| 摘要 |
PROBLEM TO BE SOLVED: To obtain a preform ingot having excellent optical characteristics and to provide a method for producing the preform ingot by which the surface of the preform ingot obtained by sintering and vitrifying a soot material having unevennesses formed on the surface by high-speed deposition is smoothly ground and worked so as not to decenter a core part and the surface unevennesses are removed. SOLUTION: This method is characterized as smoothly working the outer peripheral surface near both ends of the preform ingot 21, mounting the resultant ingot 21 on a grinding machine and preventing the positional shift during the working when depositing glass microparticles produced by a flame hydrolytic reaction on a starting core member 1, forming a clad part, sintering and vitrifying the soot material, then grinding the unevennesses caused on the surface of the resultant preform ingot 21 and removing the unevennesses. |
