A film construction having an input surface for receiving a visible light incident thereon and an output surface opposed to said input surface for outputting a part of the visible light incident on the input 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 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 partial reflection and partial transmission over the visible wavelength range 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; and wherein the microlayers are oriented such that, on average, the thinner ORUs are closer than the thicker ORUs to the output surface; the film construction being characterized in further comprising a first ultra-low index layer laminated on the input surface side of the plurality of microlayers and second ultra-low index layer laminated on the output surface side of the plurality of microlayers, wherein each of the first ultra-low index layer and the second ultra-low index layer is made from a ultra-low index material having a refractive index over visible wavelengths in a range from 1.1- 1.3, such that the plurality of microlayers is optically immersed in the ultra-low index material; wherein each of the first ultra-low index layer and the second ultra-low index layer has a roughened outer surface. 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 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 partial reflection and partial transmission over the visible wavelength range 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; and wherein the microlayers are oriented such that, on average, the thinner ORUs are closer than the thicker ORUs to the output surface; the film construction being characterized in further comprising a first ultra-low index layer laminated on the input surface side of the plurality of microlayers and second ultra-low index layer laminated on the output surface side of the plurality of microlayers, wherein each of the first ultra-low index layer and the second ultra-low index layer is made from a ultra-low index material having a refractive index over visible wavelengths in a range from 1.1- 1.3, such that the plurality of microlayers is optically immersed in the ultra-low index material; wherein each of the first ultra-low index layer and the second ultra-low index layer has a roughened outer surface.