| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing a porous preform for an optical fiber, in which the fluctuation in the depositing amount of glass fine particles in the longitudinal direction is small. SOLUTION: When one end of a core preform for the optical fiber is defined as B, a part nearest to the point B of a chamber, being on the extended line of the axis of a starting material, is defined as A, the other end of the core preform for the optical fiber is defined as C, and a part nearest to the point C of the chamber, being on the extended line of the axis of the starting material is defined as D, and further, when the distance between the point A and the point B is defined as D1 , the distance between the point C and the point D is defined as D2 , and the distance between the point B and the point C, that is, the distance is the length of the core preform for the optical fiber is defined as LE, the starting material is arranged in the chamber so that the value of (D1 -D2 )/LE becomes -0.15 to 0.15. Furthermore, when the distance from the point A to the point D is defined as LC, the fluctuation in the deposition amount of the glass fine particles can further be suppressed to be small by setting LC/LE to be >=1.8.</p> |
