| 摘要 |
PROBLEM TO BE SOLVED: To provide a preform for precision press molding including an optical glass having a wide dispersion characteristic, a low press temperature and a high stability and its manufacturing method, an optical device obtained by precision-press molding the preform and its manufacturing method. SOLUTION: The preform for precision press molding comprises an optical glass which contains by mole% 15-70% of P<SB>2</SB>O<SB>5</SB>, 1-30% of Nb<SB>2</SB>O<SB>5</SB>, 0-20% of TiO<SB>2</SB>(excluding 0%), 0-30% of Bi<SB>2</SB>O<SB>3</SB>(excluding 0% and over 4 wt.%), 0-30% of B<SB>2</SB>O<SB>3</SB>, 1-20% of WO<SB>3</SB>, 0-15% of BaO, 3-15% of Li<SB>2</SB>O (excluding 3 wt.%), 0-5% of SiO<SB>2</SB>(excluding 5 wt.%), and 0-10% of ZnO (excluding 10 wt.%) and has a weight ratio of less than 0.5 (TiO<SB>2</SB>content/Bi<SB>2</SB>O<SB>3</SB>content), a refractive index (nd) of≥1.7 and an Abbe's number (νd) of≤32. The optical device is manufactured from the preform. COPYRIGHT: (C)2009,JPO&INPIT
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