ABSTRACT
A laser Doppler velocimeter (LDV) has been a standard apparatus for measur the velocity of a uid ow, gas ow, or rigid object in various research elds industries since the introduction of the concept in 1964 [1]. A differential LDV the advantages of its noninvasive nature, small measurement volume giving ex lent spatial resolution, and linear response. In many applications concerning vel ity measurements, velocity distribution of the object often needs to be measur For this purpose, various mechanical scanning techniques in differential LDVs h been proposed [2-7]. In these scanning LDVs, a moving mechanism is used in tra mitting optics to scan the measurement point, for example, a movable lens [2
6.1 Introduction .................................................................................................. 6.2 Differential LDV........................................................................................... 6.3 Nonmechanical Scanning LDV .................................................................... 6.4 Directional Discrimination for Nonmechanical Scanning LDV ..................
