  We present a technique for studying the polarimetric properties of a
birefringent object by means of classical ghost diffraction. The standard ghost
diffraction setup is modified to include polarizers for controlling the state
of polarization of the beam in various places. The object is characterized by a
Jones matrix and the absolute values of the Fourier transforms of its
individual elements are measured. From these measurements the original
complex-valued functions can be retrieved through iterative methods resulting
in the full Jones matrix of the object. We present two different placements of
the polarizers and show that one of them leads to better polarimetric quality,
while the other placement offers the possibility to perform polarimetry without
controlling the source's state of polarization. The concept of an effective
source is introduced to simplify the calculations. Ghost polarimetry enables
the assessment of polarization properties as a function of position within the
object through simple intensity correlation measurements.
