MULTILAYER OPTICAL FILM WITH OUTPUT CONFINEMENT IN BOTH POLAR AND AZIMUTHAL DIRECTIONS AND RELATED CONSTRUCTIONS

摘要

A film includes microlayers arranged into optical repeat units. Adjacent microlayers have in-plane refractive index mismatches &Dgr;nx, &Dgr;ny tailored to provide mirror-like on-axis properties, such that the film has a reflectivity for normally incident light in an extended wavelength band of at least 75% for any polarization. Adjacent microlayers also have a refractive index mismatch &Dgr;nz that provides the film with reduced reflectivity R1 and increased transmission for p-polarized light in the extended wavelength band incident on the film in a first plane of incidence at an angle &thetas;oblique, where R1 is no more than half of the minimum of on-axis reflectivity. Further, &Dgr;nx and &Dgr;ny are different enough so that for light 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 and incident at any angle.