Rheological measurements can be combined with various physical methods that are
especially important for the study of structural transformations caused by deformation.
Here it is important to utilize optical methods in various ranges of frequency. These methods
permit direct observation of characteristics of fluid flow by tracing particles in a
stream to measure velocity fields. Of particular interest is a measurement of double refraction
or birefringence during flow, since dynamic anisotropy of optical properties is
directly related to the material stress state. The use of other physical methods such as, for
example, X-ray analysis, neutron scattering, calorimetry, and others along with rheometry
is also of special interest.