CHARACTERISTICS OF A MINIATURIZED PROBE EMPLOYING THE PULSE DISPLACEMENT TECHNIQUE

This paper describes a miniaturized particle sizing velocimeter develo ped and built by MetroLaser to measure the spatial and temporal distri butions of particle size and velocity. The instrument is the first of its kind to utilize the pulse displacement technique (PDT) to measure particle size. PDT is based on the detection of scattered refraction a nd reflection pulses which sweep past a detector at different times as a particle traverses a narrow laser sheet. In conjunction with Mie sc attering and a time-of-fight velocity measuring technique, the instrum ent provides detailed distributions of particle size from 2 mu m to 60 00 mu m in two optical configurations, and particle velocity from 0.5 m/s to 150 m/s. This paper summarizes the theoretical foundation of PD T which allows the calculation of particle diameter from Various optic al parameters such as refractive index and collection angle. An overvi ew of the instrument is presented, followed by a brief description of the miniaturized optical probe. The processing of data is described an d lastly, the results of experimental studies are presented which veri fy the accuracy and versatility of the instrument.