Patent ID: 7005187

Claim:
Glass for a light filter having a coefficient of thermal expansion within a range from 90×10 −7 /° C. to 120×10 −7 /° C. within a temperature range from −20° C. to +70° C. and having a composition which comprises, in weight percent: one or more ingredients selected from the group consisting of SiO 2 , B 2 O 3 and P 2 O 5 in the total amount of 35-55%, wherein the upper limit of SiO 2 is 41.5%; one or more ingredients selected from the group consisting of TiO 2 , La 2 O 3 , ZrO 2 , Nb 2 O 5 , Ta 2 O 5 , WO 3 and Y 2 O 3 in the total amount of 20-45%, wherein TiO 2 is included within a range from 0 to 30% and ZrO 2 is included within a range from 0 to 5%; one or more ingredients selected from the group consisting of MgO, SrO, BaO and ZnO in the total amount of 3-20%; Na 2 O within a range from 0 to 14.5%; and one or both of Sb 2 O 3 and As 2 O 3 in the total amount of 0-1%, said glass being substantially free of Al 2 O 3 , CdO, CaO and PbO.