| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical glass having high refractiveness and low dispersiveness, a low glass transition temperature (Tg), and an excellent internal quality. SOLUTION: The optical glass has a refractive index (n<SB>d</SB>) and Abbe number (ν<SB>d</SB>) within a range enclosed with a border line consisting of straight lines connecting point A (n<SB>d</SB>=1.75;ν<SB>d</SB>=50.0), point B (n<SB>d</SB>=1.80;ν<SB>d</SB>=46.0), point C (n<SB>d</SB>=1.80;ν<SB>d</SB>=50.0), point D (n<SB>d</SB>=1.75;ν<SB>d</SB>=56.0) and the point A in the order, the point B, the point C, the point D, and the point A in x-y rectangular coordinates in which x coordinate represents an Abbe number (ν<SB>d</SB>) and y coordinate represents a refractive index (n<SB>d</SB>), including a refractive index (n<SB>d</SB>) and an Abbe number (ν<SB>d</SB>) on the border line except for the straight line connecting the point A with the point D and the straight line connecting the point B with the point C, contains, as essential components, SiO<SB>2</SB>, B<SB>2</SB>O<SB>3</SB>, La<SB>2</SB>O<SB>3</SB>, Gd<SB>2</SB>O<SB>3</SB>, Li<SB>2</SB>O, and F and is substantially free of As<SB>2</SB>O<SB>3</SB>. COPYRIGHT: (C)2005,JPO&NCIPI
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