The present invention relates to a method for determining a polarization dependent characteristic of an optical or opto-electronic device. Using the Mueller matrix data, a matrix M corresponding to a difference between a first and a second transmission spectrum is determined. The first and the second transmission spectrum correspond to a first Stokes vector and a second Stokes vector, respectively, with the second Stokes vector being opposite to the first Stokes vector. Eigenvalues of the matrix M are then determined and the first Stokes vector is determined by selecting the largest eigenvalue of the matrix M and determining a corresponding eigenvector. The second Stokes vector is then determined as a vector opposite to the first Stokes vector. Finally, the data indicative of the polarization dependent characteristic of the device are determined using the first and the second Stokes vector and the Mueller matrix data. This method is highly beneficial by providing highly accurate data related to polarization dependent parameters while simultaneously providing a nearly instantaneous result with minimum computational effort.