We study the angular structure of polarization of light transmitted through a nematic liquid crystal cell by analyzing the polarization state as a function of the incidence angles. Theoretical results are obtained by evaluating the Stokes parameters that characterize the polarization of plane waves propagating through the cell at varying direction of incidence. Using the Stokes polarimetry technique we measured the polarization resolved conoscopic patterns emerging after the homeotropically aligned nematic cell illuminated by, the convergent light beam. The resulting polarization resolved angular patterns are described in terms of the polarization singularities such as C-points and L-lines.