| 摘要 |
<p>The invention provides an optical glass having a very high refractive index in spite of its low-dispersion property, having excellent glass stability and having less susceptibility to coloring. An optical glass is an oxide glass and is characterized in that the optical glass comprises, by cationic %, 0 to 30% of Si<4>, 10 to 55% of B<3>, less than 5% of total of Li<>, Na<> and K<>, less than 5% of total of Mg<2>, Ca<2> and Sr<2>, 0 to 8% of Ba<2>, 0.1 to 15% of Zn<2>, 10 to 50% of La<3>, 0 to 20% of Gd<3>, 0 to 15% of Y<3>, 0 to 10% of Yb<3>, 0 to 20% of Zr<4>, 0.1 to 22% of Ti<4>, 0 to 20% of Nb<5>, 0 to 8% of Ta<5>, 0 to 5% of W<6>, 0 to 8% of Ge<4>, 0 to 10% of Bi<3>, and 0 to 10% of Ai<3>, the cationic ratio of the content of Si<4> to the content of B<3>, Si<4>/B<3>, being less than 1.0, the total content of Nb2O5 and Ta2O5 as oxides being less than 14 mass %, the optical glass having a refractive index nd of 1.92 to 2.2 and an Abbe's number nud of 25 to 45.</p> |
