Abstract
The linear polarimetric measurements are given by the measurements of the Stokes parameters Q and U. In the existing polarimeter, the Q and U parameters are not measured at one exposure. It leads to uncertainties of the resultant accuracy because of the tracking error of the telescope and changes in atmospheric conditions. Therefore, to enhance the polarimetric accuracy and observational efficiency, we are constructing an imaging polarimeter which can measure the Stokes parameter Q and U, simultaneously. The polarimeter employs an unpolarized beam splitter and two Wollaston prisms, allowing the simultaneous acquisition of the four polarized images without moving parts.
The test-observations of the polarimeter have been made in January 2006, mounted on the Cassegrain focus of the 60cm telescope at Nishiharima Astronomical Observatory, Hyogo, Japan. By using the observational value of the unpolrized standard stars, we have estimated the instrumental polarization of 0.81% for the polarimeter and telescope system. The accuracy of the measurements is +/- 0.12%. Moreover the calibrated polarization of the polarized standard stars coincides with the value in literature within 0.2%.
