| 摘要 |
938,714. Optical glass. ERNST LEITZ G.m.b.H. June 30, 1961 [July 23, 1960], No. 23723/61. Class 56. Optical silico-borate glass comprises SiO 2 + B 2 O 3 23-43% mol., the molar ratio of silicic oxide to boric oxide being preferably 1.5, and the boric oxide content less than 29% mol., one or more oxides of Mg, Ca, Sr, Ba 13-10% mol., the content of BaO being less than 17% mol., ZnO/or CdO + ZnO 19-46% mol. with ZnO more than 17% mol., and ZrO 2 4.5-7.5% mol. Al 2 O 3 may replace SiO 2 + B 2 O 3 up to 8% mol. The alkaline earths may be added as fluorides. Optional constituents include in per cent mol. In 2 O 3 0-3.0, Y 2 O 3 and/or La 2 O 3 , 0-3.5, SnO 2 , 0-1.5, TiO 2 0-6.5, PbO 0-1.5, Ta 2 O 3 and/or Nb 2 O 5 0-2.0, WO 3 0-2.5. When Al 2 O 3 is present, the ratio of Al 2 O 3 to the sum of SiO 2 and B 2 O 3 is less than 0.275, the content SiO 2 + B 2 O 3 being not less than 28% mol. Specification 886,563 is referred to. |
