A seal structure for an optical fiber drawing furnace is for plugging a gap between an upper end opening of the fiber furnace, and an optical fiber glass preform wherein a seed rod and a taper portion are present in an upper portion thereof. The seal structure comprises a first cap member engaging the seed rod of the glass preform; a second cap member covering the taper portion of the glass preform and the first cap member; a spacer member disposed between the first and second cap member, supporting the second cap member, adjusting, via a positional adjustment structure, the height position of the second cap member in the axial direction, and causing the lower extremity of the second cap member to be at a position close to the taper portion; and a seal member which seals between the upper end opening and the glass preform and/or second cap member.

A seal structure of an optical fiber drawing furnace for sealing a gap between an upper end opening of the optical fiber drawing furnace and an optical fiber glass preform inserted from the upper end opening, includes a plurality of blade members, a support mechanism for supporting the plurality of blade members, and a pressing operation mechanism for individually pressing the plurality of blade members in a radial direction of the optical fiber glass preform so as to bring distal ends of the plurality of blade members into contact with a side surface of the optical fiber glass preform, wherein a pressing force at the time of bringing the plurality of blade members into contact with the optical fiber glass preform is set at 0.1 to 10 N per blade member.

A furnace system includes a muffle defining a furnace cavity. A lower heater is coupled to the muffle and is configured to create a hot zone within the furnace cavity having a temperature of about 1900? C. or greater. An upper muffle extension is positioned above the muffle and defines a handle cavity. A downfeed handle is positioned within the handle cavity such that a gap is defined between an outer surface of the downfeed handle and an inner surface of the upper muffle extension. An upper heater is thermally coupled to the upper muffle extension and configured to heat the gap. A gas screen is positioned in the upper muffle extension and is configured to inject a process gas into the handle cavity.

An optical fiber preform manufacturing apparatus comprising a seal member, wherein the seal member is attached to a flange portion formed in an open portion of a reaction chamber into which a burner is inserted, the seal member includes a first sheet that is flexible and includes an open portion that is smaller than an outer diameter of the burner, through which the burner is inserted; a second sheet having the same thickness as the first sheet and including an open portion that is larger than an outer diameter of the first sheet; and two third sheets that each include an open portion that is larger than the outer diameter of the burner and smaller than the outer diameter of the first sheet, the second sheet is arranged in the same plane as the first sheet, and the first and second sheets are sandwiched by the two third sheets.

An optical fiber drawing method where a glass base material passes through an opening provided in a drawing furnace from the material side and drawing is performed by suspending and descending the material into the drawing furnace while being sealed by a sealing mechanism provided in the vicinity of the opening, in which a first portion of the sealing mechanism seals a gap between an outer peripheral surface of the material and an inner surface of the opening when drawing starts and a tapered portion of the material starts passing through the first portion, and a second portion is disposed above the first portion before sealing by the first portion becomes ineffective, and then conduction between inside and outside of the drawing furnace is carried out to prevent fluctuation of pressure inside the furnace immediately after disposing the second portion and the conduction is interrupted when the material further descends.

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 sensor system to provide data for use to control manufacture of an optical fiber in microgravity including a diameter sensor to monitor a diameter of a fiber drawn from a preform material, a tension sensor to monitor tension of the fiber as the fiber is pulled from the preform material to a storage device and a controller in communication with at least one of the diameter sensor and the tension sensor to evaluate sensor data to determine at least one of a speed and rate at which the fiber is pulled from the preform material.

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 system for receiving optical fiber in microgravity including a spool portion to hold optical fiber created in microgravity, a catching mechanism to secure the fiber end to the spool and a capturing device that is extendable from near and retractable to near the spool portion to pull the optical fiber to the spool portion.

A system for precoating a preform for drawing optical fiber including a diameter sensor to determine a diameter of pulled optical fiber, a cooling system to cool the optical fiber once it is pulled from a furnace, a coating system to apply a coating to the optical fiber once it has cooled and an ultra-violet lamp to cure the coating.