Polarizing beam splitter
First Claim
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1. A polarizing beam splitter comprising:
- (a) a birefringent film comprising a plurality of first material layers and a plurality of second material layers, wherein the first material layers comprise a polymer selected from a group consisting of polyethylene terephthalate and copolymers of polyethylene terephthalate and polyethylene naphthalate and the second material layers comprise a copolyester comprising, as comonomer subunits, 1,4-dimethylterephthalate, 1,2-ethane diol, 1,4-dimethylcyclohexane dicarboxylate, and 1,4-cyclohexane dimethanol; and
(b) at least one prism comprising a base adjacent a first major surface of the birefringent film, wherein the at least one prism comprises a refractive index greater than 1.6.
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Abstract
The present invention provides a unique polarizing beam splitter (PBS) that is suitable for use in projection systems and displays. The PBS contains at least one prism having at least one major surface and having a refractive index of at least about 1.6 and a birefringent film disposed on the major surface of the prism. The birefringent film is a multi-layer film having at layers of at least a first material and a second material. After uniaxial stretching, the film exhibits a refractive index difference of less than about 0.15 units in the stretched direction.
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23 Claims
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1. A polarizing beam splitter comprising:
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(a) a birefringent film comprising a plurality of first material layers and a plurality of second material layers, wherein the first material layers comprise a polymer selected from a group consisting of polyethylene terephthalate and copolymers of polyethylene terephthalate and polyethylene naphthalate and the second material layers comprise a copolyester comprising, as comonomer subunits, 1,4-dimethylterephthalate, 1,2-ethane diol, 1,4-dimethylcyclohexane dicarboxylate, and 1,4-cyclohexane dimethanol; and
(b) at least one prism comprising a base adjacent a first major surface of the birefringent film, wherein the at least one prism comprises a refractive index greater than 1.6. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 22, 23)
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- 13. A multi-layer film comprising a plurality of first material layers and a plurality of second material layers, wherein the first material layers comprise a polymer selected from a group consisting of polyethylene terephthalate and copolymers of polyethylene terephthalate and polyethylene naphthalate and the second material layers comprise a copolyester comprising, as comonomer subunits, 1,4-dimethylterephthalate, 1,2-ethane diol, 1,4-dimethylcyclohexane dicarboxylate, and 1,4-cyclohexane dimethanol.
Specification