  A complete single-point statistical description of a narrow-band partially
polarized optical field is developed in terms of the 2-D Period-Averaged
Probability Density Function (PA-PDF) of the electrical field vector. This
statistic can be measured using the coherent (heterodyne) detection. PA-PDF
carries more information about the partially-polarized light than the
traditional Stokes vector. For a simple Gaussian partially polarized field the
PA-PDF depends on 13 real parameters in contrast to the four parameters of the
Stokes vector or coherence tensor
