Optical fiber and a glass preform manufacturing method

An extrusion apparatus (100, 200) to manufacture a dried soot preform (130) characterized in that:

• a feed-hopper (104) adapted to feed silica slurry (102);
• a barrel (106) that is disposed beneath the feed-hopper (104) and adapted to receive the silica slurry (102), wherein the silica slurry (102) is pushed within the barrel (106);
• a die header (114) to extrude the silica slurry (102) such that the silica slurry (102) is cladded on a core rod (128) to form the soot preform (130),
• wherein the die header (114) comprises an iris frame (116);
• and the iris frame (116) further comprising:
• a plurality of vanes (302) such that each vane of the plurality of vanes (302) is adapted to move in a radial direction of the iris frame (116),
• wherein upon movement of each vane of the plurality of vanes (302), a central orifice (306) is created that exhibits a variable diameter, and
• wherein variation in the diameter of the central orifice (306) controls the diameter of the soot preform (130) to form a conical portion (134) at an end of the soot preform (130);
• and
• a drying furnace (118) that is disposed beneath the iris frame (116) and adapted to eliminate physisorbed moisture present in the soot preform (130) to produce a dried soot preform (132).