| 摘要 |
An optical glass has optical constants which are an refractive index (nd) of 1.70-1.75 and an Abbe number (vd) of 45.0-54.0; a glass transformation temperature (Tg) of 500-580° C. The glass has the following composition in mass percent of: SiO<SUB>2 </SUB>more than 5-15%; B<SUB>2</SUB>O<SUB>3 </SUB>20-less than 30%; a total amount of SiO<SUB>2</SUB>+B<SUB>2</SUB>O<SUB>3 </SUB>more than 25-40%; La<SUB>2</SUB>O<SUB>3 </SUB>more than 21-less than 30%; Y<SUB>2</SUB>O<SUB>3 </SUB>more than 5-15%; Gd<SUB>2</SUB>O<SUB>3 </SUB>0-less than 10%; ZrO<SUB>2 </SUB>1-8%; Nb<SUB>2</SUB>O<SUB>5 </SUB>0.1-5%; Ta<SUB>2</SUB>O<SUB>5 </SUB>more than 5-12%; a total amount of ZrO<SUB>2</SUB>+Nb<SUB>2</SUB>O<SUB>5</SUB>+Ta<SUB>2</SUB>O<SUB>5 </SUB>7-20%; ZnO 0-10%; CaO 0-10%; SrO 0-5%; BaO 0-10%; a total amount of ZnO+CaO+SrO+BaO 5-15%; Li<SUB>2</SUB>O 1-8%; Sb<SUB>2</SUB>O<SUB>3 </SUB>0-1%; and As<SUB>2</SUB>O<SUB>3 </SUB>0-1%. The glass is substantially free of Yb<SUB>2</SUB>O<SUB>3 </SUB>and Al<SUB>2</SUB>O<SUB>3</SUB>. Devitrification is not generated when the optical glass is kept at a temperature of 920° C. for two hours.
|
