| 摘要 |
PROBLEM TO BE SOLVED: To provide a high refractive index-lower to middle dispersion type optical glass composition that has nd within a high refractive index range of 1.83-1.86 and νd within a range of 43-46, and yet shows excellent melting property, processability (droplet property), crystallinity and the like. SOLUTION: The optical glass composition contains, in % by mole, 0-10.0% SiO<SB>2</SB>, 35.0-45.0% B<SB>2</SB>O<SB>3</SB>, 0-5.0% Li<SB>2</SB>O, 0-12.0% ZnO, 0-10.0% ZrO<SB>2</SB>, 10.0-20.0% La<SB>2</SB>O<SB>3</SB>, 3.0-10.0% Ta<SB>2</SB>O<SB>5</SB>, 10.0-22.0% Ta<SB>2</SB>O<SB>5</SB>+ZnO and 5.0-20.0% Gd<SB>2</SB>O<SB>3</SB>, and has a refractive index (nd) to the d-line of 1.83-1.86, an Abbe number (νd) to the d-line of 43-46 and a liquidus temperature of ≤1,200°C. A preform and an optical element are also provided. COPYRIGHT: (C)2010,JPO&INPIT
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