Patent ID: 8988776
Filing Date: 2015-03-24
Classification: B32B,G02B,G02F,Y10T

Abstract:
1. A reflective film having substantially flat outer surfaces, comprising: a plurality of microlayers arranged into optical repeat units for reflecting light over an extended wavelength band, adjacent microlayers exhibiting substantial in-plane refractive index mismatches Δnx along an x-axis and Δny along a y-axis, such that for normally incident light in the extended wavelength band, the film has a reflectivity Rnormalx for such light polarized along the x-axis and a reflectivity Rnormaly for such light polarized along the y-axis, Rnormalx and Rnormaly both being at least 75%; wherein adjacent microlayers also exhibit a substantial refractive index mismatch Δnz along an out-of-plane z-axis, such that for light in the extended wavelength band incident on the film in a first plane of incidence, the film has a reflectivity R1 of no more than half of Rnormalmin for such light that is p-polarized and incident at an angle θoblique, where Rnormalmin is the lesser of Rnormalx and Rnormaly; and wherein Δnx and Δny are different enough so that for light in the extended wavelength band incident on the film in a second plane of incidence orthogonal to the first plane, the film has a reflectivity R2 of at least 75% for such light that is p-polarized, for all angles of incidence.