| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of producing an optical fiber preform responding a production of a large-sized optical fiber preform when producing the optical fiber preform by an outside deposition method such as OVD method, and transparently vitrifying a silica glass porous body without causing cracking, delamination, dislocation or the like of glass in the effective part. SOLUTION: The method for producing optical fiber preform comprises: a process of preparing a porous glass preform 1 having a valid portion 10 to be used for the production of optical fiber and a first invalid portion 11 and a second invalid portion 12 adjacent to both end sides by depositing a silica glass porous body 5 on the outer periphery of a glass rod 2, a first dummy rod 3 and a second dummy rod 4; and transparently vitrifying the silica glass porous body 5 by heat treating the porous glass preform 1, wherein during the vitrification, at least one position in either or both of the first invalid portion 11 and the second invalid portion 12 in the silica glass porous body 5 is dislocated relative to the first dummy rod 3 or the second dummy rod 4 along the center axial direction of the glass rod such that stress between the glass rod 2 and the silica glass porous body 5 is relaxed. COPYRIGHT: (C)2010,JPO&INPIT
|
