Circularly polarizing reflective material having super broad-band reflection and transmission characteristics and method of fabricating and using same in diverse applications

• US 6,181,395 B1
• Filed: 08/03/1999
• Issued: 01/30/2001
• Est. Priority Date: 11/27/1991
• Status: Expired due to Fees

• Current Assignee: Reveo, Inc.
• Original Assignee: Reveo, Inc.
• Inventors: Faris, Sadeg M., Li, Le, Jiang, Yingqiu
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): MALINOWSKI, WALTER J
• Application Number:
  US09/366,385
• Time in Patent Office: 546 Days
• Field of Search: 252/299.7, 252/585, 359/490, 359/492, 359/500, 349/98, 349/194
• US Class Current: 349/98
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: C09B 67/0098 Organic pigments exhibiting interference colours, e.g. nacrous pigments
• CPC Class Codes: C09D 11/037 characterised by the pigment
• CPC Class Codes: C09D 11/17 characterised by colouring agents
• CPC Class Codes: C09K 19/00 Liquid crystal materials
• CPC Class Codes: C09K 19/52 characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
• CPC Class Codes: E06B 2009/2464 featuring transparency control by applying voltage, e.g. LCD, electrochromic panels
• CPC Class Codes: E06B 9/24 Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blindsoperating, guiding or securing devices or arrangements for roll-type closures E06B9/56; free-hanging flexible screens A47H23/00
• CPC Class Codes: F24S 50/80 for controlling collection or absorption of solar radiation
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers

Abstract

Disclosed are super broadband circularly polarizing film materials and novel methods of fabricating and using the same. The circularly polarizing materials are made from polymerizable CLC film material having a cholesteric order, in which a liquid crystal material, such as a nematic liquid crystal material, is distributed in a non-linear fashion across the thickness of the film in a plurality of liquid crystal-rich and liquid crystal-depleted sites in the CLC polymer. The pitch of the helices of the CLC molecules in the polyermized CLC material varies in a non-linear (e.g. exponential) manner along the depth dimension (i.e. transverse to the surface) thereof. The resulting circularly polarizing materials have reflection and transmission characteristics over bands of operation approaching 2000 nm. Depending on the final spiral structure of the polymeriable CLC materials utilized, the CLC circularly polarizing materials reflect either left-handed or right-handed circularly polarized light. The CLC circularly polarizing materials of the present invention can be used in a variety of applications.

Claims

1. A broad-band reflective polarizer for selectively reflecting electromagnetic radiation having a first circular polarization state and wavelengths over a broad-band, and transmitting electromagnetic radiation having a second circular polarization state and wavelengths over said broad-band, said broadband reflective polarizer comprising:

a film formed from at least one material having a cholesteric order and sites of non-linearly varying pitch across the thickness of said film; and

at least one liquid crystal material non-linearly distributed across the thickness of said film and disposed at said sites.

2. The broad-band reflective polarizer according to claim 1, wherein said non linearly varying pitch is an exponentially varying pitch.

3. The broad-band reflective polarizer according to claim 1, wherein said material having a cholesteric order is a polymer.

4. The broad-band reflective polarizer according to claim 1, wherein said material having a cholesteric order is a monomer.

5. The broad-band reflective polarizer according to claim 1, wherein said material having a cholesteric order is an oligomer.

6. The broad-band reflective polarizer according to claim 1, wherein said at least one said liquid crystal material is a nematic liquid crystal.

7. The broad-band reflective polarizer according to claim 1, wherein said at least one liquid crystal material is a smectic liquid crystal.

8. The broad-band reflective polarizer according to claim 1, wherein said at least one material having a cholesteric order is photopolymerizable.

9. The broad-band reflective polarizer according to claim 1, wherein said at least one liquid crystal material is photopolymerizable.

10. The broad-band reflective polarizer according to claim 1, wherein at least one of said at least one material having a cholesteric order and said at least one liquid crystal material is polymerizable.

11. The broad-band reflective polarizer according to claim 1, wherein the segregation rate of said at least one liquid crystal material is greater than the polymerization rate of whichever of said materials is polymerized.

12. The broad-band reflective polarizer according to claim 1, wherein the segregation rate of said at least one liquid crystal material, is greater than the polymerization rate of said at least one material having a cholesteric order.

13. The broad-band reflective polarizer according to claim 1, wherein the segregation rate of said at least one liquid crystal material is greater than the polymerization rate of said material having a cholesteric order.

14. The broad-band reflective polarizer according to claim 1, wherein said at least one material having a cholesteric order is a cholesteric liquid crystal.

15. The broad-band reflective polarizer according to claim 1, wherein said at least one material having a cholesteric order is a cyclic liquid crystal siloxane.

16. The broad-band reflective polarizer according to claim 1, wherein said at least one material having a cholesteric order is a material which is polymerized by cationic polymerization.

17. The broad-band reflective polarizer according to claim 1, wherein said at least one liquid crystal material is a material which is polymerized by cationic polymerization.

18. The broad-band reflective polarizer according to claim 1, wherein said at least one liquid crystal material is a low molecular weight material.

19. The broad-band reflective polarizer according to claim 1, wherein said film has a thickness sufficient to totally reflect incident circularly polarized electromagnetic radiation.

20. The broad-band polarizer according to claim 19, wherein said film is a single layer.

21. The broad-band reflective polarizer according to claim 1, wherein said film reflects incident circularly polarized electromagnetic radiation in the visible spectrum.

22. The broad-band reflective polarizer according to claim 1, wherein said film reflects incident circularly polarized electromagnetic radiation in the infrared portion of the electromagnetic spectrum.

23. The broad-band reflective polarizer according to claim 1, wherein said film reflects incident circularly polarized electromagnetic radiation in the ultraviolet portion of the electromagnetic spectrum.

24. The broad-band reflective polarizer according to claim 1, wherein at least one of said at least one material having a cholesteric order and said at least one liquid crystal material is in the liquid state.

25. The broad-band reflective polarizer according to claim 1, wherein at least one of said at least one material having a cholesteric order and said at least one liquid crystal material is in the solid state.