Abstract: An electro-optical system is disclosed for measuring rotational angle. The system includes a radiation source and reference linear polarizer in combination with a plurality of linear target polarizers. Photosensors are arranged to receive modulated light separately from an adjacent pair of target polarizers. Pulsed electrical output signals representative of the modulated light received by the photosensors are generated. Means are provided for comparing output signals from the sensors and generating a signal representative of rotational angle between the reference and target. The angle of rotation between the reference linear polarizer and the target linear polarizers is thereby converted to a representative signal which may be used to drive a servo motor or other device operatively connected to a rotatable element directly or indirectly. The reference polarizer may be held in a fixed position or it may be mounted on an independently rotatable element.