Abstract:
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 that
the reciprocal linear birefringence (or the reciprocal linear dichroism)
of the sample is large with respect to the other optical effects that are
present. The sample is allowed to exhibit reciprocal linear birefringence
and reciprocal circular birefringence. This is the situation for which
the high-accuracy universal polarimeter was originally intended. We show,
however, that reciprocal linear dichroism and reciprocal circular dichroism
may also be present. The method can, therefore, be applied to (weakly)
absorbing crystals. Furthermore, optical effects 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 birefringence and non-reciprocal linear dichroism.
This means that, under some conditions, each (weakly) absorbing, magnetic
crystal can be investigated with the high-accuracy universal polarimeter.
We derive a unified formula for the intensity change of the light that
propagates through the polarimeter. This expression can be used to determine
the (complex) eigenpolarizations of an arbitrary sample. Moreover, it is
shown how this unified formula can be translated to a formula in terms
of the different 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 NiSO4.6H2O.
This material shows reciprocal linear birefringence, reciprocal linear
dichroism, reciprocal circular birefringence and reciprocal circular dichroism,
simultaneously.