| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a glass preform for an optical fiber having a uniform distribution of the refractive index in the radial direction by reducing the difference between the refractive index of a glass rod (starting rod) for a core having a portion of clad and the refractive index of a glass layer deposited on the rod by an OVD (Outside Vapor Deposition) method. <P>SOLUTION: In a method for manufacturing the glass preform for the optical fiber by transparently vitrifying a porous preform for the optical fiber obtained by the OVD method by sintering it, the porous preform is heat-treated in an atmosphere containing a dehydrated gas. Then, after cooling the preform for at least 10 h, the dehydrated gas is replaced with an inert gas, and the porous preform is transparently vitrified in vacuum or under reduced pressure. The replacement of the dehydrated gas with the inert gas is preferably performed after cooling for at least 24 h after heat treatment of the porous preform in the atmosphere containing the dehydrated gas. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
