Spatial Light Modulator Using Electrowetting Cells

• US 20100232000A1
• Filed: 10/17/2008
• Published: 09/16/2010
• Est. Priority Date: 10/19/2007
• Status: Active Grant

• Current Assignee: SeeReal Technologies S.A.
• Original Assignee: SeeReal Technologies S.A.
• Inventors: Futterer, Gerald, Reichelt, Stephan
• Granted Patent: US 8,498,053 B2
• Time in Patent Office: Days
• US Class Current: 359/9
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G03H 1/02 Details of features involved during the holographic process; Replication of holograms without interference recording
• CPC Class Codes: G03H 1/22 Processes or apparatus for obtaining an optical image from holograms G03H1/26 - G03H1/34 take precedence
• 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 2001/2297 using frame sequential, e.g. for reducing speckle noise
• CPC Class Codes: G03H 2225/24 Having movable pixels, e.g. microelectromechanical systems [MEMS]
• CPC Class Codes: G03H 2225/31 Amplitude only
• CPC Class Codes: G03H 2225/32 Phase only
• 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 2240/43 Continuous

Abstract

A spatial light modulator for modulating light field amplitude comprises a surface relief grating adapted to act as a diffractive lens, where a material is used to fill at least one groove of a surface grating structure, such that a controllable refractive index birefringence of the material inside the surface relief grating is controlled by an electric field, which leads to a controllable intensity at a fixed focal point.

Claims

1. A spatial light modulator for modulating light field amplitude comprising a surface relief grating adapted to act as a diffractive lens, where a material is used to fill at least one groove of a surface grating structure, such that a controllable refractive index of the material inside the surface relief grating is controlled by an electric field, which leads to a controllable intensity at a fixed focal point.

2. The spatial light modulator of claim 1, in which the material is a liquid crystal, and the controllable refractive index is the controllable refractive index n_LC of the liquid crystal or in which the material is an electro-optic material, and the controllable refractive index is the controllable refractive index of the electro-optic material.

4. The spatial light modulator of claim 1, in which the surface relief grating is a discontinuously or a continuously shaped surface relief structure.

5. The spatial light modulator of claim 1, in which contrast is enhanced using an aperture stop and in which a spherical lens or ball lens is used inside the aperture stop or in which contrast is enhanced using an aperture stop and an axicon or a variable axicon.

8. The spatial light modulator of claim 5, in which the axicon has one surface which is the surface of a lens.

9. The spatial light modulator of claim 1, in which the light modulation switching time is less than or equal to 5 ms and/or greater than or equal to 100 microseconds or in which the spatial light modulator is operable at conventional switching frequencies.

11. The spatial light modulator of claim 1, in which the spatial light modulator is used with sparse object reconstruction.

12. The spatial light modulator of claim 1, in which contrast is enhanced using a Fabry-Perot interferometer.

13. The spatial light modulator of claim 1, in which the spatial light modulator is used in a 3D display or in a holographic display or in a stereoscopic display or in which the spatial light modulator is used in a two dimensional amplitude modulating display.

15. The spatial light modulator of claim 13 in which one or two virtual observer windows for the eyes of one or more observers are used.

17. The spatial light modulator of claim 1, in which the modulated light is visible light and/or near infra red light and/or near ultraviolet light or in which the spatial light modulator is used in military applications, especially in laser radar systems.

19. The spatial light modulator of claim 1, in which the spatial light modulator is used to form a secondary light source or in which the spatial light modulator is used to form a light source array with variable amplitude.

21. The spatial light modulator of claim 1, in which the spatial light modulator is used in transmission or in a reflective geometry.

23. The spatial light modulator of claim 1 being combined with an additional spatial light modulator adapted to modulate the phase of light interacting with the additional spatial light modulator.

24. A display device which includes the spatial light modulator of claim 1.

25. The display device of claim 24, in which the display device has up to several million pixels.

26. The display device of claim 24, in which the display device contains a diffuser foil.

27. The display device of claim 24, in which the display device is a 2D phase modulating display device or a stereoscopic display device or in which the display device is a holographic display device and in which the holographic display device preferably uses virtual observer windows for the eyes of the observer or observers.

29. Method of using a display device of claim 1, the display including a light source and an optical system to illuminate the spatial light modulator;

comprising the step of;

for each pixel, modulating the light field amplitude transmitted by each pixel using a surface relief grating which acts as a diffractive lens, where a material is used to fill the grooves of the surface grating structure, such that a controllable refractive index of the material inside the surface relief grating is controlled by an electric field.

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