Waveguide Comprising an Anisotropic Diffracting Layer

• US 20090074356A1
• Filed: 10/14/2005
• Published: 03/19/2009
• Est. Priority Date: 10/15/2004
• Status: Abandoned Application

• Current Assignee: DSM IP Assets BV (DSM-Firmenich AG), Stichting Dutch Polymer Institute
• Original Assignee: Stichting Dutch Polymer Institute
• Inventors: Escuti, Michael James, Sanchez, Carlos I., Broer, Dirk Jan, Bastiaansen, Cornelis Wilhelmus Maria, Van Heesch, Christianus Martinus
• Application Number:
  US11/665,071
• Publication Number:
  US 20090074356A1
• Time in Patent Office: Days
• US Class Current: 385/31
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02B 6/1221 made from organic materials
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• CPC Class Codes: G02B 6/126 using polarisation effects G02B6/1226 takes precedence

Abstract

The invention relates to an edge-lit slab waveguide equipped with a slanted anisotropic holographic layer, which couples out linearly polarized light. The invention further relates a new slanted anisotropic holographic layer suitable for use on the waveguide according to the invention, to a method to prepare such layer, and devices comprising the waveguide according to the invention.

Claims

1. Edge-lit slab waveguide equipped with a slanted anisotropic holographic layer which couples out linearly polarized light.

2. Waveguide according to claim 1, having a polarization contrast of at least 3.

3. Waveguide according to claim 1, wherein the light of different wavelengths (colors) is coupled out at different angles.

4. Waveguide according to claim 3 with a degree of polarization of at least 3 at all visible wavelengths.

5. Waveguide according to claim 1, wherein the light which is not outcoupled can be recycled.

10. Waveguide according to claim 1, comprising a slanted anisotropic holographic layer based on photo-polymerizable material and at least one mesogen in which the mesogen is in an aligned state after polymerization.

16. Waveguide according to claim 1, the difference between the ordinary refractive index of the mesogen (n_o,m) and the isotropic refractive index of the polymer (n_iso,p) being less than 0.03 in the state wherein polarized light is outcoupled or the difference between the extra-ordinary refractive index of the mesogen (n_e,m) and the isotropic refractive index of the polymer (n_iso,p) being less than 0.03 in the state wherein polarized light is outcoupled.

17. Waveguide according to claim 1 comprising at least one non-reactive mesogen, wherein the coating or layer is switchable between a light out-coupling (bright) state and a non-light-outcoupling (dark) state.

22. Frontlight comprising the waveguide according to claim 1.

23. Backlight comprising the waveguide according to claim 1.

24. Display comprising a waveguide according to claim 1.

25. Optical device comprising a waveguide according to claim 1.

6. Slanted anisotropic holographic layer based on photo-polymerizable material and at least one mesogen in which the mesogen is in an aligned state after polymerization.

7. Layer according to claim 6, wherein the layer is based on at least one reactive monomer and at least one non-reactive mesogen in which the mesogen is in an aligned state after polymerization of the monomer.

8. Layer according to claim 6, wherein the layer is based on at least one reactive monomer and at least one reactive mesogen in which the mesogen is in an aligned state after polymerization.

9. Layer according to claim 6, wherein the layer comprises at least one reactive monomer and a mixture of at least one reactive and at least one non-reactive mesogen which mesogens are in an aligned state after polymerization.

11. Edge-lit slab waveguide equipped with a slanted anisotropic holographic layer which couples out linearly polarized light, wherein the layer is obtained by polymerization of a mixture of at least one reactive monomer and a mesogen, and wherein the mesogen is in an aligned state.

12. Waveguide according to claim 11, wherein the mesogen comprises at least one compound having a polymerizable group.

13. Waveguide according to claim 11, wherein the reactive monomer comprises at least a polyfunctional acrylate or methacrylate compound.

14. Waveguide according to claim 11, wherein the mesogen comprises at least one compound having a cationically polymerizable group.

15. Waveguide according to claim 14, wherein the mesogen comprises at least one compound having an epoxy, oxetane or vinylether group.

18. Method for producing a slanted anisotropic holographic layer, based on at least one reactive monomer and at least one reactive mesogen which are polymerized by use of different polymerization methods.

19. Method according to claim 18, wherein the polymerization of the monomer is induced using a photo-initiator and UV light and in which the hologram is recorded in transmission mode.

20. Slanted anisotropic holographic layer obtainable by the method according to claim 18.

21. Edge-lit slab waveguide comprising a slanted anisotropic holographic layer according to claim 20.

26. Method for making a slanted anisotropic holographic layer comprising the steps of

a) providing a mixture of at least one reactive monomer and a reactive mesogen,

b) making a layer of the mixture,

c) applying UV radiation in order to at least partially polymerize the reactive monomer into a slanted transmission grating,

d) applying a subsequent thermal or UV exposure to further polymerize the reactive mesogen and (optional) residual unreacted monomer.

27. The method according to claim 26, wherein the UV radiation in step c is applied using a laserbeam split into a two beam transmission mode geometry.

28. The method according to claims 26, wherein the reactive monomer comprises at least a polyfunctional acrylate or methacrylate compound.

29. The method according to claim 26, wherein the reactive mesogen comprises at least a compound having a cationically polymerizable group.

30. The method according to claim 26, wherein the layer of the mixture is prepared by filling the mixture into a cell having one or more spacers of a defined thickness.