  A generalized theory of spatial coherence for superposition of two speckle
patterns with polarization diversity is presented. The presented theory deals
with superposition in different scenarios i.e. superposition of two fully
correlated, partially correlated and completely uncorrelated speckle patterns,
and describes the effect on the spatial coherence-polarization (CP) property of
the superposed random field from the study of the spatial degree of coherence
and degree of polarization. The change in the spatial CP property with the
polarization diversity is studied for different correlation factors of the
constituent random fields, and a modulation of the spatial CP property is
observed, when the constituent speckle patterns are not fully correlated. The
effect of the average intensity ratio of the two random fields on the spatial
CP property is also studied. Thus, this theoretical study completes the case of
superposition of two speckle patterns with polarization diversity and its
effect on the spatial CP property.
