Optical glass

Abstract

Provided is an optical glass having a high refractive index and high light transmittance. The optical glass contains, in terms of mol % based on oxides, SiO2: 9.0% to 11.0%, B2O3: 22.0% to 24.0%, La2O3: 18.0% to 20.0%, and TiO2: 30.0% to 31.0%.

1 . An optical glass comprising, in terms of mol % based on oxides:
 SiO 2 : 9.0% to 11.0%;   B 2 O 3 : 22.0% to 24.0%;   La 2 O 3 : 18.0% to 20.0%; and   TiO 2 : 30.0% to 31.0%.   
     
     
         2 . The optical glass according to  claim 1 , further comprising, in terms of mol % based on oxides:
 Y 2 O 3 : 3.0% to 5.0%;   WO 3 : 0.1% to 0.4%;   Nb 2 O 5 : 2.5% to 4.0%;   ZrO 2 : 5.0% to 8.0%; and   Gd 2 O 3 : 3.0% to 5.0%.   
     
     
         3 . The optical glass according to  claim 2 , satisfying, in terms of mol % based on oxides:
 SiO 2 : 9.0% to 10.0%;   B 2 O 3 : 22.5% to 23.5%;   Y 2 O 3 : 3.5% to 4.5%;   TiO 2 : 30.3% to 30.7%;   WO 3 : 0.2% to 0.3%;   Nb 2 O 5 : 3.0% to 3.5%;   La 2 O 3 : 18.5% to 19.5%;   ZrO 2 : 6.0% to 7.0%; and   Gd 2 O 3 : 3.5% to 4.5%.   
     
     
         4 . The optical glass according to  claim 1 , having a composition in a range of 99.5%≤(SiO 2 +B 2 O 3 +Y 2 O 3 +TiO 2  +WO 3 +Nb 2 O 5 +La 2 O 3 +ZrO 2 +Gd 2 O 3 )≤100.0%, in terms of mol % based on oxides. 
     
     
         5 . The optical glass according to  claim 1 , having a refractive index in a range of 1.90 to 2.10. 
     
     
         6 . The optical glass according to  claim 1 , having an internal transmittance at 450 nm of 88.0% or higher. 
     
     
         7 . The optical glass according to  claim 1 , having a devitrification temperature T in a range of T <1,170° C.