Highly accurate calibration of a polarimeter of the type having at least four
detectors involves using four known states of polarisation of an input light signal
(calibration polarisations) and at least one further state of polarisation. All
input states of polarisation to the polarimeter have unity normalised power of
the light signal and unity degree of polarisation. A Stokes matrix for the four
calibration polarisations is generated with at least one variable correction parameter,
and a correction matrix is determined from the Stokes matrix and a corresponding
detector current matrix measured by the polarimeter. An optimisation criterion
that is a function of the degrees of polarisation for the states of polarisation
as measured by the polarimeter is generated. The correction parameter is varied
iteratively to minimise the optimisation criterion so that the polarimeter is calibrated
to produce unity power and degree of polarisation for any input state of polarisation.
