| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical glass having a refractive index nd of≥1.87 and an Abbe's numberνd of not less than 35 and less than 40, having viscosity temperature dependency permitting the ready forming of a preform for precision press molding, affording good glass stability, and having low temperature melting properties permitting precision press molding with good productivity, a preform for precision press-molding comprising the optical glass, an optical element, and method for manufacturing the same. SOLUTION: The optical glass comprises, denoted as molar percentages, 0-20% SiO<SB>2</SB>, 5-40% B<SB>2</SB>O<SB>3</SB>, wherein SiO<SB>2</SB>+B<SB>2</SB>O<SB>3</SB>=15-50%, 0-10% Li<SB>2</SB>O, and 12-36% ZnO, wherein 3×Li<SB>2</SB>O+ZnO≥18%, 5-30% La<SB>2</SB>O<SB>3</SB>, 0-20% Gd<SB>2</SB>O<SB>3</SB>, 0-10% Y<SB>2</SB>O<SB>3</SB>, wherein La<SB>2</SB>O<SB>3</SB>+Gd<SB>2</SB>O<SB>3</SB>=10-30%, and wherein La<SB>2</SB>O<SB>3</SB>/ΣRE<SB>2</SB>O<SB>3</SB>=0.67-0.95, (whereinΣRE<SB>2</SB>O<SB>3</SB>=La<SB>2</SB>O<SB>3</SB>+Gd<SB>2</SB>O<SB>3</SB>+Y<SB>2</SB>O<SB>3</SB>+Yb<SB>2</SB>O<SB>3</SB>+Sc<SB>2</SB>O<SB>3</SB>+Lu<SB>2</SB>O<SB>3</SB>), 0.5-10% ZrO<SB>2</SB>, 1-15% Ta<SB>2</SB>O<SB>5</SB>, 1-20% WO<SB>3</SB>, wherein Ta<SB>2</SB>O<SB>5</SB>/WO<SB>3</SB>≤2.5 (molar ratio), 0-8% Nb<SB>2</SB>O<SB>5</SB>, and 0-8% TiO<SB>2</SB>, and has a refractive index nd of not less than 1.87, an Abbe's numberνd of not less than 35 and less than 40. A preform for precision press-molding comprising the glass, an optical element, and a method for manufacturing the same are also provided. COPYRIGHT: (C)2010,JPO&INPIT |
