Dehydration-sintering furnace, a manufacturing method of an optical fiber preform utilizing the furnace and an optical fiber preform manufactured by the method

Abstract

A dehydration-sintering furnace for dehydrating and/or sintering an optical fiber preform for use in production of an optical fiber includes a muffle for accommodating the optical fiber preform, a heater for heating the muffle, and a pressure fluctuation absorbing apparatus connected to the muffle. Since the pressure fluctuation absorbing apparatus is thermally insulated from a room temperature atmosphere or heated, vapor produced in a dehydration-sintering process is prevented from condensing (liquefying) in a pressure fluctuation absorbing apparatus, thereby preventing reduced dehydration effectiveness in the muffle and reduced quality of the optical fiber preform.

1 . A manufacturing method of an optical fiber preform, comprising a step of utilizing said dehydration-sintering furnace comprising a muffle for dehydrating and/or sintering an optical fiber preform for use in production of an optical fiber, wherein a pressure fluctuation absorbing apparatus is connected to said muffle and said pressure fluctuation absorbing apparatus is covered with a thermally insulating material, wherein a gas temperature is 100 degrees Celsius or higher in said pressure fluctuation absorbing apparatus.  
   
   
       2 . A manufacturing method of an optical fiber preform, comprising a step of utilizing said dehydration-sintering furnace comprising a muffle for dehydrating and/or sintering an optical fiber preform for use in production of an optical fiber, wherein a pressure fluctuation absorbing apparatus is connected to said muffle and said pressure fluctuation absorbing apparatus is located in a thermally insulated container, wherein a gas temperature is 100 degrees Celsius or higher in said pressure fluctuation absorbing apparatus.  
   
   
       3 . A manufacturing method of an optical fiber preform, comprising a step of utilizing said dehydration-sintering furnace comprising a muffle for dehydrating and/or sintering an optical fiber preform for use in production of an optical fiber, wherein a pressure fluctuation absorbing apparatus is connected to said muffle and provided with heating means configured to heat said pressure fluctuation absorbing apparatus, wherein a gas temperature is 100 degrees Celsius or higher in said pressure fluctuation absorbing apparatus.  
   
   
       4 . A manufacturing method of an optical fiber preform, comprising a step of utilizing said dehydration-sintering furnace according to any one of claims  1 - 3 , wherein said gas temperature is 300 degrees Celsius or higher in said pressure fluctuation absorbing apparatus.  
   
   
       5 . A manufacturing method of an optical fiber preform according to any one of claims  1 - 3 , further comprising the steps of flowing of vapor that contains substances produced in the dehydration and/or sinter process to said pressure fluctuation absorbing apparatus, and preventing said vapor from condensing in said pressure fluctuation absorbing apparatus.