Optical film, reflective polarizer, optical stack, and optical construction

An optical film comprising a plurality of polymeric microlayers numbering at least 10 in total and disposed between, and co-extruded and co-stretched with, opposing first and second polymeric skins, each of the polymeric microlayers having an average thickness of less than about 400 nanometers (nm), each of the first and second polymeric skins having an average thickness of greater than about 1 micron, such that at least one of the first and second polymeric skins comprises a plurality of polymeric skin layers, each of the polymeric skin layers having an average thickness of greater than about 0.5 microns, the plurality of polymeric skin layers comprising a polymeric second skin layer disposed between polymeric first and third skin layers, wherein the polymeric second skin layer comprises one or more of a greater degree of crystallinity, a greater glass transition temperature, a greater modulus, and a greater in-plane birefringence than each of the polymeric first and third skin layers.