| 摘要 |
PURPOSE:To manufacture an optical fiber base material having a satisfactory refractive index distribution and a practical specific refractive index by burning starting material gases with an oxyhydrogen flame burner in which part of hydrogen is replaced with a gas burning at a temp. higher than that of hydrogen and by depositing the resulting glass fine powder. CONSTITUTION:Starting material gases are burned and hydrolyzed with an oxyhydrogen flame burner in which part of hydrogen is replaced with a gas burning in oxygen at a temp. higher than that of hydrogen. The resulting glass fine powder is deposited on a starting member in the axial direction to form a porous preform. Since there exists a fixed relation between the temp. and the reaction efficiency of Ge, by successively increasing the amount of C2H2 or the like replaced while measuring the surface temp. of the preform, a previously set Ge concn. can be attained and the specific refractive index can be adjusted to a desired value. The above-mentioned gas which reacts with 02 and burns at a temp. higher than that of H2 includes C2H2, C4H10 and (CN)2. |
