Abstract: The principle to produce the motional coordinate in time-grating displacement sensor is analyzed. In order to sim-plify the structure of the time-grating sensor and make its manufacture easily, its fluctuation function is analyzed and the relation and distinction between electric travelling wave and magnetic travelling wave are discussed. Then a new method to produce traveling wave is proposed based on these discussions. The method is employed with its corresponding mechanical structure to form a new type time-grating sensor. Experimental results show that the sensor can generate correct signal and the method is feasible. Thus the traditional electrical machinery method can be replaced by a new method to produce the mo-tional magnetic field. This new method can simplify the manu-facture process greatly.

Key words: Fluctuation function, Standing wave, Time-grating, Travelling wave