Patent ID: 7425089
Filing Date: 2008-09-16
Classification: G02B,G02F

Abstract:
1. An illumination device, comprising: a light source; and a lightguide element including an incidence surface for receiving light emitted from the light source and an outgoing surface from which the light incident from the incidence surface goes out; wherein: the lightguide element includes a polarization selection layer for causing light of a specific polarization direction, among the light incident from the incidence surface, to selectively go out from the outgoing surface, and a polarization conversion layer for converting light of a polarization direction, different from the specific polarization direction, into the light of the specific polarization direction; the polarization selection layer reflects the light of the specific polarization direction substantially only toward the outgoing surface, and wherein at least part of the polarization conversion layer is substantially parallel to the polarization selection layer, and wherein the polarization conversion layer is a phase plate and is formed of a transparent material having birefringence, and wherein the polarization selection layer includes a plurality of inclining dielectric films provided at a predetermined angle with respect to the outgoing surface.