| 摘要 |
PROBLEM TO BE SOLVED: To provide a cover glass for optical semiconductors having enough transmittance of blue laser beam light with short wave length of semiconductors. SOLUTION: The cover glass for an optical semiconductor comprises, by mass, 62-75% of SiO2 , 4-10% of Al2 O3 , 8-15% of B2 O3 , 7-20% of R2 O (R are Li, Na, and K), 0-3% of Li2 O, 10-12.5% of Na2 O, 0-2% of K2 O, 0.3-15% of R'O (R' are Mg, Ca, Ba, and Zn), 0-10% of MgO, 0-10% of CaO, 0-0.4% of BaO, 0.3-5% of ZnO, and 50 ppm or less of Fe2 O3 , and has 0.5 mm of thickness and 90% or more of transmittance at 300-600 nm of wave length.
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