US3873206A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for determining a specific characteristic of fluid suspended particles
Assignee: Leeds and Northrup Co
•
Filing: 1973-10-03
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Granted: 1975-03-25
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Expires: 1993-10-03
Abstract
Abstract A method for determining a specific characteristic of fluid suspended particles such as determining the total volume of particulate, as in stack gases. A laser beam is passed through the stack gases to produce diffraction patterns which are spatially filtered so that the total diffracted light flux passing through the filter is proportional to the total volume and hence the mass of the particles. A central opaque region is used on the filter to intercept the incident laser beam. The portion of diffracted light which is intercepted by that opaque region is compensated for by a region of enhanced transmission next to the center to restore response relating to the large particles. The spatial filter transmits a fraction of the diffracted light proportional to the reciprocal of the diffraction angle so that the total flux will be proportional to the cube of the diameter of the particulate and hence the particulate volume. When a long path is involved the particle information which is lost is compensated for by an enhanced transmission of the diffracted light from nearby small particles. Thus, in an outer region of the filter the transmission factor is held constant to provide the necessary compensation for the lost light flux.
Inventors
- 👤 William Leslie Wilcock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:18
CPC Classifications
G; G01; G01N; G01N15/00; G01N15/02; G01N15/0205; G01N15/0211; G01N21/00; G01N21/17; G01N21/47; G01N2021/4704; G01N2021/4711; G01N2021/4716
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
132 words
A method for measuring the specific characteristic of fluid suspended particles comprising the steps of: passing a light beam through a sample of said fluid, filtering with a spatial filter the light diffracted from said beam by the suspended particles in said sample, said filter having a transmission factor which varies as a function of the distance from the axis of said beam in a manner such that the magnitude of the total light flux transmitted due to each individual particle has a functional relationship to the dimensions of the particle which makes the total light flux transmitted due to all of the suspended particles proportioNal to the magnitude of said characteristic, and detecting the magnitude of the total light flux transmitted by said filter as a measure of said specific characteristic.
Claim 2
Independent Claim
132 words
A method for measuring the specific characteristic of fluid suspended particles comprising the steps of: passing a light beam through a sample of said fluid, filtering with a spatial filter the light diffracted from said beam by the suspended particles in said sample, said filter having a transmission factor which varies as a function of the distance from the axis of said beam in a manner such that the magnitude of the total light flux transmitted due to each individual particle has a functional relationship to the dimensions of the particle which makes the total light flux transmitted due to all of the suspended particles proportioNal to the magnitude of said characteristic, and detecting the magnitude of the total light flux transmitted by said filter as a measure of said specific characteristic.
Claim 3
Dependent Claim
35 words
The method of claim 1 in which the specific characteristic is the volume of the particles and the transmission factor of the filter varies inversely with the radial distance from the axis of the beam.
Claim 4
Dependent Claim
43 words
The method of claim 1 in which the particles are of the same density and the specific characteristic is the mass of the particles with the transmission factor of the filter varying inversely with the radial distance from the axis of the beam.
Claim 5
Dependent Claim
14 words
The method of claim 2 in which the light beam is a collimated beam.
Claim 6
Dependent Claim
45 words
The method of claim 4 which includes the step of: collecting with an optical focusing element the diffracted light from the suspended particles in said light beam and wherein said filtering involves the filtering of a portion of the collected light by said spatial filter.
Claim 7
Independent Claim
136 words
A method for measuring the specific characteristic of fluid suspended particles comprising the steps of: passing a light beam through a sample of said fluid, filtering with a spatial filter in the Fraunhofer plane, the light diffracted from said beam by the suspended particles in said sample, said filter having a transmission factor which varies as a function of the distance from the axis of said beam in a manner such that the magnitude of the total light flux transmitted due to each individual particle has a functional relationship to the dimensions of the particle which makes the total light flux transmitted due to all of the suspended particles proportional to the magnitude of said characteristic, and detecting the magnitude of the total light flux transmitted by said filter as a measure of said specific characteristic.
Claim 8
Independent Claim
136 words
A method for measuring the specific characteristic of fluid suspended particles comprising the steps of: passing a light beam through a sample of said fluid, filtering with a spatial filter in the Fraunhofer plane, the light diffracted from said beam by the suspended particles in said sample, said filter having a transmission factor which varies as a function of the distance from the axis of said beam in a manner such that the magnitude of the total light flux transmitted due to each individual particle has a functional relationship to the dimensions of the particle which makes the total light flux transmitted due to all of the suspended particles proportional to the magnitude of said characteristic, and detecting the magnitude of the total light flux transmitted by said filter as a measure of said specific characteristic.
Claim 9
Dependent Claim
45 words
A method as set forth in claim 6 which also includes the step of collecting with an optical focusing element the light diffracted from said beam by the suspended particles in said sample and in which the filtering is a filtering of the collected light.
Claim 10
Dependent Claim
133 words
Apparatus for measuring a specific characteristic of fluid suspended particles comprising: means for passing a light beam through a sample of said fluid, a spatial filter for filtering the light diffracted from said beam by the suspended particles in said sample, said filter having a transmission factor which varies as a function of the distance from the axis of said beam in a manner such that the magnitude of the total light flux transmitted due to each individual particle has a functional relationship to the dimensions of the particle which makes the total light flux transmitted due to all of the suspended particles proportional to the magnitude of said characteristic, and means for detecting the magnitude of the total light flux transmitted by said spatial filter as a measure of said specific characteristic.
Claim 11
Dependent Claim
133 words
Apparatus for measuring a specific characteristic of fluid suspended particles comprising: means for passing a light beam through a sample of said fluid, a spatial filter for filtering the light diffracted from said beam by the suspended particles in said sample, said filter having a transmission factor which varies as a function of the distance from the axis of said beam in a manner such that the magnitude of the total light flux transmitted due to each individual particle has a functional relationship to the dimensions of the particle which makes the total light flux transmitted due to all of the suspended particles proportional to the magnitude of said characteristic, and means for detecting the magnitude of the total light flux transmitted by said spatial filter as a measure of said specific characteristic.
Claim 12
Dependent Claim
37 words
Apparatus as set forth in claim 8 in which the specific characteristic is the volume of the particles and the transmission factor of the filter varies inversely with the radial distance from the axis of the beam.
Claim 13
Dependent Claim
23 words
Apparatus as set forth in claim 9 in which the light beam passed through the sample of said fluid is a collimated beam.
Claim 14
Dependent Claim
37 words
Apparatus as set forth in claim 10 which also includes an optical focusing element for collecting the light diffracted from said beam by the suspended particles in said beam and said spatial filter filters the collected light.
Claim 15
Dependent Claim
155 words
Apparatus for measuring a specific characteristic of fluid suspended particles comprising: means for passing a collimated light beam through a sample of said fluid, means for collecting with an optical focusing element the forward scattered light from the suspended particles in said light beam, a spatial filter in the Fraunhofer plane of said optical focusing element, said filter having a transmission factor which varies as a function of the radial distance form the axis of said beam in a mAnner such that the magnitude of the total light flux transmitted due to each individual particle has a functional relationship to the diameter of the particle with that functional relationship being such that the total light flux transmitted due to all of the suspended particles is proportional to the magnitude of said characteristic, and means for detecting the magnitude of the total light flux transmitted by said spatial filter as a measure of said specific characteristic.
Claim 16
Dependent Claim
155 words
Apparatus for measuring a specific characteristic of fluid suspended particles comprising: means for passing a collimated light beam through a sample of said fluid, means for collecting with an optical focusing element the forward scattered light from the suspended particles in said light beam, a spatial filter in the Fraunhofer plane of said optical focusing element, said filter having a transmission factor which varies as a function of the radial distance form the axis of said beam in a mAnner such that the magnitude of the total light flux transmitted due to each individual particle has a functional relationship to the diameter of the particle with that functional relationship being such that the total light flux transmitted due to all of the suspended particles is proportional to the magnitude of said characteristic, and means for detecting the magnitude of the total light flux transmitted by said spatial filter as a measure of said specific characteristic.
Claim 17
Dependent Claim
41 words
The apparatus as set forth in claim 12 in which the specific characteristic is the volume of the particles and in which the transmission factor of the spatial filter varies inversely with the radial distance from the axis of the beam.
Claim 18
Independent Claim
172 words
A method for measuring the total volume of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light from the particles in said certain size range along the path, blanking out the incident light from said beam, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected within the radial distance from the axis of the beam representing the angle of scatter of the smallest particles of said size range along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, and detecting the magnitude of the total light flux transmitted as a measure of the total volume of the particles in said size range along the full length of said path.
Claim 19
Independent Claim
172 words
A method for measuring the total volume of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light from the particles in said certain size range along the path, blanking out the incident light from said beam, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected within the radial distance from the axis of the beam representing the angle of scatter of the smallest particles of said size range along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, and detecting the magnitude of the total light flux transmitted as a measure of the total volume of the particles in said size range along the full length of said path.
Claim 20
Independent Claim
283 words
A method for measuring the total volume of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light from the particles in said certain size range along the path, blanking out the light flux collected within a radial distance from the axis of the beam representing a small angle of scatter and forming a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outer region within the radial distance from the axis of the beam representing the angle of scatter of the smallest particles of said size range along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, filtering with said spatial filter the light collected in a region established between said outer region and said central region so as to transmit a fraction of the light collected in that region which is of magnitude exceeding that which would be transmitted in accordance with an inverse relationship to the radial distance from the axis of said beam by an amount to compensate for the diffracted light blanked out by the central region, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total volume of the particles in said size range along the full length of said path.
Claim 21
Independent Claim
283 words
A method for measuring the total volume of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light from the particles in said certain size range along the path, blanking out the light flux collected within a radial distance from the axis of the beam representing a small angle of scatter and forming a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outer region within the radial distance from the axis of the beam representing the angle of scatter of the smallest particles of said size range along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, filtering with said spatial filter the light collected in a region established between said outer region and said central region so as to transmit a fraction of the light collected in that region which is of magnitude exceeding that which would be transmitted in accordance with an inverse relationship to the radial distance from the axis of said beam by an amount to compensate for the diffracted light blanked out by the central region, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total volume of the particles in said size range along the full length of said path.
Claim 22
Independent Claim
285 words
A method for measuring the total volume of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light in said certain size range for particles in a part only of the path and collecting less than all of the forward scattered light from the smaller particles in said size range in the remainder of the path, blanking out a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outermost region from the particles with angles of scatter exceeding the maximum angle of scatter of diffracted light for particles in said size range collected over the full length of the path so that the fraction of the collected light transmitted is constant over the radial distance from the axis of said beam represented by those angles of scatter, filtering with said spatial filter the light collected in an outer region within the radial distance from the axis of said beam represented by the angle of scatter of the smallest particles of said size range collected along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total volume of the particles in said size range along the full length of said path.
Claim 23
Independent Claim
285 words
A method for measuring the total volume of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light in said certain size range for particles in a part only of the path and collecting less than all of the forward scattered light from the smaller particles in said size range in the remainder of the path, blanking out a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outermost region from the particles with angles of scatter exceeding the maximum angle of scatter of diffracted light for particles in said size range collected over the full length of the path so that the fraction of the collected light transmitted is constant over the radial distance from the axis of said beam represented by those angles of scatter, filtering with said spatial filter the light collected in an outer region within the radial distance from the axis of said beam represented by the angle of scatter of the smallest particles of said size range collected along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total volume of the particles in said size range along the full length of said path.
Claim 24
Independent Claim
381 words
A method for measuring the total volume of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light in said certain size range for particles in a part only of the path and collecting less than all of the forward scattered light from the smaller particles in said size range in the remainder of the path, blanking out the light flux collected within a radial distance from the axis of the beam representing a small angle of scatter and forming a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outermost region from the particles with angles of scatter exceeding the maximum angle of scatter of diffracted light for particles in said size range collected over the full length of the path so that the fraction of the collected light transmitted is constant over the radial distance from the axis of said beam represented by those angles of scatter, filtering with said spatial filter the light collected in an outer region within the radial distance from the axis of said beam represented by the angle of scatter of the smallest particles of said size range collected along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, filtering with said spatial filter the light collected in a region established between said outer region and said central region so as to transmit a fraction of the light collected in that region which is of magnitude exceeding that which would be transmitted in accordance with an inverse relationship to the radial distance from the axis of said beam by an amount to compensate for the diffracted light blanked out by the central region, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total volume of the particles in said size range along the full length of said path.
Claim 25
Independent Claim
381 words
A method for measuring the total volume of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light in said certain size range for particles in a part only of the path and collecting less than all of the forward scattered light from the smaller particles in said size range in the remainder of the path, blanking out the light flux collected within a radial distance from the axis of the beam representing a small angle of scatter and forming a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outermost region from the particles with angles of scatter exceeding the maximum angle of scatter of diffracted light for particles in said size range collected over the full length of the path so that the fraction of the collected light transmitted is constant over the radial distance from the axis of said beam represented by those angles of scatter, filtering with said spatial filter the light collected in an outer region within the radial distance from the axis of said beam represented by the angle of scatter of the smallest particles of said size range collected along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, filtering with said spatial filter the light collected in a region established between said outer region and said central region so as to transmit a fraction of the light collected in that region which is of magnitude exceeding that which would be transmitted in accordance with an inverse relationship to the radial distance from the axis of said beam by an amount to compensate for the diffracted light blanked out by the central region, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total volume of the particles in said size range along the full length of said path.
Claim 26
Independent Claim
385 words
A method for measuring the total mass of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles of the same density in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light in said certain size range for particles in a part only of the path and collecting less than all of the forward scattered light from the smaller particles in said size range in the remainder of the path, blanking out the light flux collected within a radial distance from the axis of the beam representing a Small angle of scatter and forming a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outermost region from the particles with angles of scatter exceeding the maximum angle of scatter of diffracted light for particles in said size range collected over the full length of the path so that the fraction of the collected light transmitted is constant over the radial distance from the axis of said beam represented by those angles of scatter, filtering with said spatial filter the light collected in an outer region within the radial distance from the axis of said beam represented by the angle of scatter of the smallest particles of said size range collected along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, filtering with said spatial filter the light collected in a region established between said outer region and said central region so as to transmit a fraction of the light collected in that region which is of magnitude exceeding that which would be transmitted in accordance with an inverse relationship to the radial distance from the axis of said beam by an amount to compensate for the diffracted light blanked out by the central region, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total mass of the particles in said size range along the full length of said path.
Claim 27
Independent Claim
385 words
A method for measuring the total mass of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles of the same density in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light in said certain size range for particles in a part only of the path and collecting less than all of the forward scattered light from the smaller particles in said size range in the remainder of the path, blanking out the light flux collected within a radial distance from the axis of the beam representing a Small angle of scatter and forming a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outermost region from the particles with angles of scatter exceeding the maximum angle of scatter of diffracted light for particles in said size range collected over the full length of the path so that the fraction of the collected light transmitted is constant over the radial distance from the axis of said beam represented by those angles of scatter, filtering with said spatial filter the light collected in an outer region within the radial distance from the axis of said beam represented by the angle of scatter of the smallest particles of said size range collected along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, filtering with said spatial filter the light collected in a region established between said outer region and said central region so as to transmit a fraction of the light collected in that region which is of magnitude exceeding that which would be transmitted in accordance with an inverse relationship to the radial distance from the axis of said beam by an amount to compensate for the diffracted light blanked out by the central region, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total mass of the particles in said size range along the full length of said path.
Claim 28
Independent Claim
290 words
A method for measuring the total mass of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles of the same density in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light in said certain size range for particles in a part only of the path and collecting less than all of the forward scattered light from the smaller particles in said size range in the remainder of the path, blanking out of a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outermost region from the particles with angles of scatter exceeding the maximum angle of scatter of diffracted light for particles in said size range collected over the full length of the path so that the fraction of the collected light transmitted is constant over the radial distance from the axis of said beam represented by those angles of scatter, filtering with said spatial filter the light collected in an outer region within the radial distance from the axis of said beam represented by the angle of scatter of the smallest particles of said size range collected along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total mass of the particles in said size range along the full length of said path.
Claim 29
Independent Claim
290 words
A method for measuring the total mass of gas-entrained particles in a certain size range along a path through a sample volume having a uniform distribution of particles of the same density in that size range, comprising the steps of: passing a laser beam along said path, collecting with an optical focusing element all of the forward scattered light in said certain size range for particles in a part only of the path and collecting less than all of the forward scattered light from the smaller particles in said size range in the remainder of the path, blanking out of a central region so that the incident light from said beam is not transmitted, filtering with a spatial filter in the Fraunhofer plane of said focusing element the light collected in an outermost region from the particles with angles of scatter exceeding the maximum angle of scatter of diffracted light for particles in said size range collected over the full length of the path so that the fraction of the collected light transmitted is constant over the radial distance from the axis of said beam represented by those angles of scatter, filtering with said spatial filter the light collected in an outer region within the radial distance from the axis of said beam represented by the angle of scatter of the smallest particles of said size range collected along the full length of said path so that the fraction of the collected light transmitted varies inversely with the radial distance from the axis of said beam, and detecting the magnitude of the total light flux transmitted by said regions as a measure of the total mass of the particles in said size range along the full length of said path.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |