Glasses suitable for the segment of a multifocal lens have composition (wt%): 35-52 SiO2, 0-12 Na2O, 0-10 K2O (Na2O + K2O = 6-12), 28.1-34 BaO, 2-15 ZrO2, 0-10 CaO, 0-10 ZnO, 0-10 PbO (CaO + ZnO + PbO = 5-15). Alternatively the composition could include 0.5-5 TiO2. RI was 1.57-1.67, softening point at least 1385 degrees F, thermal expansion coefficient 70-100 between 25 and 300 degrees C. Data are tabulated for 13 glasses.
Origin
Unknown
Journal Title
Usp 3 178 274, 13/4/65
Sector
Refractive Indexes
Class
RI 31