SYMPOSIA PAPER Published: 01 January 1990

Optical and Electronic Limitations of the Forward-Scattering Spectrometer Probe


An extensive evaluation of the optical and electronic measurement capabilities of the Particle Measurement Systems, Inc., forward-scattering spectrometer probe (FSSP) has led to a better characterization of this probe's measurement limitations. Measurements of droplet distributions are distorted as a result of mis-sizing and undercounting by the FSSP. These measurement errors have been traced to limitations imposed by the response time of the electronics, intensity inhomogeneities of the laser beam, and optical coincidence.

The optical and electronic characteristics of the FSSP have been mathematically modeled, and algorithms have been derived for the application of corrections that improve the accuracy of the measurements from these probes. These correction procedures adjust the measured concentrations for the effects of coincidence and deadtime losses and adjust the size distribution for undersizing caused by response time rolloff and laser beam inhomogeneities. This presentation summarizes the operational limitations of this instrument.

Author Information

Baumgardner, D
Cooper, WA
Dye, JE
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Developed by Committee: E29
Pages: 115–127
DOI: 10.1520/STP25416S
ISBN-EB: 978-0-8031-5141-3
ISBN-13: 978-0-8031-1459-3