SEDL / STP / STP990-EB / STP26042S

Parameters Controlling Counting Efficiency for Optical Liquid-Borne Particle Counters

Lieberman, A
Technical Specialist, Particle Measuring Systems, Inc., Fremont, CA

Pages: 11    Published: Jan 1989

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Abstract

Present-day optical liquid-borne particle counters (OPCs) present data in digital format, frequently accepted as absolute by many users. However, counting efficiency of these devices is affected by instrument design, performance and operation. This discussion summarizes some of the pertinent parameters affecting OPC accuracy, explains effects on data and indicates means of maximizing OPC efficiency. Operation of OPCs using light extinction or scattering is described, including discussion of the pertinent optical parameters. Effects on OPC response are summarized, considering the relationships between the optical properties of the calibration material and typical contaminants with those of the liquid. It is shown that as OPC response varies with differential refractive index, then particle counts for polydisperse materials will also change.