Patent ID: 8651726
Filing Date: 2014-02-18
Classification: G02B

Abstract:
1. An illumination system for use with an electronic display system, the illumination system comprising: an optical waveguide having a near end and a reflecting far end, a thickness of the waveguide at the reflecting end greater than a thickness at the near end, the waveguide further comprising an exit surface extending between the near and far ends and having a critical angle above which light rays may exit the waveguide; at least one dichroic layer located on the exit surface of the waveguide, the at least one dichroic layer configured to transmit exiting light rays having a first polarization and to reflect exiting light rays having a second polarization, different than the first polarization; and a polarization conversion film located on a surface of the waveguide opposite the exit surface, the polarization conversion film configured to transform the polarization of at least some of the exiting light rays having the second polarization reflected by the at least one dichroic layer to transformed light rays having the first polarization, and to reflect the transformed light rays having the first polarization back into the waveguide such that at least a portion of the transformed light rays having the first polarization may exit the waveguide and pass through the at least one dichroic layer.