US3767306A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for detecting dust particles by partial embedment in a layer whose surface is deformed by the particles and measuring radiation scattered by the particles with a schieren optical system
Assignee: Gretag AG
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Filing: 1972-02-09
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Granted: 1973-10-23
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Expires: 1992-02-09
Abstract
Abstract A method and apparatus for detecting and measuring the number and/or size of dust particles on a support plate having a planar surface. The method comprising flowing a liquid layer over the support to wet the particles and controlling the layer thickness so that particles form deformations in the layer surface due to surface tension of the liquid and then measuring,by means of a Schlieren or phase contrast optical system, the amount of light scattered by those particles causing the deformations. The measured intensity is then compared with calibration curves derived empirically from measurements of dust particles of known size embedded in liquid layers of different known thicknesses to determine the number and/or size of the particles under measurement. The apparatus comprises a dust proof chamber into which the support plate with the particles embedded in a liquid layer is introduced, the chamber including a light source for illuminating the liquid layer and a Schlieren optical system for measuring the light scattered from the particles. The optical system includes a photoelectric transducer which is connected to an evaluation system not forming part of the housing to provide an indication of the number and/or size of the particles under measurement.
Inventors
- 👤 Roche U La
- 👤 J Knus
- 👤 F Mast
- 👤 R Rossi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:08
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/94; G01N15/00; G01N15/02; G01N15/0205
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
67 words
A method of detecting particles comprising the steps of depositing the particles on the surface of a support member, wetting the particles by flowing a liquid layer over said surface, the depth of said layer being less than the maximum height of said particles, projecting a beam of radiation onto said layer and measuring the radiation scattered by said particles by means of a Schlieren optical system.
Claim 2
Independent Claim
67 words
A method of detecting particles comprising the steps of depositing the particles on the surface of a support member, wetting the particles by flowing a liquid layer over said surface, the depth of said layer being less than the maximum height of said particles, projecting a beam of radiation onto said layer and measuring the radiation scattered by said particles by means of a Schlieren optical system.
Claim 3
Dependent Claim
67 words
A method according to claim 1, including empirically determining the relationship between different quantities of scattered radiation measured by said optical system for different predetermined number of particles of a given size embedded in layers of different thicknesses and relating the measurements to the scattered radiation received by said optical system from a layer having particles embedded therein to determine the number of particles and their size.
Claim 4
Dependent Claim
36 words
A method according to claim 2, including mounting said support member horizontally, allowing the liquid to evaporate and measuring the radiation scattered by said particles at different predetermined thicknesses of said layer as said liquid evaporates.
Claim 5
Dependent Claim
39 words
A method according to claim 1 wherein the step of wetting the particles on the surface of said support member is performed by flowing the liquid layer over said surface after the particles have been deposited on said surface.
Claim 6
Dependent Claim
45 words
A method according to claim 1 wherein the step of wetting the particles on the surface of said support member is performed by flowing a layer of liquid over the surface and which has a viscosity within the range of from 2 to 6 centipoises.
Claim 7
Dependent Claim
32 words
A method according to claim 1 wherein the step of wetting the particles on the surface of said support member is performed by flowing a layer of silicone oil over the surface.
Claim 8
Dependent Claim
67 words
A method according to claim 1 wherein the step of wetting the particles on the surface of said support member is performed by coating said surface with a layer of thermoplastic material, heating said thermoplastic layer subsequent to deposition thereon of the particles to be detected to a temperature sufficient to liquify the layer and wet the particles, and then permitting the layer to cool and re-solidify.
Claim 9
Dependent Claim
63 words
Apparatus for detecting particles comprising a source of radiation, a Schlieren optical system for receiving radiation, a support member, a layer formed on a surface of said member to receive and wet dust particles, and means for positioning said support member relative to said source and said optical system so that said layer acts as a radiation controlling layer for said optical system.
Claim 10
Dependent Claim
63 words
Apparatus for detecting particles comprising a source of radiation, a Schlieren optical system for receiving radiation, a support member, a layer formed on a surface of said member to receive and wet dust particles, and means for positioning said support member relative to said source and said optical system so that said layer acts as a radiation controlling layer for said optical system.
Claim 11
Dependent Claim
25 words
Apparatus according to claim 8, including means for spreading a liquid layer over the surface of said support member to wet dust particles deposited thereon.
Claim 12
Dependent Claim
12 words
Apparatus according to claim 8, wherein said layer is of thermoplastic material.
Claim 13
Dependent Claim
79 words
Apparatus for detecting particles comprising a housing, a light source and a Schlieren optical system within said housing, a support member having a planar surface, means for introducing said surface into said housing and means for applying a liquid layer to said surface to wet particles thereon, said optical system being positioned relative to said layer and said source so that light scattered by the deformations caused by the particles in said layer is measured by said optical system.
Claim 14
Dependent Claim
79 words
Apparatus for detecting particles comprising a housing, a light source and a Schlieren optical system within said housing, a support member having a planar surface, means for introducing said surface into said housing and means for applying a liquid layer to said surface to wet particles thereon, said optical system being positioned relative to said layer and said source so that light scattered by the deformations caused by the particles in said layer is measured by said optical system.
Claim 15
Dependent Claim
43 words
Apparatus according to claim 11, wherein said optical system includes a photoelectric device for receiving light scattered by said particles and said apparatus further includes an evaluating system coupled to said photoelectric device for determining the number of particles of a predetermined size.
Claim 16
Independent Claim
83 words
A method of detecting particles comprising the steps of embedding said particles in a substance lying on the surface of a support member whilst said substance is in a liquid phase, the depth of said liquid substance being less than the maximum height of said particles, projecting light into the surface of said substance and measuring by means of a Schlieren optical system the variation in the intensity of light resulting from deformations in the surface of said substance caused by said particles.
Claim 17
Independent Claim
83 words
A method of detecting particles comprising the steps of embedding said particles in a substance lying on the surface of a support member whilst said substance is in a liquid phase, the depth of said liquid substance being less than the maximum height of said particles, projecting light into the surface of said substance and measuring by means of a Schlieren optical system the variation in the intensity of light resulting from deformations in the surface of said substance caused by said particles.
Claim 18
Dependent Claim
30 words
A method according to claim 13 wherein the step of embedding said particles in the substance is performed by use of a substance which is normally in a liquid phase.
Claim 19
Dependent Claim
55 words
A method according to claim 13 wherein the step of embedding said particles in the substance is performed by coating the surface of said support member with a layer of thermoplastic material and heating said thermoplastic layer subsequent to deposition thereon of the particles to be detected to a temperature sufficient to liquify the layer.
Claim 20
Dependent Claim
48 words
A method according to claim 13 wherein the step of measuring the variation in intensity of light resulting from deformation in the surface of said substance caused by said particles is performed by projecting the light through the substance and the support member to said Schlieren optical system.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |