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Patent US3666347A successfully refreshed from Google Patents.
US3666347A
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US
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Spherical lens structures
Assignee: Nippon Selfoc Kk Also Known As
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Filing: 1970-03-10
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Granted: 1972-05-30
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Expires: 1990-03-10
Abstract
Abstract A GLASS SPHERE CONTAINING THALLIUM AND SODIUM CATIONS IS IMMERSED IN A BATH OF A MOLTEN SALT CONTAINING AT LEAST ONE KIND OF METAL CATIONS SUCH AS POTASSIUM CATIONS TO CAUSE ION EXCHANGE THROUGH THE GLASS CONTACT SURFACE IN A MANNER SUCH THAT THE CONCENTRATION OF THE CATIONS, WHICH CONSTITUTE MODIFYING OXIDES WITHIN THE GLASS, VARY FROM THE CENTER TOWARD THE OUTER SURFACE OF THE SPHERE, WHICH THEREUPON BECOMES A SPHERICAL LENS WITH A REFRACTIVE INDEX N REPRESENTABLE BY WHEREIN N IS THE REFRACTIVE INDEX AT A RADIAL DISTANCE R FROM THE CENTER, N0 IS THE REFRACTIVE INDEX AT THE CENTER, A IS A POSITIVE CONSTANT, AND (R/A) IS LESS THAN ONE (UNITY).
Inventors
- 👤 Ichiro Kitano
- 👤 Hiroyoshi Matsumura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 18:23
CPC Classifications
G; G02; G02B; G02B3/00; G02B3/0087; C; C03; C03C; C03C21/00; C03C21/001
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-30 | 1975-11-29 | 1976-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-30 | 1979-11-29 | 1980-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-30 | 1983-11-29 | 1984-05-30 | $7700.00 | Window Closed / Lapsed |