US 7,528,083 B2
Optical glass
Koji Shimizu, Sagamihara (Japan); and Susumu Uehara, Sagamihara (Japan)
Assigned to Kabushiki Kaish Ohara, Kanagawa-ken (Japan)
Filed on Jun. 02, 2004, as Appl. No. 10/859,435.
Claims priority of application No. 2003-164840 (JP), filed on Jun. 10, 2003.
Prior Publication US 2005/0026768 A1, Feb. 03, 2005
Int. Cl. C03C 3/062 (2006.01); C03C 3/097 (2006.01)
U.S. Cl. 501—73  [501/63] 44 Claims
 
1. An optical glass having a refractive index (nd) within a range from 1.825 to 1.870, an Abbe number (νd) within a range from 22 to less than 27, a transformation temperature (Tg) within a range from 530° C. to 585° C. and a mean coefficient of linear thermal expansion (α) within a range from 80×10−7° C.−1 to 103×10−7° C.−1, comprising SiO2, TiO2, Nb2O5 and Li2O and being substantially free of a Pb compound comprising, calculated on oxide basis and expressed in mass %;
   
  SiO2 18-36%
  TiO2  6-less than 18%
  Nb2O5 more than 42% and 55% or below
  where Nb2O5/TiO2 is 2.7 or over, and
  Li2O  2-8%.