Abstract: Apparatus intended for measuring the torque of rotating shafts for the purpose of calculating the shaft power without using sensors mounted or glued to the shaft. The long time accuracy is increased by using only one single optical electronic sensor in the pulse receiver. Alteration of sensor data due to temperature variations and aging do not affect the accuracy. The light is transmitted from the source/transmitter through optical fibre. The light beam is pulsed in two air gaps by coding discs/gearwheels mounted to the shaft at a convenient distance from each other (16 and 21). The light is transmitted by optical fibres (24a, 24b) from the source/transmitter (45) and via the optical U-shaped elements (39, 40) where the light beams are pulsed and added in the light collector (32). The time displacement between the vanes/teeth on the two discs/gearwheels is a measure on the shaft torque, enabling the shaft power to be calculated in the computer (50).