval.

2. Video hologram and device according to claim 1, wherein the viewing window (5) is approximately limited and positioned in relation to one eye, an eye distance of a viewer or to another suitable area.

3. Video hologram and device according to claim 1, wherein the other eye of the viewer is assigned a second viewing window (5′

) achieved by a second, real or virtual, sufficiently coherent light source (1′

) being turned on at another suitable position to form a pair of light sources in the optical system.

4. Video hologram and device according to claim 3, wherein the optical system and the hologram-bearing medium (3) are arranged so that the higher diffraction orders of the video hologram (3) for the first viewing window (5) have a zero point or an intensity minimum at the position of the second viewing window (5′

).

5. Video hologram and device according to claim 4, wherein the hologram-bearing medium (3) can be re-encoded for the second eye synchronously to turning on the second viewing window (5′

).

6. Video hologram and device according to claim 3, wherein several light sources can be turned on for several viewers.

7. Video hologram and device according to claim 1, wherein the light sources can be positioned by mechanical or electronic displacement, by movable mirrors or in another suitable way.

8. Video hologram and device according to claim 1, wherein information required to determine the position of the light sources is provided by at least one position sensor according to the position of the viewer(s).

9. Video hologram and device according to claim 1, wherein a video hologram is reconstructed in colour, wherein the hologram-bearing medium (3) being composed of cells arranged in a matrix or in an otherwise regular pattern with at least three openings per cell, representing the three primary colours, the phase and/or amplitude of said openings being controllable, and said openings being encoded individually for each primary colour.

10. Video hologram and device according to claim 1, wherein the colour reconstruction is achieved by at least three subsequently performed reconstructions in the individual primary colours.