Precise measurement of the extinction ratio of a polarization analyser

We determined the extinction ratio of a polarization analyser on the basis of Malus' law by relating the transmitted light intensity to the analyser azimuth measured at only a small range of analyser azimuth angles 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 which had an angular resolution of less than rad. The minimum value of the extinction ratio was , obtained for a polarization analyser of the Glan - Taylor type. To calibrate the apparatus we measured the Faraday rotation of a glass plate placed in a magnetic field in the optical path.