Abstract: In order to realize the detection of small flow in laser self-mixing speckle interference，a self-mixing
speckle interference detection method based on laser is proposed． The method relies on the self-mixing speckle
interference signal obtained by the detection，the average frequency of the fluid is obtained by spectrum analysis
of the signal，and the average frequency is utilized． The line of fit with the flow rate further obtains the
relationship between the flow rate and the average frequency to accurately solve the small flow of the fluid．
Theoretical analysis and experiments show that the method can measure small flow easily and efficiently，and the
relative error of measurement is less than 1． 13%．

Key words: laser self-mixing, speckle interference, average frequency, small flow