US 5,882,774 A · Optical film

Abstract

Birefringent multilayer optical films in which the refractive indices in the thickness direction of two adjacent layers are substantially matched have a Brewster angle (the angle at which reflectance of p-polarized light goes to zero) which is very large or is nonexistant. This allows for the construction of multilayer mirrors and polarizers whose reflectivity for p-polarized light decreases slowly with angle of incidence, are independent of angle of incidence, or increase with angle of incidence away from the normal. As a result, multilayer films having high reflectivity (for both planes of polarization for any incident direction in the case of mirrors, and for the selected direction in the case of polarizers) over a wide bandwidth, can be achieved.

Claims45

Dependent claims

A film, comprising:

a first layer comprising a first polymeric material;
and
a second layer, contiguous to said first layer, comprising a second polymeric material;
wherein the absolute value of the difference in indices of refraction between said first and second layers is .DELTA.x, .DELTA.y, and .DELTA.z, respectively, for light polarized along first, second, and third mutually orthogonal axes, wherein said third axis is orthogonal to the plane of said film, wherein .DELTA.x is greater than about 0.05, and wherein .DELTA.z is less than about 0.05.

1 more element

Dependencies are inferred from the claim text.

Optical film

Life of this patent

Optical film

Life of this patent

Abstract

Claims45