Abstract: A rate sensor is disclosed comprising a motor driven elastic disk rotor, a light source for illuminating the surface of the disk rotor, a plurality of light detectors mounted on the x or y or both axes of the rate sensor, and a signal processor including a differential amplifier for producing electrical signals representative of the quantity of light detected by the light detectors, the light reflected by the elastic disk is deflected by the disk bending responsive to torque or couple forces applied to the rate sensor and detected by the light detectors to produce electrical signals representative thereof, the electrical signals are coupled to a difference amplifier and dc signals representative of the direction and angular rate of movement of the rate sensor are produced.