Abstract: An optical film includes a layer of simultaneous biaxially stretched polyolefin film that is substantially non-absorbing and non-scattering for at least one polarization state of visible light. The layer has x, y, and z orthogonal indices of refraction where at least two of the orthogonal indices of refraction are not equal. The layer has an in-plane retardance of 100 nm or less and an absolute value of an out-of-plane retardance being 55 nm or greater.

Abstract: A process for making an optical film includes stretching a polyolefin film in a first direction and stretching the polyolefin film in a second direction different than the first direction forming a biaxially stretched polyolefin film. At least a portion of the stretching of the polyolefin film in the second direction occurs simultaneous with the stretching of the polyolefin film in the first direction. The biaxially stretched polyolefin film has a length and a width and substantially non-absorbing and non-scattering for at least one polarization state of visible light. The biaxially stretched polyolefin film has x, y, and z orthogonal indices of refraction where at least two of the orthogonal indices of refraction are not equal, an in-plane retardance being 100 nm or less and an out-of-plane retardance being 50 nm or greater.

Abstract: A process for making an optical film includes stretching a polyolefin film in a first direction and stretching the polyolefin film in a second direction different than the first direction forming a biaxially stretched polyolefin film. At least a portion of the stretching of the polyolefin film in the second direction occurs simultaneous with the stretching of the polyolefin film in the first direction. The biaxially stretched polyolefin film has a length and a width and substantially non-absorbing and non-scattering for at least one polarization state of visible light. The biaxially stretched polyolefin film has x, y, and z orthogonal indices of refraction where at least two of the orthogonal indices of refraction are not equal, an in-plane retardance being 100 nm or less and an out-of-plane retardance being 50 nm or greater.

Abstract: An optical stack includes a first liquid crystal layer and a j-retarder disposed on the liquid crystal layer. The j-retarder includes a simultaneous biaxially stretched polymeric film being substantially non-absorbing and non-scattering for at least one polarization state of visible light. The j-retarder has x, y, and z orthogonal indices of refraction where at least two of the orthogonal indices of refraction are not equal, an in-plane retardance being 100 nm or less and an absolute value for an out-of-plane retardance being 55 nm or greater.

Abstract: A method of stretching films in which all or a portion of the width of the film is cooled during or just after stretching so as to improve the uniformity of the film. The includes stretching a polymeric film in a tenter that grasps the film with a plurality of clips along the opposing edges of the film and propels the clips to thereby stretch the film. The tenter includes driven clips and idler clips, with at least one idler clip between respective pairs of driven clips. The cooling is done so as to improve the uniformity of the clip spacing relative to the spacing obtained at otherwise identical process conditions without such cooling.

Abstract: An optical film includes a layer of simultaneously biaxially stretched polyolefin film that is substantially non-absorbing and non-scattering for at least one polarization state of visible light. The layer has x, y, and z orthogonal indices of refraction where at least two of the orthogonal indices of refraction are not equal. The layer has an in-plane retardance of 100 nm or less and an out-of-plane retardance of 50 nm or greater.