| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide optical glass that has a high refractive index and a low dispersibility and is excellent in press formability. <P>SOLUTION: The optical glass includes SiO<SB POS="POST">2</SB>, B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, Al<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, BaO, CaO, ZnO, La<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, Gd<SB POS="POST">2</SB>O<SB POS="POST">3</SB>and Y<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, each in a prescribed ratio. Further, the optical glass satisfies the following conditional expressions (1) and (2), taking the content of SiO<SB POS="POST">2</SB>as A, the content of B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>as B, the content in total of La<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, Gd<SB POS="POST">2</SB>O<SB POS="POST">3</SB>and Y<SB POS="POST">2</SB>O<SB POS="POST">3</SB>as C, and the content in total of SiO<SB POS="POST">2</SB>and B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>as D: (1) 0.35<A/B<0.70, (2) 0.80<C/D<1.0. By the constitution, a high refractive index and a low dispersibility are secured and at the same time deformation temperature (and glass transition temperature) lowers. By containing Al<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, the glass structure is stabilized and a failure in appearance such as cloudiness in press molding is difficult to occur. <P>COPYRIGHT: (C)2012,JPO&INPIT |
