APPLICATION OF THE HIGH-ACCURACY UNIVERSAL POLARIMETER TO MAGNETIC AND ABSORBING CRYSTALS

In this paper we show that the high-accuracy universal polarimeter can be used to investigate the optical properties of (almost) any crystal through which light can be transmitted. The only extra condition is t hat the reciprocal linear birefringence (or the reciprocal linear dich roism) of the sample is large with respect to the other optical effect s that are present. The sample is allowed to exhibit reciprocal linear birefringence and reciprocal circular birefringence. This is the situ ation for which the high-accuracy universal polarimeter was originally intended. We show, however, that reciprocal linear dichroism and reci procal circular dichroism may also be present. The method can, therefo re, be applied to (weakly) absorbing crystals. Furthermore, optical ef fects are taken into account that are related to the breaking of time- reversal symmetry. These are the non-reciprocal circular birefringence , non-reciprocal circular dichroism, non-reciprocal linear birefringen ce and non-reciprocal linear dichroism. This means that, under some co nditions, each (weakly) absorbing, magnetic crystal can be investigate d with the high-accuracy universal polarimeter. We derive a unified fo rmula for the intensity change of the light that propagates through th e polarimeter. This expression can be used to determine the (complex) eigenpolarizations of an arbitrary sample. Moreover, it is shown how t his unified formula can be translated to a formula in terms of the dif ferent birefringent and dichroic optical effects. The relevant formula for a specific case can, therefore, be given directly. The method is demonstrated by means of measurements on samples of NiSO4 . 6H(2)O. Th is material shows reciprocal linear birefringence, reciprocal linear d ichroism, reciprocal circular birefringence and reciprocal circular di chroism, simultaneously.