Geometrical representation of a monochromatic electromagnetic wave using the tangential vector approach

The aim of this work is to develop a coherent polarimetric model and to find a geometrical description of a monochromatic wave. The spinor form of the electrical field, its links to the coherency matrix and the Poincare' sphere are introduced with the aim to obtain a geometrical representation of the spinor. It consists, from the "polarization point of view", on the polarization vector and a tangential plane to the Poincare' sphere where it is possible to visualize the zero phase.