High efficiency optical devices
First Claim
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1. A backlight assembly, comprising:
- a light guide comprising opposing optical surfaces, wherein at least a portion of the opposing optical surfaces comprises a multilayer optical film that comprises alternating layers of at least two materials, wherein the multilayer optical film reflects light over a wavelength band of interest as a function of thicknesses of the alternating layers, wherein at least one of the materials has a stress induced birefringence, and further wherein at least one opposing optical surface comprises a plurality of voids formed in the multilayer optical film; and
at least one light source positioned between the opposing optical surfaces, wherein at least one void of the plurality of voids is capable of transmitting light emitted by the at least one light source.
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Abstract
Optical devices such as backlight assemblies, according to the present invention include a multilayer optical film in which at least one of the layers comprises an oriented birefringent polymer. The multilayer optical film exhibits low absorptivity and can reflect light approaching at shallow angles as well as normal to the film.
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Citations
19 Claims
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1. A backlight assembly, comprising:
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a light guide comprising opposing optical surfaces, wherein at least a portion of the opposing optical surfaces comprises a multilayer optical film that comprises alternating layers of at least two materials, wherein the multilayer optical film reflects light over a wavelength band of interest as a function of thicknesses of the alternating layers, wherein at least one of the materials has a stress induced birefringence, and further wherein at least one opposing optical surface comprises a plurality of voids formed in the multilayer optical film; and at least one light source positioned between the opposing optical surfaces, wherein at least one void of the plurality of voids is capable of transmitting light emitted by the at least one light source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A backlight assembly, comprising:
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a light guide comprising opposing optical surfaces and an opening substantially orthogonal to the opposing optical surfaces, wherein at least a portion of the opposing optical surfaces comprises a multilayer optical film that comprises alternating layers of at least two materials, wherein the multilayer optical film reflects light over a wavelength band of interest as a function of thicknesses of the alternating layers, wherein at least one of the materials has a stress induced birefringence, and further wherein at least one opposing optical surface comprises a plurality of voids formed in the multilayer optical film; and at least one light source positioned proximate the opening, wherein at least one void of the plurality of voids is capable of transmitting light emitted by the at least one light source. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification