Patent ID: 7531475

Claim:
The glass composition consisting of the following components, indicated by mol %: 55 to 80 SiO 2 ; 5 to 25 Al 2 O 3 ; 0.01 to 5 bismuth oxide in terms of Bi 2 O 3 ; 0 to 15 Li 2 O; 0 to 5 Na 2 O; 0 to 5 K 2 O; 0 to 40 MgO; 0 to 30 CaO; 0 to 5 SrO; 0 to 5 BaO; 0 to 25 ZnO; 0 to 10 TiO 2 ; 0 to 5 ZrO 2 ; 0 to 10 B 2 O 3 ; 0 to 5 of at least one selected from the group consisting of Y 2 O 3 , La 2 O 3 , Ta 2 O 5 , Nb 2 O 5 , GeO 2 and In 2 O 3 ; 0 to 1 of at least one selected from the group consisting of As 2 O 3 , Sb 2 O 3 , SO 3 , SnO 2 , Fe 2 O 3 , CL and F, and wherein the total of MgO+CaO+SrO+BaO+ZnO is in a range of 0.1 to 40 mol %, and wherein the glass composition emits fluorescence in an infrared wavelength region through irradiation of excitation light, with bismuth contained in the bismuth oxide functioning as a fluorescent source.