Optical film and process for manufacture thereof
Assignee3M Innovative Properties Company
InventorsWilliam W. Merrill, Richard C. Allen, Ronald J. Tabar, Peter D. Condo, Timothy J. Nevitt
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Abstract
Optical films and processes for forming the optical films are described in which materials having different properties are used and the different properties are exploited to obtain improved optical and/or mechanical properties of the optical film. The different properties of the materials may be used to select processing conditions under which the materials will react differently. The film may be processed with respect to two different directions with the amount of molecular orientation, if any, induced by the process being separately controlled for each material and each direction.
Claims26
A method of making an optical film comprising the step of drawing a film including a first and second material along first and second in-plane axes of the film under conditions which induce optical-orientation in at least the first material along the first in-plane axis of the film while inducing an orientation in the first material along the second in-plane axis of the film which is substantially less than the orientation induced in the first material along the first in-plane axis of the film such that a refractive index of the second material substantially matches a refractive index of the first material along one of the first and second in-plane axes of the film.
A method of fabricating an optical film comprising the steps of:
- providing a film including a first material and a second material optically interfaced with the first material, the first and second material having different visco-elasticity characteristics;
- drawing the film in a first direction under draw conditions selected to induce optical orientation of the first material in the first direction without inducing optical orientation of the second material;
- and
- drawing the film in a second direction under draw conditions selected to induce optical orientation of both the first and the second material.
A process for making a film having desired optical properties, the process comprising the steps of:
- (a) providing a film including a first material and a second material optically interfaced with the first material, the first and second material having different visco-elasticity characteristics;
- (b) processing the film to produce optical orientation of the first material in a first direction without inducing optical orientation of the second material in the first direction;
- and
- (c) processing the film to produce optical orientation of both the first and the second material in a second direction.
A method of fabricating a polarizing film having reduced angular dependence, the method comprising the steps of:
- forming a multilayer film including a first layer of material optically interfaced with a second layer of material, an isotropic index of refraction of the first layer being different than an isotropic index of refraction of the second layer, the multilayer film having a first and a second in-plane axis defining planes of the first and second layers, and a third axis orthogonal to the first and second in-plane axes along a thickness direction of the first and second layers;
- drawing the multilayer film in a direction of the first in-plane axis in a manner such that indices of refraction of the first layer along the first in-plane axis, the second in-plane axis and the third axis and an index of refraction of the second layer along the second in-plane axis remain substantially unchanged while an index of refraction of the second layer along the first in-plane axis is changed to a value substantially equal to the index of refraction of the first layer along the first in-plane axis;
- and
- drawing the multilayer film in a direction of the second in-plane axis in a manner such that indices of refraction of the first and second layer along the third axis are substantially equal.
Dependencies are inferred from the claim text.