Optical fiber draw furnace system and method

An optical fiber draw furnace system comprising:

• a muffle forming an inner cavity;
• a downfeed handle moveably disposed within the inner cavity and comprising an inner handle and an outer handle;
• a preform attachment member connected to the downfeed handle and configured to directly connect to an optical fiber preform;
• and
• a downfeed handle extension portion disposed radially outward of the preform attachment member, the downfeed handle extension portion being moveable with the outer handle and being moveable with respect to the preform attachment member from a first position, in which at least a bottom portion of the preform attachment member is exposed and not covered by the downfeed handle extension portion, to a second position, in which the bottom portion of the preform attachment member is radially covered by the downfeed handle extension portion.

An optical fiber draw furnace system comprising:

• a muffle forming an inner cavity;
• a downfeed handle moveably disposed within the inner cavity;
• and
• a preform attachment member connected to the downfeed handle and configured to connect to an optical fiber preform;
• and
• a downfeed handle extension portion connected to the downfeed handle and moveably disposed within the inner cavity,
• the downfeed handle extension portion being moveable with respect to the preform attachment member from a first position, in which at least a bottom portion of the preform attachment member is exposed and not covered by the downfeed handle extension portion, to a second position, in which the bottom portion of the preform attachment member is radially covered by the downfeed handle extension portion,
• a length of the downfeed handle extension portion being in a range from about 2 inches to about 25 inches, and
• the downfeed handle extension portion forming a first gap between an outer surface of the downfeed handle extension portion and an inner surface of the muffle, the first gap having a length in a range of about 0.001 m to about 0.2 m.