Characterization of the birefringence of materials offers the opportunity to develop applications and elements to manipulate the polarization of light. We propose a new method for characterizing the effective phase retardation based on the linear birefringent law. The proposed method is flexible and easy to implement; it also determines the retardation introduced by a linear birefringent as from an input polarization state and a specific output state generated by the rotated material. The method is evaluated experimentally by characterizing the birefringence of cellophane samples.
