In the traditional modulating technology, the objects are illuminated by the modulated laser beams. In general, this kind of illumination must past through some optics systems. The modulating illumination occurs at every optics component which the modulated laser beams pass through. These optics component must have some blemishes, which could produce the same frequency of the modulated laser beams and idle signals of stable phase. If these signals are in the field of view, they can produce background disturbance, so signal-to-noise becomes low. A new type of Doppler modulator which bases on Michelson-Morlery dynamic interference technology is introduced. Compared with the traditional modulating technology, the Doppler modulating technology is that the Doppler shift of the sample＇s moving leads to alternating variation of coherent field, which is used as modulating frequency. It can decrease effectively the background noise from modulating except for the target. Stabilization of the signal frequency presented by this type of Doppler modulator is about 1%, which could satisfy the need of reference signal of the lock-in amplifier.