LASER DOPPLER SPEEDOMETER

PURPOSE:To make it possible to measure a particle size and a particle concn. simultaneously with a particle speed, by imparting a particle size analytical analysis to a laser Doppler speedometer. CONSTITUTION:A burst signal is analysed in state separated into a high frequency component and a low frequency component. That is, the high frequency component is analyzed by a frequency analyser 10 while the low frequency component is analyzed by a pulse crest analyser 13 and the synchronism of both signals is discriminated by a signal analyser 14 and, if both signals are synchronous, it is discriminated that both signals are ones generated from one particle which passed a measuring point and both signals are recorded by buffer memory 11. This operation is repeated many times and statistical processing is performed by using a counter 12 to measure a particle size simultaneously with a particle speed. The frequency of a Doppler signal being the flow speed component in the burst signal and the pulse crest value of a pedestal signal being a particle size component are recorded as a pair by the buffer memory 11. The frequency fD of the Doppler signal is converted to the speed V of the particle from this buffer memory 11.