抄録
Two methods are reported in this paper for measuring velocity gradients, namely, by means of the laser Doppler effect and the spatial filtering effect. The velocity gradient is determined from measurements of the velocity difference at two probing points of the object. The properties of output beat signals are theoretically studied from the spectral broadening. A preliminary experiment is performed by using rotating disks. In addition, both the laser Doppler method and the spatial filter method are compared in theory and experiment. The results show the feasibility of both methods for measuring velocity gradients.
