Abstract: Disclosed herein is an optical device including a light source and an optical article. The optical article includes a lightguide and a viscoelastic layer disposed on the lightguide. Light emitted by the light source enters the lightguide and is transported within the lightguide by total internal reflection. The viscoelastic layer manages light, for example, at least about 50%, or less than about 10%, of light that enters the lightguide may be extracted. The optical device can be used in a variety of constructions for signs, markings, display devices, keypad assemblies, tail light assemblies and illumination devices.

Abstract: An optical stack (400) having a plurality of alternating polymeric layers (401, 402) is described. The alternating layers may be alternating birefringent (syndiotactic polystyrene, sPS) and isotropic (CoPENa) layers, or alternating positively and negatively birefringent layers. Birefringent layers are made using polymers which form optically symmetrical crystallites upon stretching of the polymer. The optical stack has a large refractive index difference in the x-direction (the stretching direction) and small refractive index differences in the y- and z-directions (the non-stretching directions). The optical stack can be made using standard film tentering methods and may be a multilayer reflective polarizer.

Abstract: An optical element includes an optical anisotropic medium. A difference between a minimum refractive index nl and a maximum refractive index nh of the optical anisotropic medium at a used central wavelength is at least 0.1, and a refractive index nt1 of a first medium optically adjacent to the optical anisotropic medium at the used central wavelength satisfies the following condition: (nt1?nl)·(nt1?nh)?0.

Abstract: An optical element including a first layer (011) made of a medium having optical anisotropy, wherein a difference between refractive indexes nh and nl (nh>nl) at a central wavelength ? for first and second polarized lights which enter the optical element and whose polarization directions are different from each other is at least 0.1, and wherein conditions (nt1?nl)·(nl?nt2)?0 and nt1<nl are satisfied, where nt1 and nt2 denote refractive indexes of a second layer (012) and a third layer (013) optically adjacent to the first layer in both sides of the first layer and made of isotropic media at the central wavelength.

Abstract: A circular polarizer comprising a single linear polarizer producing a linear state of polarization and at least one phase retardation film layered with the single linear polarizer. In a first embodiment, the at least one phase retardation film includes at least one uniaxial A-plate phase retardation film and at least one uniaxial C-plate phase retardation film. In a second embodiment of the invention, the circular polarizer includes a linear polarizer and at least one biaxial phase retardation film layered with the linear polarizer. In another example of the circular polarize of the second embodiment, at least one uniaxial A-plate phase retardation film and/or at least one uniaxial C-plate phase retardation film is also layer with the linear polarize and the biaxial phase retardation film.

Abstract: An optical element including a first layer (011) made of a medium having optical anisotropy, wherein a difference between refractive indexes nh and nl (nh>nl) at a central wavelength ? for first and second polarized lights which enter the optical element and whose polarization directions are different from each other is at least 0.1, and wherein conditions (nt1?nl)·(nl?nt2)?0 and nt1<nl are satisfied, where nt1 and nt2 denote refractive indexes of a second layer (012) and a third layer (013) optically adjacent to the first layer in both sides of the first layer and made of isotropic media at the central wavelength.