Abstract：Real time velocity tracing based on self-mixing speckle in a Q-type fiber resonator was proposed.The measurement system of self-mixing speckle was mainly built up by an erbium-doped fiber(EDF),a partially reflecting optical fiber grating(FBG),and a wavelength division multiplexing(WDM).Self-mixing speckle was produced by part of light backscattered from a moving object mixing with the original one in the Q cavity.The expression of the laser output power was also deduced theoretically.A round rotating aluminum plate was set as the measured target,whose velocity was controlled by a stepping motor.The LabVIEW program was developed to real-time process the speckle signals on waveform acquisition,noise reducing and date calculations.A linear relationship between the energy density of speckle signals and the velocity of the moving object was obtained.Based on the relationship,the line velocity at the side of the round aluminum plate was detected in real time in the range of velocity 175~456 mm/s.Our study showed that the all-fiber system for velocity measurement based on self-mixing speckle in a Q-ring cavity could be used for the measurement of a dynamic rough surface instantaneously.
2012, Vol. 36 
