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The Pulse Displacement Technique — a single particle counter with a size range larger than 1000: 1
Author(s) -
Hess Cecil F.,
Wood Craig P.
Publication year - 1994
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.19940110114
Subject(s) - range (aeronautics) , particle counter , particle (ecology) , materials science , particle size , pulse (music) , displacement (psychology) , optics , physics , chemistry , aerosol , geology , composite material , detector , psychology , oceanography , psychotherapist , meteorology
This paper describes the pulse displacement technique(PDT) to simultaneously measure particle size and velocity in applications characterized by a large size range and high particle concentration. PDT is based on the detection of scattered refraction and reflection pulses which sweep past a detector at different times as a particle traverses a narrow probe volume. Basic analytical relationships are presented which allow the calculation of the spatial and temporal widths and separations of the reflection and refraction pulse as a function of particle diameter and velocity. Two implementations of PDT are discussed using one or two receivers with two laser sheets having the same or different wavelengths. This paper also discusses several methods to measure particle velocity with PDT, discusses the limitations associated with signal broadening in practical systems, and briefly presents experimental results which show that the temporal separation between the refraction and reflection and reflection pulse maxima is independent of collecting lens f‐number from f/3 to f/20 for particle sizes ranging from 250 to 2000 μm.