A system for controlling an ambient microgravity environment of a system for drawing optical fiber including a filter arranged to cleanse an environment from contaminants, a molecular sieve arranged in a series of at least one of meshes and baffles to dehumidify the environment, at least one of a pump and a fan to draw an environmental gas through the filter, through the molecular sieve and back in to an ambient environment and a housing in which the filter, molecular sieve and at least one of pump and fan reside.

A preform material including a starter tip to facilitate an initial fiber draw from the preform within a furnace, wherein the tip comprises a vacuum-sealed tip to receive a plastic grip which attached to an end of a preform.

A gas branching apparatus that branches and supplies a gas to first to N-th supply targets, includes first to N-th pipes wherein the first to N-th pipes are each branched into first to N-th branch pipes on a downstream end side, and wherein the i-th branch pipes of the respective first to N-th pipes are connected in common to the i-th supply target, and the i-th branch pipes of the respective first to N-th pipes are provided with valves, respectively, where i denotes each of integers of 1 to N.

In a method for manufacturing an optical fiber, a dummy rod is connected to a vicinity of an upper end of a glass preform which includes a diameter-reduced portion at an upper portion thereof, and the glass preform is heated to be melt in a drawing furnace to draw an optical fiber. A cap member is provided at a position of the diameter-reduced portion, and an upper end of the cap member is disposed close to a lower end of the dummy rod. When an orthogonal coordinate axis is set, in which an outer diameter ratio of the cap member to the glass preform is set as a horizontal axis x, and an outer diameter ratio of the dummy rod to the glass preform is set as a vertical axis y, the x and the y satisfy an expression y0.1527x.sup.3.103.

A gas branching apparatus that branches and supplies a gas to first to N-th supply targets, includes first to N-th pipes wherein the first to N-th pipes are each branched into first to N-th branch pipes on a downstream end side, and wherein the i-th branch pipes of the respective first to N-th pipes are connected in common to the i-th supply target, and the i-th branch pipes of the respective first to N-th pipes are provided with valves, respectively, where i denotes each of integers of 1 to N.

A system for positioning an optical preform in a furnace is provided that includes an upper muffle and a downfeed handle assembly with a tube defining a first end and a second end, the second end extending into the upper muffle. A handle is disposed within the tube. A second end of the handle extends into the upper muffle and a seal assembly is positioned around both the tube and the handle. The first end of the handle extends through the seal assembly and a drive assembly is coupled with the downfeed handle.

There is provided a method for producing a multicore optical fiber while depressurizing holes in a common cladding tube. A production method for a multicore optical fiber includes a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an end-face working step of digging the common cladding tube from the second end to a predetermined depth to forming a third end, a connection step of connecting a glass tube to the second end, an insertion step of inserting core rods into the holes to the third end, a sealing step of sealing the first end, and a drawing step of spinning the multicore optical fiber while depressurizing the holes through the glass tube and combining the common cladding tube and the core rods from the first end.

A sealing arrangement for a drawing furnace including a vertical center hole with surrounding heating elements for receiving a glass preform including a tapered portion connected to an extension rod. A sealing with an opening is arranged on top of the furnace. The arrangement includes an outer annular bushing arranged on top of the furnace and an inner annular bushing with a first and an opposing second vertical end. The inner bushing is positionable to surround at least part of the tapered portion with the first end positioned to the region of the beginning of the tapered portion and the second end includes protrusions on the outer surface. As the inner bushing is inserted in the outer bushing it is arranged to be movable within the outer bushing and the protrusions form supports for holding the second end of the inner bushing above the center hole.

A system for drawing optical fiber in microgravity including a sealed housing to prevent infiltration of at least humidity and filled with a dry environment, a preform holder located within the sealed housing to hold preform material, a furnace located within the sealed housing to receive the preform material from the preform holder and to heat the preform material from which the optical fiber is pulled, a feed system to move the preform material from the preform holder to the furnace, a drawing mechanism located within the sealed housing to pull the optical fiber from the preform material within the furnace, a diameter monitor located within the sealed housing to measure a diameter of the optical fiber and a fiber collection mechanism located. within the sealed housing to gather and store the optical fiber.

A system for positioning an optical preform in a furnace is provided that includes an upper muffle and a downfeed handle assembly with a tube defining a first end and a second end, the second end extending into the upper muffle. A handle is disposed within the tube. A second end of the handle extends into the upper muffle and a seal assembly is positioned around both the tube and the handle. The first end of the handle extends through the seal assembly and a drive assembly is coupled with the downfeed handle.