Process for producing synthetic quartz glas, jig for synthetic-quartz-glass production, and synthetic quartz glass for optical member

Abstract

An object of the invention is to provide a process for producing a synthetic quartz glass while taking account of a refractive index distribution remaining in the synthetic quartz glass; a jig for use in the synthetic-quartz-glass production process; and a synthetic quartz glass for an optical member, produced by the process. A process for producing a synthetic quartz glass, which comprises: depositing and growing fine quartz glass particles synthesized by flame hydrolysis of a glass-forming material on a rotating target to thereby form a porous quartz glass base of a substantially cylindrical shape; presintering the porous quartz glass base; and heating the presintered porous quartz glass base to a temperature not lower than the vitrification temperature to convert the base into a transparent glass, wherein in the step of conversion into a transparent glass, the porous quartz glass base is placed so as to make its growth axis vertical and a load is vertically imposed on the thus-placed porous quartz glass base.

1 . A jig for synthetic-quartz-glass production which is for use in the process of  claim 1  for vertically imposing a load on a porous quartz glass base, which jig comprises:
 a base table on which the porous quartz glass base is to be placed while keeping an axis of the porous quartz glass base vertical; 
 one or more guide members vertically disposed on the base table; and 
 a pushing member supported by the guide members so as to be freely movable in the vertical direction and to sandwich the porous quartz glass base between the pushing member and the base table, 
 wherein the pushing member vertically descends, while contacting the porous quartz glass base, accompanied with contraction of the porous quartz glass base heated to a temperature not lower than the vitrification temperature, to thereby vertically impose a load on the porous quartz glass base by the weight of the pushing member itself. 
 
     
     
         2 . The jig for synthetic-quartz-glass production of  claim 1 , which is made of carbon or SiC.