US 4,781,460 AGranted

System for measuring the size distribution of particles dispersed in a fluid

AssigneeCoulter Electronics of New England, Inc.

InventorSteven E. Bott

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Abstract

An apparatus and method which provides a measure of the size distribution of particles dispersed in a fluid based upon an optimum combination of CLS measurements and DLS measurements. The measurement is characterized by relatively high resolution particle sizing. DLS data representative of the autocorrelation function, or power spectrum, of the detected intensity of scattered light for m measurement conditions of a sample, is optimally combined with CLS data representative of the average total detected intensity of scattered light for n measurement conditions, to provide an angle-independent, high resolution size distribution v(r), where m.gtoreq.1, n.gtoreq.0, m+n.gtoreq.2, and at least two of the measurement conditions are different. The size distribution may be expressed in terms of the continuous function v(r) or the histogram v, and may represent distributions weighted by mass, volume, number, surface area, or other measures.

Claims44

Dependent claims

A system for measuring the size distribution v(r) of particles dispersed in a fluid sample, where r is representative of particle size, comprising:

A. illumination means for illuminating said sample with a light beam directed along an input axis,
B. detector means for detecting the intensity of light scattered from said light beam by said sample for m measurements made under an associated one of a set of m measurement conditions, and for n measurements made under an associated one of a set of n measurement conditions, where m is an integer equal to or greater than one, and n is an integer equal to or greater than zero, and the sum of m and n is equal to or greater than two, and at least two of said m+n measurement conditions are different, said detector means further including:
i. means for generating m intensity signals, each of said intensity signals being representative of the detected intensity of said scattered light as a function of time under a corresponding one of the measurement conditions of said set of m measurement conditions,
ii. means for generating n average signals, each of said n average signals being representative of the average intensity of said scattered light detected under a corresponding one of the measurement conditions of said set of n measurement conditions,
C. autocorrelation means for generating m correlation signals, each of said correlation signals being representative of the autocorrelation function of a corresponding one of said intensity signals and being equal to an associated transformation of said distribution v(r),
D. size processing means responsive to said correlation signals and said average signals, including:
i. preprocessor means responsive to said m correlation signals for generating a composite correlation signal,
ii. means for generating a composite scattered light signal from said composite correlation signal and said n average signals
iii. means for determining a composite transformation operator J.sup.-1 related to said associated transformations and said n average signals,
iv. means for transforming said composite scattered light signal in accordance with said determined composite transformation operator J.sup.-1 to generate a size distribution signal representative of said distribution v(r), and
E. means for controlling said m+n measurement conditions whereby said intensity signals are mutually independent and said average signals are mutually independent.

8 more elements

A method for measuring the size distribution v(r) of particles dispersed in a fluid sample, where r is representative of particle size, comprising the steps of:

A. illuminating said sample with a light beam directed along an input axis,
B. detecting the intensity of light scattered from said light beam by said sample for m measurements made under an associated one of a set of m measurement conditions, and for n measurements made under an associated one of a set of n measurement conditions, where m is an integer equal to or greater than one, and n is an integer equal to or greater than zero, and the sum of m and n is equal to or greater than two, and at least two of said m+n measurement conditions are different, including the substeps of:
i. generating m intensity signals, each of said intensity signals being representative of the detected intensity of said scattered light as a function of time under a corresponding one of the measurement conditions of said set of m measurement conditions,
ii. generating n average signals, each of said n average signals being representative of the average intensity of said scattered light detected under a corresponding one of the measurement conditions of said set of n measurement conditions,
C. generating m correlation signals, each of said correlation signals being representative of the autocorrelation function of a corresponding one of said intensity signals and being equal to an associated transformation of said distribution v(r),
D. in response to said correlation signals and said average signals, including the substeps of:
i. preprocessing said m correlation signals for generating a composite correlation signal,
ii. generating a composite scattered light signal from said composite correlation signal and said n average signals
iii. determining a composite transformation operator J.sup.-1 related to said associated transformations and said n average signals,
iv. transforming said composite scattered light signal in accordance with said determined composite transformation operator J.sup.-1 to generate a size distribution signal representative of said distribution v(r), and
E. controlling said m+n measurement conditions whereby said intensity signals are mutually independent and said average signals are mutually independent.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/068,139Filed 29 Jun 1987 · continuation in part
Priority: 8 Jan 1986
Granted: 1 Nov 1988
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01N 15/0205
Investigating particle size or size distribution: by optical means
G01J 3/4412
Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry: scattering spectrometry
G01N 2015/0222
Investigating a scatter or diffraction pattern: from dynamic light scattering, e.g. photon correlation spectroscopy
G01N
Investigating or analysing materials by determining their chemical or physical properties