Fiber-optic Doppler velocimeter that incorporates active optical feedback from a diode laser.

A fiber-optic Doppler velocimeter that incorporates the effect of self-mixing in a diode laser is described. A theoretical model, based on self-mixing interference theory, is presented, and a simple experimental arrangement is constructed. The results of the experimental research are found to be in good agreement with the theoretical analysis. A Doppler velocity of as much as 3 m/s was measured directly, and a good linear relationship between the Doppler velocity and the Doppler-shifted frequency was obtained, which can be used to determine the speed of a moving object.