Research On Laser Doppler Velocimeter

In order to meet the need of laser doppler velocimeter inland,a dual-beam direction recognizable LDV is designed in this papper.We design the index path of tachometer in this papper,use phase locked loop to increase measuring range of frequency.The theory of Doppler is analyzed and experimental research is done on it in this work.A beam come out of semiconductor laser which have a 905nm wavelength, 1.2mrad divergence angle and the maxima radiation density is 11w/cm,then It is divided by spectroscope.one of the beam'frequence has shifted 40MHz after frequency shifter then it couple and focus onto the mobile with the other beam.We receive the signal of reflected light,then take use of optical heterodyne method to measure Doppler frequency shift of the mobile,calculate velocity by the relation between Doppler shift and velocity. measuring range 0—150m/s ,accuracy 1%, distinguishability 10μm.