| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a porous preform capable of stably doping a core soot 5a with a dopant and preventing occurrence of soot undulation. <P>SOLUTION: The surface temperature distribution of a leading end part 5b of a core soot 5a is measured, and the problem can be solved by (1) setting the surface temperature Tc of the center point c of the leading end part 5b of the core soot 5a within 500-1,000°C, preferably within 600-950°C, and/or (2) setting the difference Tm-Tc within 5-45°C, wherein Tm is the maximum of the surface temperatures at the leading end 5b of the core soot 5a and Tc is the surface temperature of the center point c of the leading end part 5b of the core soot 5a, and/or (3) setting the proportion R of the region in which the surface temperatures of the leading end 5b of the core soot 5a are higher than the surface temperature Tc of the center point c of the leading end part 5b of the core soot 5a within 5-30%. <P>COPYRIGHT: (C)2004,JPO</p> |
