LIGHT SOURCE INCORPORATING MULTILAYER OPTICAL FILM

摘要

A light source includes a lightguide having a top side comprising an optical film, a bottom side comprising a diffuse reflector, and an input side extending between the top and bottom sides. An illumination source is disposed proximate the input side of the lightguide. The optical film has adjacent first and second zones, each zone extending substantially an entire thickness of the optical stack or an entire thickness of at least one optical packet of the optical film. Light enters the lightguide from the light source propagating within the lightguide and being either reflected or transmitted by the optical film primarily by optical interference. For at least one first incidence angle and at least one wavelength, the first and second zones of the optical film have substantially equal optical transmittance. For at least one second incidence angle and at least one wavelength, the second zone has substantially greater optical transmittance than the first zone of the optical film.