| 摘要 |
A glass has a liquidus temperature of at least 80 DEG F. below the temperature at which the logarithm to the base 10 of the viscosity in poises is 5, refractive index below 1.5, fibre softening point below 1425 DEG F., and coefficient of thermal expansion of less than 80 x 10-7. The glass consists essentially of, by weight, 35-50% SiO2, 3-11% Al2O3, 22-38% B2O3 and 15-25% Rb2. The glass may form the matrix in which rods or fibres of a glass of different composition, e.g. 29.3% SiO2, 61.7% PbO and 8.0% BaO, are embedded. The composite structure may be formed by enclosing rods in tubes of the matrix-forming glass, assembling, heating and pulling, the resultant structure comprising many fine glass fibres in parallel orientation embedded in a matrix. For the purposes of fibre optics, the refractive index of the fibre glass should be greater than that of the matrix glass.
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