Process for vitrifying a porous soot body made of silicon dioxide used in the production of blanks for optical fibers comprises holding the soot body in a vertical position using a holding device, and continuously feeding to a heating zone

摘要

Process for vitrifying a porous soot body made of silicon dioxide comprises: (i) holding the soot body in a vertical position using a holding device; and (ii) continuously feeding to a heating zone (2a). The soot body is surrounded by a mold (4) from the entrance into the heating zone and is heated within the heating zone to a temperature at which it softens to the extent that on forming the vitrified soot body, the body adopts the lateral dimensions of the mold. The vitrified body is released from the mold. Preferred Features: The soot body longitudinally contracts during vitrification and the holding device is moved in the vertical direction with a controlled speed using a moving device (7) so that the soot body is fed to the heating zone corresponding to the heating zone. Vitrification is carried out in an argon, helium and/or nitrogen protective atmosphere.