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US3471213A
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US
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Long range varifocal optical systems
Assignee: Individual
•
Filing: 1965-01-28
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Granted: 1969-10-07
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Expires: 1985-01-28
Abstract
No abstract record available.
Inventors
- 👤 Frank G Back
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 10:30
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/142
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US3386330A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-10-06 | 1973-04-07 | 1973-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-10-06 | 1977-04-07 | 1977-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-10-06 | 1981-04-07 | 1981-10-07 | $7700.00 | Window Closed / Lapsed |