COMPACT HOLOGRAPHIC DISPLAY DEVICE

• US 20100046050A1
• Filed: 10/26/2007
• Published: 02/25/2010
• Est. Priority Date: 10/26/2006
• Status: Active Grant

• Current Assignee: SeeReal Technologies S.A.
• Original Assignee: SeeReal Technologies S.A.
• Inventors: Schwerdtner, Armin, Haussler, Ralf, Kroll, Bo
• Granted Patent: US 8,416,479 B2
• Time in Patent Office: Days
• US Class Current: 359/9
• CPC Class Codes: G03H 1/02 Details of features involved during the holographic process; Replication of holograms without interference recording
• CPC Class Codes: G03H 1/2205 using downstream optical component
• CPC Class Codes: G03H 1/2249 Holobject properties
• CPC Class Codes: G03H 1/2294 Addressing the hologram to an active spatial light modulator
• CPC Class Codes: G03H 2001/0224 Active addressable light modulator, i.e. Spatial Light Modulator [SLM]
• CPC Class Codes: G03H 2001/2218 being perpendicular to optical axis
• CPC Class Codes: G03H 2001/2242 Multiple viewing windows
• CPC Class Codes: G03H 2001/2292 Using scanning means
• CPC Class Codes: G03H 2001/2297 using frame sequential, e.g. for reducing speckle noise
• CPC Class Codes: G03H 2001/261 in optical contact
• CPC Class Codes: G03H 2001/264 One hologram being a HOE
• CPC Class Codes: G03H 2001/303 Interleaved sub-holograms, e.g. three RGB sub-holograms having interleaved pixels for reconstructing coloured holobject
• CPC Class Codes: G03H 2210/20 2D object
• 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 2222/35 Transverse intensity distribution of the light beam
• CPC Class Codes: G03H 2223/16 Optical waveguide, e.g. optical fibre, rod
• CPC Class Codes: G03H 2223/19 Microoptic array, e.g. lens array
• CPC Class Codes: G03H 2223/21 Anamorphic optical element, e.g. cylindrical
• CPC Class Codes: G03H 2225/22 : Electrically addressed SLM [EA-SLM]
• CPC Class Codes: G03H 2225/33 : Complex modulation
• CPC Class Codes: G03H 2225/55 : Having optical element registered to each pixel
• CPC Class Codes: G03H 2225/60 : Multiple SLMs
• CPC Class Codes: G03H 2226/05 : Means for tracking the observer
• CPC Class Codes: G03H 2227/02 : Handheld portable device, e.g. holographic camera, mobile holographic display
• CPC Class Codes: G03H 2227/05 : Support holding the holographic record
• CPC Class Codes: G03H 2240/61 : SLM related parameters, e.g. pixel size

Abstract

Holographic display device comprising a first EASLM and a second EASLM, the pair permitting independent modification of phase and amplitude, in which holographic reconstruction is visible through one or more virtual observer windows. An advantage is that an observer may view a holographic reconstruction through one or more virtual observer windows from a device housing a pair of EASLMs which permit independent modification of phase and amplitude.

Claims

1. Holographic display device comprising a first electrically addressed spatial light modulator (EASLM) and a second EASLM, the pair permitting independent modification of phase and amplitude, in which holographic reconstruction is visible through one or more virtual observer windows.

3. The holographic display device of claim 1 in which the display is illuminated with a backlight and micro-lens array or in which a light source is light emitting diodes.

5. The holographic display device of claim 1 in which one EASLM modifies phase, and the other EASLM modifies amplitude or in which one EASLM modifies a combination of phase and amplitude, and the other EASLM modifies a different combination of phase and amplitude.

7. The holographic display device of claim 1 in which there are no intermediary optics between the EASLMs or in which the EASLMs form adjacent layers with a small or minimal separation.

9. The holographic display device of claim 1 in which the EASLMs are in fixed, direct or indirect physical attachment or in which a light source is in fixed direct or indirect physical attachment to an EASLM.

11. The holographic display device of claim 1 in which the EASLMs have aligned pixels with respect to the virtual observer windows.

12. The holographic display device of claim 1 in which the diffraction of the light from the first EASLM to the second EASLM is in the Fresnel diffraction regime, but excluding the Fraunhofer diffraction regime.

13. The holographic display device of claim 1 in which greater than 90% of the intensity transmitted by each pixel of the first EASLM is incident on the corresponding pixel of the second EASLM, considered in a two dimensional cross-section.

14. The holographic display device of claim 1 in which an isolation layer separates the EASLMs to minimize the electromagnetic fields from one EASLM adversely affecting the performance of the neighbouring EASLM.

15. The holographic display device of claim 1 in which a lens array is placed between the EASLMs to minimize cross-talk.

16. The holographic display device of claim 1 in which the aperture of pixels in the first EASLM is reduced to minimize cross-talk.

17. The holographic display device of claim 1 in which a fibre-optic faceplate sits between the EASLMs to minimize cross-talk.

18. The holographic display device of any preceding claim 1 in which virtual observer windows can be tiled using spatial or time multiplexing.

19. The holographic display device of claim 1 in which the display is operable to time sequentially re-encode a hologram on a hologram-bearing medium for the left and then the right eye of an observer.

20. The holographic display device of claim 1 in which the display generates a 2D image that is in focus on a screen independent of the distance of the screen from the device in the optical far field without the need for any projection lenses or in which the EASLMs are positioned within 30 mm or a light source and housed within a portable casing.

21. The holographic display device of claim 1 in which a holographic image is sent to each eye of an observer using a beamsplitter.

23. The holographic display device of claim 1 in which a beam steering element is present for tracking VOWs, the beam steering element comrising liquid crystal domains inside an isotropic host material, where the interfaces between the domains and the matrix are prism-shaped, or the shape of sections of a sphere, or the shape of sections of a cylinder, and the orientation of the liquid crystals are controlled using externally applied electric fields so as to vary the local refractive or diffractive properties of the beam steering element.

24. The holographic display device of claim 1 in which the EASLMs, a light source and a lens array aligned with the light source, are all housed within a portable casing and in which the light source is magnified between 10 and 60 times by the lens array.

25. A method of generating a holographic reconstruction comprising the step of using a holographic display device as claimed in claim 1.

26. The device of claim 1 in which a beam steering element is present for tracking virtual observer windows (VOWs), the beam steering element comprising controllable prism arrays with prism elements, the prism array especially being in the form of an electro-wetting prism array, a prism element comprising electrodes and a cavity filled with two separate liquids and an interface between the liquids, the slope of the interface between the liquids being electrically controllable by applying voltage to the electrodes.

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