| 摘要 |
PROBLEM TO BE SOLVED: To provide optical glass for precision forming which can be subjected to precision press forming at low temperatures, and has excellent mass- productivity. SOLUTION: The optical glass for precision press forming has a composition containing, by weight, 0.5 to 5% SiO<SB>2</SB>, 16 to 29% B<SB>2</SB>O<SB>3</SB>, 13 to 30% La<SB>2</SB>O<SB>3</SB>, and 6 to 20% Gd<SB>2</SB>O<SB>3</SB>; wherein the total content of La<SB>2</SB>O<SB>3</SB>and Gd<SB>2</SB>O<SB>3</SB>is 23 to 40%, 3 to 15% Ta<SB>2</SB>O<SB>5</SB>, 0.5 to 4% Li<SB>2</SB>O, 14 to 32% ZnO, 0 to 6% ZrO<SB>2</SB>, 5.5 to 12% WO<SB>3</SB>, and 0 to 6% Nb<SB>2</SB>O<SB>5</SB>, has a high index of refraction (nd) of 1.78 to 1.82, and an Abbe's number (νd) of 40.0 to 42.0, and has high refractory and low dispersibility. COPYRIGHT: (C)2003,JPO
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