Los puntos clave no están disponibles para este artículo en este momento.
A new servo system has been developed in which the connecting link between the primary and secondary shafts is polarized light whose plane of polarization rotates with the primary shaft. This makes possible the accurate following of the rotation of the primary shaft without any load being imposed on it. This servo system has been applied successfully in several electro-mechanical calculating machines.
T. M. Berry (Sat,) studied this question.