Patent ID: 6917427

Claim:
A method of calibrating a polarimeter of the type having at least four detectors, each detector generating a detector current which is related to a Stokes parameter in response to a light signal input to the polarimeter, comprising the steps of: inputting a plurality of different states of polarisation of the light signal to the polarimeter, each state of polarisation having a same power and degree of polarisation; measuring the detector currents for each of at least four of the different states of polarisation designated as calibration polarisations to form a current matrix for a Stokes matrix of the related Stokes parameters, at least one of the Stokes parameters including a correction parameter; determining a correction matrix from the detector currents and the Stokes matrix for the calibration polarisations; measuring the detector currents for at least one further state of polarisation designated as an auxiliary polarisation to determine the degree of polarisation for the auxiliary polarisation; and optimising a quality criterion by iteratively varying the correction parameter and repeating the above steps until the quality criterion is a minimum, the quality criterion being a function of the degree of polarization for the auxiliary polarisation.