| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a porous preform for optical fiber, which is capable of uniformly depositing glass particles onto the porous base material regardless of the occurrence of the resonance during producing the porous base material for the optical fiber, thereby the longitudinal change in the refractive index distribution of the preform for the optical fiber is suppressed to the minimum, and to provide a production apparatus. SOLUTION: The method for producing a porous preform for optical fiber having core/clad structure is comprised of supplying at least glass raw material gas, combustible gas and co-combustible gas to each of a burner for core and a burner for clad, hydrolyzing the glass raw material in oxyhydrogen flame of the burner to form glass particles and continuously depositing the glass particles from the top part of a rotating rod-shaped member to its axial direction. In this case, the static deflection amountδof the rod-shaped member is controlled to be not more than a/15, wherein a is the outside diameter of the deposited surface at the top part of the porous preform for the optical fiber during deposition. |
