Optical fiber manufacture method, preform manufacture method, and preform manufacture apparatus

Abstract

A method for manufacturing an optical fiber comprises setting a heating condition for heating a glass rod, which is a parent material of the optical-fiber, and an elongating speed of the glass rod based on a prescribed numerical value which changes with a progress of elongation of the glass rod; heating and elongating the glass rod to generate a preform based on the heating condition and the elongating speed which are set by the setting; and drawing the preform to a filament-like form by further heating the preform to generate the optical fiber.

1 - 11 . (canceled)  
   
   
       12 . A method for manufacturing an optical fiber comprising: 
 first elongating a glass base material in a vertical direction to produce a glass rod;    second elongating said glass rod to produce a preform, wherein said second elongating includes controlling heating said glass rod and controlling an elongating speed of said glass rod, based on a tensile stress generated on said glass rod during second elongating;    heating and elongating said glass rod in the horizontal direction; and    drawing said preform to a filament-like form by further heating said preform to generate said optical fiber,    wherein a heating source, which heats said glass rod, moves in along a longitudinal direction of said glass rod with a progress of said second elongating, and    wherein said heating and elongating are controlled so that said tensile stress before said heating source moves a prescribed distance becomes substantially 110 percent or below an average value of said tensile stress after said heating source moves said prescribed distance.    
   
   
       13 . A method for manufacturing an optical fiber comprising: 
 first elongating a glass base material in a vertical direction to produce a glass rod;    second elongating said glass rod to produce a preform, wherein said second elongating includes controlling heating said glass rod and controlling an elongating speed of said glass rod, based on a tensile stress generated on said glass rod during second elongating;    heating and elongating said glass rod in the horizontal direction; and    drawing said preform to a filament-like form by further heating said preform to generate said optical fiber,    wherein a heating source, which heats said glass rod, moves in along a longitudinal direction of said glass rod with a progress of said second elongating, and    wherein said heating and elongating are controlled so that tensile stress before said heating source moves said prescribed distance become substantially from 80 to 110 percent of an average value of said tensile stress after said heating source moves said prescribed distance.    
   
   
       14 . A method as claimed in  claim 12 , wherein said prescribed distance is substantially between 50 mm and 150 mm.  
   
   
       15 . A method as claimed in  12 , wherein said elongating speed is constant when said heating source moves said prescribed distance.  
   
   
       16 . A method as claimed in  claim 12 , wherein controlling elongating speed includes controlling a moving speed of a chuck, which holds said glass rod.  
   
   
       17 - 31 . (canceled)  
   
   
       32 . A method for manufacturing a perform, comprising: 
 setting a heating condition for heating a glass rod and an elongating speed of said glass rod;    heating and elongating said glass rod in a horizontal direction;    measuring tensile stress generated on said glass rod; and    controlling said heating and elongating said glass rod based on said measured tensile stress,    wherein said heating and elongating are controlled so that said tensile stress before said heating source moves a prescribed distance become substantially from 80 to 110 percent of an average value of said tensile stress after said heating source moves said prescribed distance.    
   
   
       33 . A method as claimed in  claim 51 , wherein said prescribed distance is substantially between 50 mm to 150 mm.  
   
   
       34 . A method as claimed in  claim 51 , wherein said elongating speed is constant when said heating source moves.  
   
   
       35 - 50 . (canceled)  
   
   
       51 . A method for manufacturing a perform, comprising: 
 setting a heating condition for heating a glass rod and an elongating speed of said glass rod;    heating and elongating said glass rod in a horizontal direction;    measuring tensile stress generated on said glass rod; and    controlling said heating and elongating said glass rod based on said measured tensile stress,    wherein said heating and elongating are controlled so that tensile stress before said heating source moves a prescribed distance becomes substantially 110 percent or below an average value of said tensile stress after said heating source moves said prescribed distance.