Optical bodies made with a birefringent polymer
First Claim
1. A multilayer optical body, comprising:
- a plurality of birefringent first optical layers, each first optical layer comprising a copolymer of polyethylene naphthalate with less than 70 mol % of the carboxylate subunits of the copolymer being naphthalate subunits; and
a plurality of second optical layers interleaved with the first optical layers, the second optical layers having a lower in-plane birefringence than the first optical layers for 632.8 nm light.
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Abstract
A optical body has at least two polymeric materials forming a reflective interface for at least one polarization of light. One optical body is a multilayer optical film that includes birefringent first optical layers and second optical layers interleaved with the first optical layers. Each first optical layer is formed using a polymer, such as a copolymer of polyethylene naphthalate. The second optical layers are formed so that they have a lower in-plane birefringence than the first optical layers for 632.8 nm light. Optical bodies can be used as, for example, polarizers and mirrors. The optical bodies can be formed using polymers that provide better index matching and are more easily protected from UV light without coloring the optical body.
150 Citations
19 Claims
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1. A multilayer optical body, comprising:
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a plurality of birefringent first optical layers, each first optical layer comprising a copolymer of polyethylene naphthalate with less than 70 mol % of the carboxylate subunits of the copolymer being naphthalate subunits; and
a plurality of second optical layers interleaved with the first optical layers, the second optical layers having a lower in-plane birefringence than the first optical layers for 632.8 nm light. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A multilayer optical body, comprising:
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a plurality of birefringent first optical layers, each first optical layer comprising a polymer configured so as to yield an in-plane birefringence of at least about 0.16 at 632.8 nm after orientation at a temperature that is about the glass transition temperature of the polymer or lower; and
a plurality of second optical layers interleaved with the first optical layers, wherein the second optical layers have a lower in-plane birefringence than the first optical layers for 632.8 nm light. - View Dependent Claims (12, 13, 14, 15)
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16. A multilayer optical body, comprising:
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a plurality of birefringent first optical layers, each first optical layer comprising a copolymer of polyethylene naphthalate having. no more than about 20% crystallinity as determined using differential scanning calorimetry; and
a plurality of second optical layers interleaved with the first optical layers, the second optical layers having a lower in-plane birefringence than the first optical layers for 632.8 nm light. - View Dependent Claims (17, 18)
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19. A multilayer optical body, comprising:
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a plurality of polymeric first optical layer, each first optical layer having an optical efficacy of no more than about 0.10, and wherein each of the first optical layers comprises a copolymer of polyethylene naphthalate; and
a plurality of polymeric second optical layers interleaved with the first optical layer, the second optical layers having a lower in-plane birefringence than the first optical layers for 632.8 nm light.
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Specification