In order to overcome the inherent weakness in the mechanical scanning laser Doppler anemometry (LDA) system, the laser beam scanning was realized by means of the deflection of the diffracted laser beam occuring in the acousto-optic interaction to construct an acousto-optic scanning LDA (AOS-LDA). Because there are no any movable or rotational optical elements in the AOS-LDA, the limitations induced by mechanical inertia was then eliminated. The instantaneous regurgitant velocity profiles obtained from the mitral heart valve prothesis (MHVP) test installed in a mock circulatory loop can be used to evaluate the regurgitation characteristic of the MHVP in vitro.