| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide optical glass capable of satisfying all of following requirements: (1) the optical glass does not substantially contain environmentally unfavorable components; (2) the optical glass has a low glass transition point; (3) the optical glass has a high refractive index and low dispersion; and (4) the optical glass is excellent in devitrification resistance when forming preform glass. <P>SOLUTION: The optical glass is characterized by including, in mass% as glass compositions, 0-21% SiO<SB POS="POST">2</SB>, 6.5-30% B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, 0-15.5% ZnO, 0-8% ZrO<SB POS="POST">2</SB>, 36.6-65% La<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, 0-16% Gd<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, 1-18% Ta<SB POS="POST">2</SB>O<SB POS="POST">5</SB>, 0 to less than 8% Nb<SB POS="POST">2</SB>O<SB POS="POST">5</SB>, 0.1-25% WO<SB POS="POST">3</SB>and 0.1-5% Li<SB POS="POST">2</SB>O, having a refractive index of 1.86 or more and substantially not containing lead, arsenic and F components. <P>COPYRIGHT: (C)2013,JPO&INPIT |
