A study on torque measurement based on laser Doppler technology

An amended method of torque measurement based on laser Doppler technology and the principle of optical heterodyne is described. The principle is analyzed, the mathematical model of the optical configuration developed, and the feasibility tested. With the laser beams at four points of twain sections, the relative rotation velocity of twain sections is measured. By integrating the relative rotation velocity, the relative rotation angle is acquired, therefore the torque measurement is realized. The relative rotation velocity of twain sections is measured directly with one photodetector and one demodulator. The accuracy of torque measurement is improved by avoiding the error caused by the different propagation delay of demodulators.