Beam splitter designs for interferometers provide a phase difference between the two resulting interference beams that are independent of the polarization status of the incident beam. The polarization independent phase coating is achieved by making the internal beam splitting coating of an unpolarized beam splitter to be symmetrical. A symmetrical coating will produce the phase matching condition, .PSI.S.sub.R-.PSI.S.sub.R'=.PSI..sub.PR-.PSI..sub.PR'=0.