Particle analysis system and method
First Claim
1. A method of particle analysis, comprising:
- (a) exposing a number of particles in a particle suspension to an incident light with a time-varying intensity, the particles being sufficiently close to one another to multiply scatter light;
(b) detecting multiply scattered light from the particles in response to the incident light to provide a first value corresponding to a measurement of an optical property of the particles, the first value being determined as a function of time-dependent propagation of the multiply scattered light through the particle suspension;
(c) establishing a second value corresponding to an estimation of at least one of volume fraction and size distribution of the particles;
(d) calculating a third value as a function of the second value, the third value corresponding to a prediction of the optical property based on the estimation;
(e) comparing the first and third values to establish an error;
(f) changing the second value as a function of the error; and
(g) repeating said calculating, comparing, and changing until the error reaches a desired minimum.
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Accused Products
Abstract
A system and method are disclosed for the self-calibrating, on-line determination of size distribution and volume fraction of a number of particles dispersed in a medium by detecting multiply scattered light from the particles. The multiply scattered light is re-emitted in response to exposure to a light source configured to provide light of time varying intensity at selected wavelengths. The determination includes calculating the isotropic scattering coefficient for the particles at each of a number of wavelengths from the multiply scattered light as a function of an intensity modulation phase shift, and iteratively estimating the size distribution and volume fraction as a function of the isotropic scattering coefficient for each of the wavelengths. An estimation approach based on an expected form of the distribution and the mass of the particles is also disclosed.
123 Citations
35 Claims
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1. A method of particle analysis, comprising:
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(a) exposing a number of particles in a particle suspension to an incident light with a time-varying intensity, the particles being sufficiently close to one another to multiply scatter light; (b) detecting multiply scattered light from the particles in response to the incident light to provide a first value corresponding to a measurement of an optical property of the particles, the first value being determined as a function of time-dependent propagation of the multiply scattered light through the particle suspension; (c) establishing a second value corresponding to an estimation of at least one of volume fraction and size distribution of the particles; (d) calculating a third value as a function of the second value, the third value corresponding to a prediction of the optical property based on the estimation; (e) comparing the first and third values to establish an error; (f) changing the second value as a function of the error; and (g) repeating said calculating, comparing, and changing until the error reaches a desired minimum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for analyzing a number of particles suspended in a medium in sufficient concentration to multiply scatter light, comprising:
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(a) a light source configured to expose the medium to a number of different wavelengths of light each being intensity-modulated at a predetermined frequency; (b) a first sensor spaced apart from the source, the sensor being configured to provide a first detection signal corresponding to multiply scattered light from the particles at the different wavelengths in response to exposure to the source; (c) a processor responsive to the first detection signal to generate;
(i) an observed signal for each of the wavelengths as a function of time, the observed signal being representative of an optical property of the particles in the medium, the observed signal being determined from at least one of a phase shift or a modulation amplitude of the multiply scattered light relative to the predetermined frequency for each of the wavelengths, and (ii) an output signal corresponding to a size distribution or volume fraction of the particles as a function of the observed signal or each of the wavelengths; and(d) an output device responsive to the output signal to provide an output corresponding to the size distribution or volume fraction. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A system for analyzing a number of particles suspended in a medium in sufficient concentration to multiply scatter light, comprising:
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(a) a light source configured to expose the medium to a number of different wavelengths of light; (b) a sensor spaced apart from the source, the sensor being configured to provide a emission signal corresponding to multiply scattered light from the particles at the different wavelengths in response to exposure to the source; (c) a processor responsive to the first emission signal, the processor including a means for generating an output signal representative of a size distribution or volume fraction of the particles as a function of an isotropic scattering coefficient, the processor being configured to determine a value representative of the isotropic scattering coefficient from the emission signal; and (d) an output device responsive to the output signal to provide an output corresponding to the size distribution or volume fraction. - View Dependent Claims (17, 18, 19, 20)
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21. A method of particle analysis, comprising:
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(a) exposing a number of particles to a number of wavelengths of light of time-varying intensity; (b) detecting multiply scattered light from the particles in response to said exposing to determine a first number of values from a mathematical relationship modeling time-dependent propagation of the multiply scattered light through the particles, the first values each being representative of an optical property of the particles and each corresponding to a different one of the wavelengths, and (c) determining a second value representative of a size distribution of the particles as a function of the first values. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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29. A method of particle analysis, comprising:
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(a) providing a number of particles sufficiently concentrated in a medium to multiply scatter light; (b) sensing multiply scattered light from the particles to determine a number of observed values corresponding to an optical property of the particles; and (c) generating an output representative of the volume fraction of the particles by comparing each of the observed values to a corresponding one of a number of calculated values, the calculated values being representative of the optical property and being determined as a function of an estimate corresponding to the volume fraction. - View Dependent Claims (30, 31, 32, 33, 34, 35)
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Specification