Polarization sensitive scattering element

• US 6,310,671 B1
• Filed: 03/30/1998
• Issued: 10/30/2001
• Est. Priority Date: 04/07/1995
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Larson, Brent D.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US09/052,821
• Time in Patent Office: 1,310 Days
• Field of Search: 349/86, 349/87, 349/96, 349/62, 349/67, 359/37, 359/63, 359/494, 359/487, 359/49, 359/51-53, 353/20
• US Class Current: 349/96
• CPC Class Codes: G02B 19/0047 for use with a light source G02B19/009, G02B19/0095 take precedence; details of lighting devices in general F21V; non-semiconductor lasers having optical devices external to the laser cavity H01S3/005
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 3/005 arranged along a single direction only, e.g. lenticular sheets G02B3/0043 takes precedence
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G02B 5/3008 comprising dielectric particles, e.g. birefringent crystals embedded in a matrix
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• 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: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 2203/03 scattering
• CPC Class Codes: G03B 21/604 Polarised screens

Abstract

A polarization-sensitive scattering element (PSSE) that acts to effectively separate light of different polarizations. The PSSE is a microstructural composite of material domains having differing birefringence. The PSSE has a first scattering distribution for light rays of a first polarization and a second scattering distribution for light rays of a second polarization. The first scattering distribution is such that the majority of the light rays of the first polarization are randomly backscattered. The second scattering distribution is such that the majority of the light rays of the second polarization are substantially transmitted. The PSSE provides a means for recapturing light energy which would otherwise be lost in display devices, while reducing degradation and heat build-up due to light absorption.

Claims

1. A polarizer, comprising:

a polarization-sensitive scattering element (PSSE), wherein said PSSE is a microstructural composite of material domains having differing birefringence and having a first scattering distribution for light rays of a first polarization and a second scattering distribution for light rays of a second polarization, wherein the first scattering distribution is such that the majority of the light rays of the first polarization are randomly backscattered.

2. The polarizer of claim 1, wherein the second scattering distribution is such that the light rays of the second polarization are substantially non-scattered.

3. The polatizer of claim 1, wherein the PSSE is a uniaxial homogeneously-aligned structure form from droplets made of liquid crystal embedded in polymer matrix, the droplets being physically stretched along a common axis, and refractive indices of the liquid crystal being selected such that either one of the ordinary index or extraordinary index of the liquid crystal matches the corresponding index of the polymer matrix.

4. The polarizer of claim 1, wherein the PSSE is a uniaxial homogeneously-aligned polymer dispered liquid crystal (PDLC) structure is back scattering for the first polarization.

5. The polarizer of claim 4, wherein the PDLC structure is formed from liquid crystal droplets aligned in a common direction by application of an electric field.

6. The polarizer of claim 4, wherein the PDLC structure is formed from liquid crystal droplets aligned in a common direction by application of an electro-magnetic field.

7. The polarizer of claim 4, wherein the PSSE is comprised of fibers aligned and embedded in a matrix, wherein the scattering profile of the PSSE is dependent upon the material refractive indexes, fiber diameter, and number of fibers.

8. The polarizer of claim 4, wherein the PSSE is comprised of a plurality of birefringement crystals aligned along an optical axis and embedded within a non-birefringement matrix.

9. The polarizer of claim 4, wherein a portion of the material domains are substantially non-birefringement.

10. The polarizer of claim 4, wherein the PSSE is a PDLC structure in which the liquid crystalline domains have been polymerized with an aligned orientation.

11. The polarizer of claim 1, wherein the PSSE is substantially backscattering for the first polarization and substantially transparent for a polarization orthogonal to the backscattering polarization.

12. The polarizer of claim 1, wherein the second scattering distribution is such that the majority of the light rays of the first polarization are transmitted.

13. The polarizer of claim 1, wherein the composite is comprised of at least two polymer types.

14. The polarizer of claim 1, wherein a portion of the material domains are substantially birefringent.

15. A polarization-sensitive scattering element (PSSE), comprising a microstructural composite of material domains having differing birefringence and having a first scattering distribution for light rays of a first polarization and a second scattering distribution for light rays of a second polarization, wherein the first scattering distribution is such that the light rays of the first polarization are randomly backscattered, and wherein the PSSE is comprised of fibers aligned and embedded in a matrix, wherein the scattering profile of the backscattered light is dependent upon the material refractive indexes, fiber diameter, and number of fibers.

16. A polarization-sensitive scattering element (PSSE), comprising a microstructural composite of material domains having differing birefringence and having a first scattering distribution for light rays of a first polarization and a second scattering distribution for light rays of a second polarization, wherein the first scattering distribution is such that the light rays of the first polarization are randomly diffuse, and wherein the PSSE is comprised of liquid crystal with alternating domains contained within, formed by locally polymerizing separate regions with a transverse aligning field selectively applied.

17. A backscattering diffuse polarizer, comprising a polarization-sensitive scattering element (PSSE), wherein said PSSE is a microstructural composite of material domains having differing birefringence, wherein the PSSE has a thickness and a difference in birefringence that are sufficient to randomly backscatter a majority of the light of a first polarization.

18. A polarization-sensitive scattering element (PSSE), comprising domains of a first polymer type and a second polymer type having birefringence, wherein a first refractive index of said domains of the first polymer type matches a second refractive index of said domains of the second polymer type, the birefringence of said domains of the first polymer type is different from the birefringence of said domains of the second polymer type such that a majority of light of a first polarization is backscattered and such that a majority of light of a second polarization is transmitted.