| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical glass having optical constants of 1.50 to 1.60 refractive index (nd) and 60 to 75 Abbe' number (ν) and excellent permeability in ultraviolet light range. SOLUTION: This optical glass comprises 50-80 wt.% of P2 O5 1-5 wt.% of SiO2 , 5 20 wt.% of Al2 O3 , 0-5 wt.% of B2 O3 0-20 wt.% of R<1> 2 O 0-40 wt.% of R<2> O, 0.1-0.5 wt.% of As2 O3 or Sb2 O3 and 1-5 wt.% of F2 (R<1> 2 O is at least one selected from the group of Li2 O, Na2 O and K2 O or a combination of two or more of them; R<2> O is at least one selected from the group of MgO, CaO, SrO, BaO and ZnO or a combination of two or more of them; F2 (fluorine) exists as a fluoride in an oxide in which a part of oxygen ion of the oxide is substituted with fluorine ion). The optical glass has 1.5-1.6 refractive index and 60-75 Abbe's number and excellent transmission in an ultraviolet ray range.
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