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.

An optical fiber drawing furnace heating element includes a heat generator including: a tubular resistance heating element in which at least a part of an optical fiber preform is disposed in a through-hole; a first portion extending, from a first end portion, over a predetermined section along a longitudinal direction; and a second portion disposed closer to a second end portion than the first portion. The second portion has a wall thickness on a side of the first end portion being equal to or larger than a wall thickness of the first portion. The wall thickness of the second portion increases toward a side of the second end portion from the side of the first end portion.

A light diffusing optical fiber includes a core, a cladding surrounding the core, an outer surface, and a plurality of scattering structures positioned within the core, the cladding, or both the core and the cladding. The plurality of scattering structures are configured to scatter guided light towards the outer surface, such that light including a wavelength of from about 450 nm to about 650 nm diffusing through the outer surface along a diffusion length of the light diffusing optical fiber includes a spectral attenuation percent relative range of about 15% or less.

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.

Aspects of the embodiments include an optical fiber formed in a low gravity environment. The optical fiber can be used in airframe applications for missile defense, oil-field applications for down-well laser applications, optical communications, and other applications. The optical fiber can include a fluoride composition, such ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN), and can be characterized by an insertion loss in a range from 13 dB/1000 km to 120 dB/1000 km. The optical fiber can deliver optical energy with low insertion loss at the desired power and wavelength for the various applications.

An optical fiber manufacturing method includes setting a first holding member and a rod inside a glass pipe, the first holding member made of glass and having plural holes formed, so that the rod is supported by the first holding member; filling glass particles between the rod and a glass pipe inner wall; holding the rod such that the rod and the filled glass particles are enclosed by the glass pipe inner wall and the first and second holding members, and sealing one end of the glass pipe and manufacturing an intermediate; and manufacturing an optical fiber from the intermediate, wherein a bulk density of the first and second holding members is set with reference to a bulk density of a filling portion made from the glass particles, and the predetermined range is determined according to a core diameter permissible variation range in its longitudinal direction.

A system and method for nitridizing a glass article includes supplying a source of a nitridizing gas including gaseous NH.sub.3 to a glass article supported within a furnace assembly and heating the glass article. In some embodiments, the system includes a handle assembly configured to support the glass article within the furnace assembly and a gas supply conduit carried by the handle and configured to supply the nitridizing gas to the glass article. In some embodiments, a method of nitridizing a glass article includes supplying the nitridizing gas such that a residence time of the nitridizing gas at temperatures greater than 500 C. corresponds to a predetermined time period. In some embodiments, a method of nitridizing a glass article includes supplying the nitridizing gas such that the glass articles is exposed to the nitridizing gas within a contact time t.sub.c.

An optical fiber manufacturing method includes: melting and drawing an optical fiber preform to form a glass fiber; cooling the glass fiber while inserting the glass fiber into a tubular slow-cooling device from an inlet end toward an outlet end thereof; and lowering an inner wall temperature of the slow-cooling device below a temperature of the glass fiber and providing a pressure gradient in which a pressure increases in a direction from the inlet end toward the outlet end inside the slow-cooling device when cooling the glass fiber, wherein the average pressure change dP/dL in a moving direction of the glass fiber inside the slow-cooling device satisfies the following Formula (1) when the tube inner diameter of the slow-cooling device is defined as D [m] and the length of an internal space of the slow-cooling device in the moving direction of the glass fiber is defined as L [m].
(D.sup.2/4)dP/dL0.03(1)

A method for manufacturing an optical fiber includes: drawing an optical fiber from an optical fiber preform in a drawing furnace; and cooling the optical fiber in an annealing furnace. When the optical fiber enters the annealing furnace, a temperature difference between a temperature of the optical fiber and a fictive temperature of glass in a core of the optical fiber is 300 C. or less. The optical fiber is cooled for 0.01 seconds or more in the annealing furnace so that the temperature of the optical fiber becomes 1300 C. or more and 1800 C. or less.

A method for determining the temperature of a strand comprises disposing the strand along a background radiator of known temperature. Receiving the strand using a spatially resolving thermal imaging sensor in front of the background radiator while the strand is being disposed along its longitudinal axis. Forming an integral across a measuring value area, the integral configured to detect a complete strand portion located in front of the background radiator of the thermal imaging sensor. deducing the temperature of the strand by comparing the formed integral with a reference value.