Patent ID: 7145727
Filing Date: 2006-12-05
Classification: G02B

Abstract:
1. A unpolarized beam splitter (UBS) comprising an internal beam-splitting coating that is approximately symmetrical, wherein a beam of light will see about the same layer structure whether it is incident from a front side or a rear side of said coating, wherein said coating is designed to approximate the condition such that wherein Ψ S R −Ψ S R′ =Ψ PR −Ψ PR′ wherein Ψ PR is the phase introduced by said UBS for S-polarized light reflected from said front side, wherein Ψ S R′ is the phase introduced by said UBS for S-polarized light reflected from said rear side, wherein Ψ PR is the phase introduced by said UBS for P-polarized light reflected from said front side, and wherein Ψ PR′ is the phase introduced by said UBS for P-polarized light reflected from said rear side.