Method for manufacturing optical fiber preform and burner apparatus for this method for manufacturing optical fiber preform

Abstract

The present invention provides an optical fiber preform manufacturing method and a burner apparatus employed for this method. In this manufacturing method, when glass particles are synthesized in an oxy-hydrogen flame emitted from a burner to form a porous optical fiber preform by depositing glass particles in the radial direction of a starting member, the relationship between the flow rate vm (m/sec) of a source material gas or a mixed gas of the source material gas and an additive gas discharged from the burner, and the flow rate vs (m/sec) of an inert gas is such that −0.06 vm+1.4≦vs≦−0.02 vm+1.8, and vs≧0.40, while the relationship between the flow volume Vm (l/min) of the source material gas discharged from the burner and the flow volume Vs (l/min) of the inert gas is such that Vs/Vm≦0.2.

1 - 4 . (canceled)  
   
   
       5 . A burner apparatus for manufacturing optical fiber preform comprising: 
 a burner equipped with at least a first port that discharges a source material gas or a mixed gas of said source material gas and an additive gas provided on a central axis, and a second port that discharges an inert gas on the same central axis as said first port around said first port;    a gas supply source that supplies said source material gas, a flammable gas, a combustion supporting gas and said inert gas to said burner; and    a gas control unit that controls flow volume or flow rate of these gases.    
   
   
       6 . A burner apparatus for manufacturing optical fiber preform comprising: 
 a burner equipped with at least a first port that discharges a source material gas or a mixed gas of said source material gas and an additive gas provided on a central axis, and a second port that discharges an inert gas provided on the same central axis as said first port around said first port;    a gas supply source that supplies said source material gas, a flammable gas, a combustion supporting gas and said inert gas to said burner; and    a gas control unit that controls flow volume or flow rate of these gases.    
   
   
       7 . The burner apparatus of  claim 5 , adapted to accommodate sizes of gas flow paths that result from maintaining a relationship between a flow rate vm (m/sec) of said source material gas or said mixed gas of said source material gas and said additive gas discharged from said burner, and a flow rate vs (m/sec) of said inert gas, such that  
       −0.06 vm+1.4≦vs≦−0.02 vm+1.8, and vs≧0.40.  
   
   
       8 . The burner apparatus of  claim 6 , adapted to accommodate sizes of gas flow paths that result from maintaining a relationship between a flow volume Vm (l/min) of said source material gas and a flow volume Vs (l/min) of said inert gas, such that  
       Vs/Vm≦0.2.