US2660922A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Interference microscope
Assignee: National Research Development Corp UK
•
Filing: 1949-05-31
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Granted: 1953-12-01
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Expires: 1969-05-31
Abstract
No abstract record available.
Inventors
- 👤 Philpot John St Leger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 00:33
CPC Classifications
G; G02; G02B; G02B21/00; G02B21/06; G02B21/08; G02B21/14
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
DE239120C
Cited
DE355911C
Cited
US1470770A
Cited
US1573401A
Cited
GB474809A
Cited
US2265784A
Cited
GB555672A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-11-30 | 1957-06-01 | 1957-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-11-30 | 1961-06-01 | 1961-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-11-30 | 1965-06-01 | 1965-12-01 | $7700.00 | Window Closed / Lapsed |