Patent ID: 8289639

Claim:
An optical film structure, comprising: a first film comprising a first smooth side; and a first structured side opposite the first smooth side, the first structured side comprising a plurality of first linear prisms, each first linear prism formed by a first near surface and a first far surface, each first linear prism having a first peak at the intersection of the first near surface and the first far surface, the plurality of first peaks forming a first imaginary plane; wherein the first near surface forms an angle with the first imaginary plane between 35 and 55 degrees; and wherein the first far surface forms an angle with the first imaginary plane between 35 and 55 degrees; and a second film adjacent and parallel to the first film comprising a second smooth side facing the first structured side; and a second structured side opposite the second smooth side, the second structured side comprising a plurality of second linear prisms, each second linear prism formed by a second near surface and a second far surface, each second linear prism having a second peak at the intersection of the second near surface and the second far surface, the plurality of second peaks forming a second imaginary plane; wherein the second near surface forms an angle with the second imaginary plane between 70 and 110 degrees; and wherein the second far surface forms an angle with the second imaginary plane between 35 and 55 degrees.