US 7,572,746 B2
Optical glass
Junko Ishioka, Sagamihara (Japan); and Masahiro Onozawa, Sagamihara (Japan)
Assigned to Kabushiki Kaisha Ohara, Kanagawa-Ken (Japan)
Filed on Aug. 24, 2004, as Appl. No. 10/925,017.
Claims priority of application No. 2003-316915 (JP), filed on Sep. 09, 2003.
Prior Publication US 2005/0054514 A1, Mar. 10, 2005
Int. Cl. C03C 3/078 (2006.01)
U.S. Cl. 501—72  [501/65; 501/66; 501/67] 3 Claims
 
1. An optical glass having optical constants of refractive index (nd) within a range from 1.49 to 1.54 and Abbe number (ν d) within a range from 55 to 65 and comprising, in mass %,
 
SiO2 >65-75%
R2O (R is at least one selected from the group  15-25%
consisting of Li, Na, K and Cs)
where Li2O  0.1-5.0%
Na2O  1.0-10.0%
K2O  12.6-20.0% and
Cs2O  0-5.0%
R′O (R′ is at least one selected from the group  0.5-10%
consisting of Mg, Ca, Sr and Ba)
where MgO  0-10% and/or
CaO  0-10% and/or
SrO  0-10% and/or
BaO  0-10%
B2O3  0-6.0% and/or
Al2O3  0-<1.0% and/or
TiO2  0-1.69% and/or
ZrO2  0-2.0% and/or
WO3  0-3.0% and/or
Sb2O3  0-2.0% and
 
and comprising no ZnO or F except for an impurity mixed by inevitable mixing.