| 摘要 |
1,235,401. Fibre glass compositions. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 26 June, 1969 [29 June, 1968; 1 April, 1969], No. 32373/69. Heading C1M. A glass consists of, in weight per cent: B 2 O 3 19-22 La 2 O 3 34-38 Al 2 O 3 2-5 ZrO 2 6-9 Nb 2 O 5 8-15 Ta 2 O 5 4-12 ThO 2 8-20 BaO 0-6 TiO 2 0-3. The glass, which has a refractive index of at least 1À81, may be used as the core glass in an optical fibre. A rod of the glass may be disposed in a tube of glass of lower refractive index and differing coefficient of thermal expansion and the assembly drawn at 750-800‹ C. to give fibres of diameter approximately 300 Á, the fibres then being bundled and redrawn to form a multifibre.
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