| 摘要 |
PROBLEM TO BE SOLVED: To provide an SiO<SB>2</SB>-R<SB>2</SB>O-RO-based optical glass used for various optical members such as an interchangeable lens and the like having such optical constants as a refractive index (nd) of 1.49-1.54 and an Abbe's number (νd) of 55-65. SOLUTION: The optical glass comprises by mass% >65-75% SiO<SB>2</SB>, 15-25% R<SB>2</SB>O (wherein, R is Li, Na, K and Cs; but Li<SB>2</SB>O is 0.1-5.0%; Na<SB>2</SB>O is 1.0-10.0%; K<SB>2</SB>O is 5.0-20.0%; Cs<SB>2</SB>O is 0-5.0%), 0.5-10% R'O (wherein, R' is Mg, Ca, Sr and Ba; but MgO, CaO, SrO and BaO are 0-10% respectively), furthermore, 0-6.0% B<SB>2</SB>O<SB>3</SB>, 0-<1.0% Al<SB>2</SB>O<SB>3</SB>, 0-<3.0% ZnO, 0-<2.0% TiO<SB>2</SB>, 0-2.0% ZrO<SB>2</SB>, 0-3.0% WO<SB>3</SB>, 0-2.0% Sb<SB>2</SB>O<SB>3</SB>and 0-2% F in fluorides by which a part or all of one or more kinds of above oxides are displaced. COPYRIGHT: (C)2005,JPO&NCIPI
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