US3901602A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light scattering method and apparatus for the chemical characterization of particulate matter
Assignee: United States Department of Commerce
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Filing: 1974-05-13
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Granted: 1975-08-26
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Expires: 1994-05-13
Abstract
Abstract A light scattering method and apparatus for chemically identifying individual particles of matter or multiple particles of matter, such as are found in aerosols, without collecting and chemically analyzing the material. In the case of single particle analysis, plane-polarized light is impinged on the particle and the intensity of the light scattered into the plane of polarization over a specified angular range is measured. The intensity is related to the particle''s coefficient of absorption and its size. In multiple particle analysis, the intensity of the light scattered into a plane perpendicular to the plane of polarization is also measured to determine the total number of particles of matter. This information may be used to normalize the intensity measurement of the first scattered light beam. A smoke detector is presented as an apparatus embodying the multiple particle analysis technique whereby fire-produced aerosols may be detected without interference from non-fireproduced aerosols of similar density.
Inventors
- 👤 Jr Claude C Gravatt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:15
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/21; G01N21/47; G01N21/49; G01N21/53; G01N2021/4792
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
71 words
A method of determining the absorption coefficients of individual particles suspended in a fluid medium, comprising: impinging substantially plane-polarized light on an individual particle; and measuring the intensity of the light scattered by the particle into a divergent beam lying substantially in the plane of polarization of the impinging light and within an angular range from about 30* to about 90* with respect to the forward direction of the impinging light.
Claim 2
Independent Claim
71 words
A method of determining the absorption coefficients of individual particles suspended in a fluid medium, comprising: impinging substantially plane-polarized light on an individual particle; and measuring the intensity of the light scattered by the particle into a divergent beam lying substantially in the plane of polarization of the impinging light and within an angular range from about 30* to about 90* with respect to the forward direction of the impinging light.
Claim 3
Dependent Claim
17 words
The method set forth in clAim 1 and further including measuring the size of the individual particle.
Claim 4
Dependent Claim
28 words
The method set forth in claim 1, wherein said angular range extends from about 40* to about 70* with respect to the forward direction of said impinging light.
Claim 5
Independent Claim
101 words
A method of determining the absorption coefficients of multiple particles suspended in a fluid medium, comprising: impinging substantially plane-polarized light on a stream of said particles; measuring the intensity of the light scattered by said particles into a first divergent beam lying substantially in the plane of polarization of the impinging light and within an angular range from about 30* to about 90* with respect to the forward direction of said impinging light; and measuring the intensity of the light scattered by said particles into a second divergent beam the intensity of which is related to the total number of particles.
Claim 6
Independent Claim
101 words
A method of determining the absorption coefficients of multiple particles suspended in a fluid medium, comprising: impinging substantially plane-polarized light on a stream of said particles; measuring the intensity of the light scattered by said particles into a first divergent beam lying substantially in the plane of polarization of the impinging light and within an angular range from about 30* to about 90* with respect to the forward direction of said impinging light; and measuring the intensity of the light scattered by said particles into a second divergent beam the intensity of which is related to the total number of particles.
Claim 7
Dependent Claim
29 words
The method set forth in claim 4 and further including determining the ratio of the intensity of said first divergent beam to the intensity of said second divergent beam.
Claim 8
Dependent Claim
105 words
Apparatus responsive to the absorption coefficients of particles suspended in a fluid medium, comprising: a light scattering cell; means for projecting a beam of substantially collimated plane-polarized light through said cell; means for flowing a stream of substantially widely spaced individual particles in said medium through said cell; first means for collecting the rays scattered from said particles substantially into the plane of polarization of the projected beam and within an angular range from about 30* to about 90* with respect to the forward direction of said projected beam; and first means for measuring the intensity of said rays collected by said first collecting means.
Claim 9
Dependent Claim
105 words
Apparatus responsive to the absorption coefficients of particles suspended in a fluid medium, comprising: a light scattering cell; means for projecting a beam of substantially collimated plane-polarized light through said cell; means for flowing a stream of substantially widely spaced individual particles in said medium through said cell; first means for collecting the rays scattered from said particles substantially into the plane of polarization of the projected beam and within an angular range from about 30* to about 90* with respect to the forward direction of said projected beam; and first means for measuring the intensity of said rays collected by said first collecting means.
Claim 10
Dependent Claim
19 words
Apparatus as set forth in claim 6 and further including means for measuring the sizes of said individual particles.
Claim 11
Dependent Claim
28 words
Apparatus as set forth in claim 6, wherein said angular range extends from about 40* to about 70* with respect to the forward direction of said projected beam.
Claim 12
Dependent Claim
68 words
Apparatus as set forth in claim 6, wherein said flowing means is adapted to flow a stream of substantially closely spaced multiple particles through said cell; and second means for collecting the rays scattered from said particles into a beam the intensity of which is related to the total number of particles; and second means for measuring the intensity of said rays collected by said second collecting means.
Claim 13
Dependent Claim
25 words
Apparatus as set forth in claim 9 and further including means for determining the ratio of said first measured intensity to said second measured intensity.
References Cited (Backward Citations)
US3646352A
Cited
US3807862A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |