PRECISE MEASUREMENT OF THE EXTINCTION RATIO OF A POLARIZATION ANALYZER

We determined the extinction ratio of a polarization analyser on the b asis of Malus' law by relating the transmitted light intensity to the analyser azimuth measured at only a small range of analyser azimuth an gles around the minimum position, thus avoiding the requirement for an optical detector with a high dynamic range. To adjust the orientation of the analyser azimuth we manufactured a precise rotation stage whic h had an angular resolution of less than 1 mu rad. The minimum value o f the extinction ratio was 2.9 x 10(-10), obtained for a polarization analyser of the Glan-Taylor type. To calibrate the apparatus we measur ed the Faraday rotation of a glass plate placed in a magnetic field in the optical path.