A system to spatially modulate light includes an optical reflector to reflect the light. The optical reflector has an actuator that includes a stator and a rotor. The system further includes a controller in communication with the optical reflector. The controller is to drive the optical reflector by applying an excitation voltage between the rotor and the stator. Further, the controller is to apply a baseline voltage between the rotor and the stator, and to detect, during a voltage-off period of the excitation voltage, an induced current induced by the rotor moving relative to the stator. Furthermore, the controller is to determine a current attribute of the induced current and to determine a movement attribute of the optical reflector based on the current attribute.