Topological structure of the polarization resolved conoscopic patterns, calculated theoretically and measured
experimentally for nematic liquid crystal (NLC) cells, is described in terms of polarization singularities, saddle
points and bifurcation lines. The parametric dynamics of the topological network, induced by the variation of the
incident light ellipticity, is analyzed for the nematic cells with uniform and non-uniform director configuration.
Different stages of similar dynamics are observed for homeotropically oriented NLC cell. Non-uniform director
configuration within the cell results in broken central symmentry in the arrangement of the topological network.
Main features of the experimentally obtained polarization resolved conoscopic patterns are the same to the
theoretically predicted ones.
We study the angular structure of polarization of light transmitted through a nematic liquid crystal (NLC) cell
by analyzing the polarization state as a function of the incidence angles. Our theoretical results are obtained
by evaluating the Stokes parameters that characterize the polarization state of plane waves propagating through
the NLC layer at varying direction of incidence. Using the Stokes polarimetry technique we carried out the
measurements of the polarization resolved conoscopic patterns emerging after the homeotropically aligned NLC
cell illuminated by the convergent light beam. The resulting polarization resolved angular patterns are described
both theoretically and experimentally in terms of the polarization singularities such as C-points (points of
circular polarization) and L-lines (lines of linear polarization). When the ellipticity of the incident light varies,
the angular patterns are found to undergo transformations involving the processes of creation and annihilation
of the C-points.