| 摘要 |
An optical glass which is free of PbO which causes environmental pollution and also is free of expensive Ta2O5 and Nb2O5 comprises, in mass %,and has optical constants of a refractive index (nd) within a range from 1.55 to less than 1.67 and an Abbe number (nud) within a range from 30 to 45.
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