Single-layer reflective super broadband circular polarizer and method of fabrication therefor
First Claim
1. A broadband polarizer comprising a film of at least one material having a cholesteric order which includes sites of non-linearly varying helix pitch distributed across the thickness of said film and at least one liquid crystal material distributed across the thickness of said film and disposed at said sites said film having a given bandwidth.
2 Assignments
0 Petitions
Accused Products
Abstract
The present invention relates generally to broadband, reflective circular polarizers and, more particularly, to single layer super broadband, reflective circular polarizers. The polarizers of the present invention are made from a film of material, like a polymer having a cholesteric order, in which a second liquid crystal material, like a nematic liquid crystal, 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 polymer. The resulting polarizers have band passes approaching 2000 nm and reflect circularly polarized light which is either left-handed or right-handed depending on the final spiral structure of the materials utilized. The material of the present invention is fabricated by mixing commercially available polymers having a cholesteric order, a second liquid crystal material and a photoinitiator at a temperature which maintains the mixture in a liquid state. The polymer and the liquid crystal are present in a ratio by weight of 1:2, for example, and the photoinitiator is present in an amount of 0.6% by weight, for example, in the mixture. The heated mixture is then subjected to actinic radiation for a time and at an intensity sufficient to polymerize the polymer or the liquid crystal material or both. Under all polymerizing conditions the segregation rate of the liquid crystal material has to be greater than the polymerization rate of the material being polymerized. The liquid crystal segregates and diffuses, during polymerization, to sites of enlarged pitch in the polymer material from sites of shrunken pitch in the polymer material. Because the actinic light has an exponential intensity distribution due to light attenuation by, for example, light absorption, polymerization occurs in a non-linear fashion resulting in a non-linear distribution of the polymer and the liquid crystal material across the film.
125 Citations
68 Claims
- 1. A broadband polarizer comprising a film of at least one material having a cholesteric order which includes sites of non-linearly varying helix pitch distributed across the thickness of said film and at least one liquid crystal material distributed across the thickness of said film and disposed at said sites said film having a given bandwidth.
-
30. A method of fabricating a broadband polarizer comprising the step of:
converting a mixture of at least one material having a cholesteric order and sites of a given helix pitch and at least one liquid crystal material such that said at least one liquid crystal material having a cholesteric order is converted to a film wherein said sites of given helix pitch are changed to sites of nonlinearly varying helix pitch across the thickness of said film and wherein said at least one liquid crystal material is distributed across the thickness of said film and disposed at said sites of nonlinearly varying pitch. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
-
65. A single layer polarizer comprising:
a film of a first liquid crystal material and a second liquid crystal material, one of said materials having sites of nonlinearly varying helix pitch distributed across the thickness of said film the other of said materials being distributed across the thickness of said film and disposed at said sites.
-
66. A method of forming a single layer polarizer comprising the steps of:
forming a film from a first liquid crystal material and a second liquid crystal material, one of said materials having sites of nonlinearly varying helix pitch distributed across the thickness of said film the other of said materials being distributed across the thickness of said film and disposed at said sites.
-
67. A broadband polarizer comprising a film of at least one material having a cholesteric order which includes sites of nonlinearly varying helix pitch distributed across the thickness of said film and at least one liquid crystal material distributed across the thickness of said film and disposed at said sites at least one of said materials being unpolymerized, said film having a given bandwidth.
-
68. A broadband polarizer comprising a film of at least one material having a cholesteric order which includes sites of varying helix pitch distributed across the thickness of said film and at least one liquid crystal material distributed across the thickness of said film and disposed at said sites at least one of said materials being unpolymerized, said film having a given bandwidth.
Specification
-
- Resources
-
Current AssigneeReveo, Inc.
-
Original AssigneeReveo, Inc.
-
InventorsFaris, Sadeg Mustafa, Li, Le
-
Primary Examiner(s)Sikes, William L.
-
Assistant Examiner(s)Malinowski, Walter T.
-
Application NumberUS08/550,022Time in Patent Office757 DaysField of Search359/65, 359/37, 359/51, 359/52, 359/500, 359/490, 359/492, 252/299.7, 252/585, 349/98, 349/194US Class Current349/98CPC Class CodesB82Y 15/00 Nanotechnology for interact...E06B 2009/2464 featuring transparency cont...F24S 50/80 for controlling collection ...G02B 5/3016 involving passive liquid cr...Y02E 10/40 Solar thermal energy, e.g. ...
