Characterization of birefringent media via intrinsic and equivalent parameters

Birefringent media can be characterized through either their intrinsic parameters or their equivalent parameters, which are complementary. Commonly, some parameters are measured experimentally while others are derived via non-bijective relations, which can lead to ambiguous results and erroneous models of the medium. To address this issue, a physically grounded criterion is proposed, along with an experimental methodology for the independent and simultaneous measurement of both parameter sets. This approach resolves ambiguity by ensuring that only physically meaningful parameter values are determined. The validity of this method has been experimentally confirmed in several birefringent media.