Method for measuring the phase shift introduced by a phase plate with an interference ellipsometer

A new method for measuring the phase delay introduced by a phase plate is substantiated. The method uses an interference ellipsometer that does not require preliminary determination of the direction of the principal axes of the plate. Sources of error in the method are analyzed and components of error are quantitatively estimated. Requirements for the polarization characteristics of a beamsplitter used in the interference ellipsometer are formulated and conditions for decreasing the measurement error are found.