Claims
- 1. Glass having a refractive index in the range of 1.70-1.78 and having compositions expressed in percentages by weight on an oxide basis, that consist essentially of:SiO227-36B2O30-9Li2O1-5Na2O1-7K2O0-7CaO0-7BaO 4-13ZnO0-8La2O3 4-15PbO 4-27TiO2 7-18ZrO20-9Nb2O50-8with:Li2O + Na2O + K2O 6-15SiO2 + TiO2 + ZrO242-55PbO + TiO2 + ZrO2 + Nb2O529-40
- 2. Glasses according to claim 1 having the following composition of oxides, expressed in percentages by weight, that consists essentially of:SiO228-35B2O32-9Li2O2-5Na2O2-6K2O0-5BaO 5-13ZnO0-7La2O3 4-14PbO10-27TiO2 9-15ZrO2 0-4.
- 3. A glass segment for a multifocal corrective lens, the lens having a refractive index in the range of 1.70-1.78 and having a composition in accordance with claim 1.
- 4. A glass segment in accordance with claim 3 having a softening point of 570°-620° C. and a thermal dilation coefficient of 90-110×110−7/° C.
- 5. A glass segment in accordance with claim 3 having a composition in accordance with claim 2.
- 6. A multifocal lens in accordance with claim 5 wherein the glass segment has a thermal dilation coefficient of 90-110×10−7/° C. and a softening point of 570-620° C.
- 7. A multifocal corrective lens comprising a principal glass lens having a refractive index lower than the refractive index of a glass segment incorporated in the principal glass lens, the glass segment having a refractive index in the range of 1.70-1.78 and having a composition in accordance with claim 1.
- 8. A multifocal lens according to claim 7 characterized in that the glass of said principal lens has the following characteristics:thermal dilation coefficient: 100×10−7 K−1 (between 25 and 300° C.); softening point: 610° C.; refractive index 1.6.
Priority Claims (1)
Number |
Date |
Country |
Kind |
97 05357 |
Apr 1997 |
FR |
|
Parent Case Info
This application is a 371 of PCT/US98/08352 filed Apr. 27, 1998 which claims the benefit of U.S. Ser. No. 60/051,538 filed Jul. 2, 1997.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
102e Date |
371c Date |
PCT/US98/08352 |
|
WO |
00 |
6/2/2000 |
6/2/2000 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO98/49110 |
11/5/1998 |
WO |
A |
US Referenced Citations (7)
Foreign Referenced Citations (5)
Number |
Date |
Country |
3002935 |
Oct 1980 |
DE |
2099417 |
Dec 1982 |
GB |
75-073914 |
Jun 1975 |
JP |
77-084211 |
Jul 1977 |
JP |
60-221338 |
Nov 1985 |
JP |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/051538 |
Jul 1997 |
US |