Pendulum sensor for location of vertical by using polarization measurements

We consider a fast contactless sensor for information about the position of a pendulum relative to a platform; the sensor is based on the use of polarization modulation of a light beam. We investigate problems on reducing the moment of force due to friction in the axial system of the pendulum. Translated from Izmeritel’naya Tekhnika, No. 1, pp. 18–21, January, 1998.