Patent US2661902A successfully refreshed from Google Patents.
US2661902A
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US
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Apparatus for counting microscopic particles
Assignee: NAT RES DEV
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Filing: 1951-01-10
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Granted: 1953-12-08
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Expires: 1971-01-10
Abstract
No abstract record available.
Inventors
- 👤 Wolff Heinz Siegfried
- 👤 Story Marjorie Grace
- 👤 Behrens Derick Jacob
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:20
CPC Classifications
G; G01; G01N; G01N15/00; G01N15/10; G01N15/14; G01N15/1468
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1974522A
Cited
US2037044A
Cited
US2073246A
Cited
US2088297A
Cited
US2369577A
Cited
US2413965A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-12-07 | 1957-06-08 | 1957-12-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-12-07 | 1961-06-08 | 1961-12-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-12-07 | 1965-06-08 | 1965-12-08 | $7700.00 | Window Closed / Lapsed |