Differential speckle polarimetry with SCExAO VAMPIRES

Abstract. The differential polarization visibilities RQ and RU of an object are the ratios of its visibilities corresponding to orthogonal polarizations, the interferometric analogs to Stokes Q and U intensity images. The measurement of differential polarization visibilitites can be used for constraining inner parts of circumstellar envelopes of young or evolved stars at the diffraction limited resolution of the feeding telescope. We demonstrate the estimation of both amplitude and phase of RQ and RU from data obtained using SCExAO VAMPIRES through the full pupil of the 8-m Subaru telescope using the differential speckle polarimetry technique. The correction for biases arising due to instrumental polarization effects is discussed. The accuracy of RQ and RU measurement with VAMPIRES is limited by imperfect knowledge of instrumental polarization and amounts to 5  ×  10  −  3.