Patent ID: 9057843
Filing Date: 2015-06-16
Classification: G02B,G02F

Abstract:
1. A film construction having an input surface and an output surface, comprising: a plurality of microlayers arranged into optical repeat units (ORUs) to selectively reflect light by constructive or destructive interference, the microlayers having a greater reflectivity for normally incident light polarized along a first axis than for normally incident light polarized along a second axis, the first and second axes defining a film plane; wherein the microlayers are optically immersed in a medium having a refractive index greater than air, such that supercritical light can propagate through the plurality of microlayers; wherein the ORUs have a layer thickness distribution along a thickness axis perpendicular to the film plane, the layer thickness distribution having an average thickness and being effective to provide the plurality of microlayers with an intermediate reflectivity over an extended reflection band for a given incidence condition, the ORUs comprising thinner ORUs whose thicknesses are less than the average thickness, and thicker ORUs whose thicknesses are greater than the average thickness; wherein the microlayers are oriented such that, on average, the thinner ORUs are closer than the thicker ORUs to the output surface; and wherein the reflectivity for normally incident light polarized along the first axis is R1 over visible wavelengths and the reflectivity for normally incident light polarized along the second axis is R2 over visible wavelengths, and wherein R1 is at least 50% and R2 is at least 10%.