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Patent US2687670A successfully refreshed from Google Patents.
US2687670A
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Optical device with a variable and colored phase contrast
Assignee: VENTE DES INSTR DE GEODESIE HE
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Filing: 1951-04-25
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Granted: 1954-08-31
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Expires: 1971-04-25
Abstract
No abstract record available.
Inventors
- 👤 Locquin Marcel Victor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:55
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)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1957-08-30 | 1958-03-01 | 1958-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-08-30 | 1962-03-01 | 1962-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-08-30 | 1966-03-01 | 1966-08-31 | $7700.00 | Window Closed / Lapsed |