US4037964A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for measuring the sum of the radii of particles in a collection
Assignee: Leeds and Northrup Co
•
Filing: 1976-01-15
•
Granted: 1977-07-26
•
Expires: 1996-01-15
Abstract
Abstract There is disclosed a Fraunhofer plane spatial filter design for use in filtering the forward scattered light from a collection of particles to obtain an indication of the sum of the radii of the particles as a direct function of the total diffracted light flux passed by the filter.
Inventors
- 👤 Alan Lee Wertheimer
- 👤 Frederick Lee Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:38
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: 5
Claim 1
Independent Claim
200 words
A spatial filter for the Fraunhofer plane of a lens of 7.6 in. focal length for filtering the forward scattered light diffracted from a collection of particles lying in the path of a light beam of 0.6328μ wavelength for passing an amount of light flux directly related to the sum of the radii of the particles lying in the path of said beam comprising, an opaque mask having a transparent area therein which is made up of two separate zones wherein the inner radius of each of the zones is r 1 , the outer radius is r 2 , the inner angle is θ 1 , and the outer angle is θ 2 and the exponent of the filter function is P with the transparent opening being described by the table: ______________________________________
r.sub.1 θ.sub.1
r.sub.2
(θ.sub.2)
P
Inner Inner Outer Outer Exponent
Zone Radius Angle Radius Angle of
No. (Inches) (Degrees) (Inches)
(Degrees)
Filter Fn.
______________________________________
1 .1650 3.424 .6500 20.774 1.315
2 .6500 28.630 1.3400 89.793 1.580
______________________________________ with the boundaries of the transparent area between the inner and outer radius in each of the zones being in accordance with the equation: θ.sub.i = θ.sub.1 (r.sub.i /r.sub. 1).sup.P.
Claim 2
Dependent Claim
200 words
A spatial filter for the Fraunhofer plane of a lens of 7.6 in. focal length for filtering the forward scattered light diffracted from a collection of particles lying in the path of a light beam of 0.6328μ wavelength for passing an amount of light flux directly related to the sum of the radii of the particles lying in the path of said beam comprising, an opaque mask having a transparent area therein which is made up of two separate zones wherein the inner radius of each of the zones is r 1 , the outer radius is r 2 , the inner angle is θ 1 , and the outer angle is θ 2 and the exponent of the filter function is P with the transparent opening being described by the table: ______________________________________
r.sub.1 θ.sub.1
r.sub.2
(θ.sub.2)
P
Inner Inner Outer Outer Exponent
Zone Radius Angle Radius Angle of
No. (Inches) (Degrees) (Inches)
(Degrees)
Filter Fn.
______________________________________
1 .1650 3.424 .6500 20.774 1.315
2 .6500 28.630 1.3400 89.793 1.580
______________________________________ with the boundaries of the transparent area between the inner and outer radius in each of the zones being in accordance with the equation: θ.sub.i = θ.sub.1 (r.sub.i /r.sub. 1).sup.P.
Claim 3
Dependent Claim
104 words
apparatus for measuring the sum of the radii of the individual particles of a collection of particles comprising: means for directing a light beam at said collection of particles, a filter for filtering the light diffracted from said beam by the particles of said collection, said filter having a filter function which varies between approximately 1.3 and 1.6 as the distance from the axis of said beam increases so that the magnitude of the total light flux transmitted is proportional to said sum, and means for detecting the magnitude of the total light flux transmitted by said filter as a measure of said sum.
Claim 4
Dependent Claim
104 words
apparatus for measuring the sum of the radii of the individual particles of a collection of particles comprising: means for directing a light beam at said collection of particles, a filter for filtering the light diffracted from said beam by the particles of said collection, said filter having a filter function which varies between approximately 1.3 and 1.6 as the distance from the axis of said beam increases so that the magnitude of the total light flux transmitted is proportional to said sum, and means for detecting the magnitude of the total light flux transmitted by said filter as a measure of said sum.
Claim 5
Dependent Claim
41 words
Apparatus as set forth in claim 2 in which the filter function is 1.315 in the zone nearest the center of the filter and is 1.58 in the zone extending from the nearest zone to the outer limit of the mask.
References Cited (Backward Citations)
US3809478A
Cited
US3873206A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-25 | 1981-01-24 | 1981-07-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-25 | 1985-01-24 | 1985-07-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-25 | 1989-01-24 | 1989-07-26 | $7700.00 | Window Closed / Lapsed |