Patent ID: 6169613
Filing Date: 2001-01-02
Classification: G02B,G03H

Abstract:
A holographic optical device comprising: a light transmissive substrate; a first holographic optical element carried by said substrate; and a second holographic optical element carried by said substrate laterally of said first holographic optical element; wherein said first holographic optical element diffracts incident light into said substrate such that said light is trapped inside by internal reflection; and wherein said second holographic optical element diffracts said light out of said substrate; and wherein said light trapped inside said substrate undergoes multiple internal reflections, such that at least part of said light impinges more than once at different locations on at least one of said first and said second holographic optical elements; and wherein at least part of said light impinges at different angles of incidence on at least one of said different locations; and wherein said at least one of said first and said second holographic optical elements is constructed such that at said at least one of said different locations, it diffracts said light with significantly higher efficiency for one of said different angles of incidence than for any other angle of incidence.