Patent US3871769A successfully refreshed from Google Patents.
US3871769A
Expired / Lapsed
US
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Apparatus for determining the diameters of small particles
Assignee: Turlabor AG
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Filing: 1973-05-18
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Granted: 1975-03-18
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Expires: 1993-05-18
Abstract
Abstract Apparatus for determining the diameters of small particles by means of coherent light being scattered thereby, including holographic filters for converting the scattered light waves received from the particles exactly into spherical light waves only when said particles are of a predetermined diameter, said light waves then being passed through a lens and apertured diaphragm into separate light-measuring devices, each of which is associated with respectively one of said filters and which emits an electrical signal proportional to the intensity of the received light such as said signal becomes maximum when the diameter of the illuminated particle equals the predetermined particle diameter.
Inventors
- 👤 Andreas Hermann Engel
- 👤 Gerd Bernd Herziger
- 👤 Theodor Heinrich Tschudi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:43
CPC Classifications
G; G01; G01N; G01N15/00; G01N15/02; G01N15/0205; G01N15/0211; G02; G02B; G02B27/00; G02B27/42; G02B27/46; G02B5/00; G02B5/32; G01N15/0227; G01N2015/0233
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
215 words
An apparatus for determining the diameters of small particles in which coherent light is scattered by said particles and the scattered light wavefronts are substituted with wavefronts previously recorded on hologram filters, wherein the improvement comprises first lens means for collecting said coherent light into a plurality of focal points, a sample of said particles being disposed in each of said focal points, at least one hologram filter positioned behind each of said focal points, said hologram filters each being adapted to convert the light waves scattered by particles of a predetermined different diameter into output light waves having a spherical wavefront, separate lightmeasuring means associated with each of said hologram filters for receiving said output light waves from each of said hologram filters, second lens means and apertured diaphragm means being interposed between said hologram filters and the light-measuring means associated therewith and having said output light waves pass therethrough, said light-measuring means each generating an electrical signal in response to said output light waves received from said hologram filters, said signal being linearly dependent upon the intensity of the light received and attaining a maximum value when the diameter of illuminated particle is equal to the predetermined particle diameter at which the respective hologram filter emanuates output light waves having a spherical wavefront.
Claim 2
Independent Claim
215 words
An apparatus for determining the diameters of small particles in which coherent light is scattered by said particles and the scattered light wavefronts are substituted with wavefronts previously recorded on hologram filters, wherein the improvement comprises first lens means for collecting said coherent light into a plurality of focal points, a sample of said particles being disposed in each of said focal points, at least one hologram filter positioned behind each of said focal points, said hologram filters each being adapted to convert the light waves scattered by particles of a predetermined different diameter into output light waves having a spherical wavefront, separate lightmeasuring means associated with each of said hologram filters for receiving said output light waves from each of said hologram filters, second lens means and apertured diaphragm means being interposed between said hologram filters and the light-measuring means associated therewith and having said output light waves pass therethrough, said light-measuring means each generating an electrical signal in response to said output light waves received from said hologram filters, said signal being linearly dependent upon the intensity of the light received and attaining a maximum value when the diameter of illuminated particle is equal to the predetermined particle diameter at which the respective hologram filter emanuates output light waves having a spherical wavefront.
Claim 3
Dependent Claim
12 words
An apparatus as claimed in claim 1, said hologram filters being sector-shaped.
Claim 4
Dependent Claim
48 words
An apparatus as claimed in claim 1, said first lens means comprising a Fresnel diffraction lens having at least two of said focal points, transparent capillary tube means being located in each focal point, said capillary tube means forming a flow passageway for a stream of said particles.
Claim 5
Dependent Claim
70 words
An apparatus as claimed in claim 3, comprising a support plate for said Fresnel diffraction lens; a plurality of further Fresnel diffraction lenses of reduced size being provided in said support plate; support plates for said hologram filters having marking apertured diaphragms, said further Fresnel diffraction lenses and said marking apertured diaphragms being adapted to be correlated for determining the exact spacial position between said lens and filter support plates.
Claim 6
Dependent Claim
54 words
An apparatus as claimed in claim 4, comprising a housing, said lens and filter support plates and said capillary tube means being located in said housing; an immersion fluid being contained in said housing, said immersion fluid having a refractive index corresponding to the refractive index of the material of said capillary tube means.
References Cited (Backward Citations)
US3601466A
Cited
US3666359A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-17 | 1978-09-16 | 1979-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-17 | 1982-09-16 | 1983-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-17 | 1986-09-16 | 1987-03-18 | $7700.00 | Window Closed / Lapsed |