Ginkgo biloba extract

A reference beam type optical laser Doppler velocimeter for emitting two or more probe beams to an object to be measured at a predetermined angle to multi-dimensionally measure a velocity and/or a displacement vector of the object due to Doppler shifts of beams reflected by the object. This velocimeter includes a frequency shifting means for dividing a laser beam from a single light source into two or more beams, and shifting optical frequencies of the beams each by a predetermined shift amount, a photodetecting means for receiving the reflected and reference beams to obtain a detection current, and a bandpass filter for causing the detection current to pass therethrough to obtain a required signal.