Abstract: An optical fiber manufacturing method includes: drawing an optical fiber preform to form a bare optical fiber; cooling the bare optical fiber by a non-contact direction changer; adjusting a temperature of the bare optical fiber in a temperature adjusting unit disposed downstream of the non-contact direction changer and upstream of a coating unit; disposing, in the coating unit, an uncured coating layer that comprises a resin precursor on an outer periphery of the bare optical fiber; and curing the uncured coating layer in a curing unit.

Abstract: The invention is directed to a method of preventing isopipe sag when using the overflow drawdown fusion process for making flat glass sheets. The method applies a vertical restraint on at least one end of an isopipe resting on a support to thereby reduce sage and/or the rate of sag during use of the isopipe. Using the vertical restraint block in accordance with the invention, the sag and/or rate of sag has been found to be reduced by at least 40 percent relative to an isopipe that does not use the vertical restraints of the invention or a compressive force along the sides of the isopipe.

Abstract: Methods and apparatuses for cooling optical fibers are disclosed. In one embodiment, In some embodiments, a cooling apparatus for cooling an optical fiber in a production process includes a channel defined by at least one sidewall assembly and a plurality of interior cavities positioned along the interior of the sidewall assembly. The interior cavities include at least one plenum, a first plurality of fluid supply cavities in fluid communication with the at least one plenum, and a second plurality of fluid supply cavities in fluid communication with the at least one plenum. Cooling fluid is supplied from the at least one plenum to the first plurality of fluid supply cavities in a first direction and the second plurality of fluid supply cavities in a second direction opposite the first direction.

Abstract: A method of making optical fibers that includes controlled cooling to produce fibers having a low concentration of non-bridging oxygen defects and low sensitivity to hydrogen. The method may include heating a fiber preform above its softening point, drawing a fiber from the heated preform and passing the fiber through two treatment stages. The fiber may enter the first treatment stage at a temperature between 1500° C. and 1700° C., may exit the first treatment stage at a temperature between 1200° C. and 1400° C., and may experience a cooling rate less than 5000° C./s in the first treatment stage. The fiber may enter the second treatment stage downstream from the first treatment stage at a temperature between 1200° C. and 1400° C., may exit the second treatment stage at a temperature between 1000° C. and 1150° C., and may experience a cooling rate between 5000° C./s and 12,000° C./s in the second treatment stage.

Abstract: Apparatus, systems and methods for monitoring and controlling the amount of moisture introduced into the forming hood area in the manufacture of mineral fiber insulation products. Moisture from coolant liquids, binder dispersions and binder diluents are all introduced deliberately into a forming hood; ambient moisture and water from combustion are additional sources. A series of global variable control valves, one for each fluid system; as well as individual variable control valves for each fiberizing unit are provided with associated meters. Sensors monitor fibrous pack conditions and ambient conditions and provide inputs to the valve control system. A specific 3-ring liquid dispensing system is also disclosed.

Abstract: Methods and apparatuses for cooling optical fibers are disclosed. In one embodiment, In some embodiments, a cooling apparatus for cooling an optical fiber in a production process includes a channel defined by at least one sidewall assembly and a plurality of interior cavities positioned along the interior of the sidewall assembly. The interior cavities include at least one plenum, a first plurality of fluid supply cavities in fluid communication with the at least one plenum, and a second plurality of fluid supply cavities in fluid communication with the at least one plenum. Cooling fluid is supplied from the at least one plenum to the first plurality of fluid supply cavities in a first direction and the second plurality of fluid supply cavities in a second direction opposite the first direction.

Abstract: In an optical fiber manufacturing method, the cooling device and the coating device are connected in an airtight manner and by preventing a cooling gas, flowing inside the cooling device, from flowing into the coating device by a meniscus of resin inside of the coating device, a flow of the cooling gas inside the cooling device is discharged to an outside of an upper end of the cooling device as an upward stream; helium gas as the cooling gas flows into a lower portion of the cooling device and carbon dioxide gas as the cooling gas which is separated from the helium gas flows into a side lower than a position where the helium gas flows in, during the forcible cooling; and a flow rate of the helium gas and a flow rate of the carbon dioxide gas are individually controlled.

Abstract: In one embodiment, an optical fiber cooling system includes a first cooling tube oriented substantially in parallel with and spaced apart from a second cooling tube such that an optical fiber pathway is positioned between the first cooling tube and the second cooling tube. The first cooling tube includes a plurality of cooling fluid outlets positioned along an axial length of the first cooling tube which are oriented to direct a flow of cooling fluid across the optical fiber pathway towards the second cooling tube. The second cooling tube includes a plurality of cooling fluid outlets positioned along an axial length of the second cooling tube which are oriented to direct a flow of cooling fluid across the optical fiber pathway towards the first cooling tube.

Abstract: A method for forming an optical fiber includes drawing the optical fiber from a glass supply and treating the fiber by maintaining the optical fiber in a treatment zone wherein the fiber is cooled at a specified cooling rate. The optical fiber treatment reduces the tendency of the optical fiber to increase in attenuation due to Rayleigh scattering, and/or over time following formation of the optical fiber due to heat aging. Methods for producing optical fibers along nonlinear paths incorporating fluid bearings are also provided thereby allowing for increased vertical space for the fiber treatment zone.

Abstract: An optical fiber production system and method are provided for producing optical fiber. An optical fiber is drawn from a preform in a furnace and passes through a treatment device under a reduced pressure in the range of 0.01 to 0.80 atm. The treatment device cools the bare optical fiber as it cools to a temperature in the range of at least 1,600° C. to 1,300° C. A non-contact fiber centering device is located near an exit of the treatment device to provide centering of the optical fiber as it exits the treatment device.

Abstract: A method of manufacturing a single mode optical fiber formed of a silica-based glass and including a glass part having a central core and a cladding region. The method including heating an optical fiber preform in a heating furnace including a first heater to melt the optical fiber preform, and fiber drawing an optical fiber from the molten optical fiber preform. The method further comprises continuously cooling the drawn optical fiber starting with a meniscus portion in which diameter is decreased from 90% of the preform diameter to 5% of the preform diameter to a portion where the drawn optical fiber has a temperature of 1,200° C. at a cooling rate of 1,000 to 3,000° C. /sec.

Abstract: An apparatus for adjusting the cooling members located beneath fiberizing bushings is disclosed having the capability of moving each cooling member, or one portion of each cooling member, in a generally vertical direction, and/or in a lateral and/or tilting direction. Also disclosed is a process of using the apparatus to make fibers from molten material including molten glass.

Abstract: An induction furnace capable of drawing large diameter preforms of up to 130 mm is described. The induction furnace has top and bottom chimneys surrounding the entire preform during operation of the furnace with an inert conditioning gas which is introduced into the top chimney and flows downward through the furnace body and bottom chimney without significant turbulence. A distributor ring inside the top chimney redirects flow from a circumferential direction to a downward direction. The top chimney also includes a resilient seal to releasably hold the top of the preform. The bottom chimney has a smoothly decreasing cross-sectional area preventing turbulence at the furnace exit. The furnace insulation is preferably a rigid self-supporting graphite cylinder. A method of drawing large diameter preforms either to an optical fiber or to a preform of smaller diameter using such a furnace is also described.

Abstract: A method for manufacturing an optical fiber by drawing an optical fiber preform softened by heating, includes cooling the optical fiber at a cooling rate of not more than 4000° C. per second at a temperature of 1200 to 1400° C. of the optical fiber; and cooling the optical fiber at a cooling rate of not more than 8000° C. per second at a temperature of 850 to 1200° C. of the optical fiber. A drawing rate of the optical fiber is not less than 1000 meters per minute.

Abstract: An apparatus and method for recovering and recycling a coolant gas from a heat exchanger. The apparatus comprises a coolant gas recovery section, and analysis section, and a coolant gas blending section. The coolant gas recovery section recovers a coolant gas containing contaminants from the heat exchanger. The analysis section monitors a condition of an analysis portion of the recovered coolant gas. The coolant gas blending section operates to produce, based on the condition of the recovered coolant gas monitored by the analysis section, a blend coolant gas comprising a virgin coolant gas and a reclaimed coolant gas that comprises at least a portion of the recovered coolant gas. The blend coolant gas has a predetermined contaminant concentration and is recycled into the heat exchanger. Thus, the coolant gas is recovered from, and recycled to, the heat exchanger at the predetermined contaminant concentration without using a purification device.

Abstract: A cap assembly for collecting cooling gas from a coolant chamber tube is disclosed. The cap assembly having connecting means and outlet means extending from its side walls being generally shaped and sized for detachable mounting on the body of the cooling gas chamber tube. The cap assembly is also employed in a hot optical fiber process which is being cooled by helium.

Abstract: The method of manufacturing an optical fiber in accordance with the present invention comprises a step of yielding an optical fiber by drawing an optical fiber preform softened upon heating, wherein a temperature at which the optical fiber preform is softened is at least 1800° C., whereas the optical fiber preform or optical fiber has a glass cooling rate of 4000° C./sec or less when attaining a temperature of 1800° C.

Abstract: An apparatus and method for curing a coating applied to an optical fiber. A water-jacketed UV lamp is provided adjacent a first reflector. An optical fiber is drawn between a second reflector opposite the first reflector and at least one quartz plate, while a cross flow of a cooling gas is passed around the optical fiber. Apertures may be formed in the second reflector for passing the cooling gas while the optical fiber is passed between the second reflector and the at least one quartz plate. Alternatively, two or more quartz plates may be provided and the cooling gas and the optical fiber passed between the quartz plates. The cooling gas experiences laminar flow.

Abstract: A cap assembly for collecting cooling gas from a coolant chamber tube is disclosed. The cap assembly having connecting means and outlet means extending from its side walls being generally shaped and sized for detachable mounting on the body of the cooling gas chamber tube. The cap assembly is also employed in a hot optical fiber process which is being cooled by helium.

Abstract: A cap assembly for collecting cooling gas from a coolant chamber tube is disclosed. The cap assembly having connecting means and outlet means extending from its side walls being generally shaped and sized for detachable mounting on the body of the cooling gas chamber tube. The cap assembly is also employed in a hot optical fiber process which is being cooled by helium.

Abstract: The present invention relates to a method and apparatus for cooling an optical fiber during the drawing process of said fiber. In particular the present method for cooling an optical fiber comprises flowing a cooling gas onto the optical fiber wherein the flow direction of the cooling gas is substantially transversal with respect the longitudinal axis of the fiber. It has been found that by employing a flow of cooling gas being substantially transversal to the longitudinal axis of the drawn fiber, the cooling efficiency of the fiber may be substantially improved.

Abstract: Disclosed is a cooling apparatus used in a high-speed cooling of an optical fiber. The cooling apparatus includes: a cooling body extending along the longitudinal direction of the drawn optical fiber, wherein the cooling body consists of a left cooling body part and a right cooling body part, and wherein the cooling body is provided with a sealing cap so that a cooling gas is supplied into the cooling body through the sealing cap; and, at least one turbulence generator mounted within the cooling body to surround the drawn optical fiber, wherein the turbulence generator activates the molecular flow of the cooling gas supplied into the cooling body.

Abstract: This invention is directed to a process for recovering helium. The process includes a) passing a first gas containing helium to an eductor to produce a second gas; b) passing the second gas through a heat exchanger to produce a third gas; and c) recovering the third gas into the eductor to combine with the first gas.

Abstract: An end heating and processing method of an optical fiber preform. In this method, an optical fiber preform is processed by heating and melting an end of a vitrified optical fiber preform including a core portion and a cladding portion formed on an outer circumference thereof to process the end having a shape for drawing as an optical fiber.

Abstract: In a single mode optical fiber formed of a silica-based glass and including a glass part having a central core and a cladding region, the density of non bridging oxygen hole center in the glass part is not higher than 1.0×1014 spins/g in terms of the spin density measured by an electron spin resonance method.

Abstract: Disclosed herein is a dual-type system for producing optical fibers. According to this system, a draw tower is partitioned into a first spinning chamber and a second spinning chamber by a central partition frame. A preform feed unit, a furnace, a spinning nozzle and a diameter gauge are installed on each of the first and second spinning chambers in order to spin an optical fiber. Two coating units are installed at the lowest unit of the draw tower at positions corresponding to the first and second spinning chambers and used for coating the surfaces of the optical fibers spun and drawn through the first and second spinning chambers. Two ducts each having a filter are installed on a side of each unit of the draw tower at positions corresponding to the first and second spinning chambers for supplying fresh air to the optical fibers so as to prevent the optical fibers from absorbing foreign substances in addition to cooling the optical fibers.

Abstract: A method and device for reducing the temperature of an optical fiber wherein a housing body is provided a plurality of inner cooling chambers which are-, partitioned from each other by a plurality of partition walls. An axial through hole extends through each of the inner cooling chambers from an upper end of the housing body to a lower end of the housing body for the axial passage of an optical fiber therethough. A plurality of gas injection holes corresponding to the inner cooling chambers are provided in a side wall of the housing body for injecting gas into the inner cooling chambers. A plurality of coolant pipes through which a liquid coolant is circulated extend through each of the inner cooling chambers from the upper end to the lower end of the housing body. The coolant pipes are disposed between the gas injection holes and the axial through hole so that the gas which is injected into the inner cooling chambers via the gas injection holes is not blown directly against the fiber.

Abstract: The invention relates to a device for drawing optical fibers from a preform, comprising: a furnace comprising a tube for heating one end of said preform to the drawing temperature thereof, which tube comprises: i) a central tube, ii) an upper extension tube connected to the lower part of said central tube so as to obtain a gas tight seal against an ambient atmosphere exterior said furnace, wherein the upper extension tube comprises an inlet for an inert gas in the top region of the upper extension tube, as a result of which the preform and the fiber to be drawn therefrom are surrounded by an inert gas, iii) a lower extension tube connected to said upper extension tube in such a manner that a gas tight seal against an ambient atmosphere exterior said furnace is obtained, iv) a tube outlet connected to said lower extension tube, means for drawing the fiber, means for supporting the preform in the furnace.

Abstract: Disclosed is a system for drawing an optical fiber for controlling polarization mode dispersion. A furnace is provided for uniformly heating an optical fiber preform in the drawing system mounted to an optical fiber draw tower. The furnace comprises: (a) a main body; (b) a sub-body placed coaxially with the main body and having a diameter smaller than that of the main body; and (c) an upper gas feeding section over the main body, wherein the upper gas feeding section includes a first hollow rotary body having at least one slit in the inner surface thereof along the longitudinal direction of an optical fiber and at least one opening extended in the direction of the center, whereby a gas artificially/periodically creates non-contact polarization to the optical fiber by the first hollow rotary body. Effective non-contact control can be carried out about polarization mode dispersion of the optical fiber.

Abstract: An apparatus and method for curing a coating applied to an optical fiber. A water-jacketed UV lamp is provided adjacent a first reflector. An optical fiber is drawn between a second reflector opposite the first reflector and at least one quartz plate, while a cross flow of a cooling gas is passed around the optical fiber. Apertures may be formed in the second reflector for passing the cooling gas while the optical fiber is passed between the second reflector and the at least one quartz plate. Alternatively, two or more quartz plates may be provided and the cooling gas and the optical fiber passed between the quartz plates. The cooling gas experiences laminar flow.

Abstract: An apparatus and process for cooling a quartz tube used in fabrication of an optical fiber preform by modified chemical vapor deposition. The apparatus has a nozzle ring supplied with a coolant. The nozzle ring has at least two vent sections that are be separatable for detaching the quartz tube from a lathe during processing, and a plurality of vents formed along the inside of the two vent sections for ejecting the coolant.

Abstract: In a known process for the manufacture of an elongated porous SiO2 preform, SiO2 particles are deposited on the mantle surface of a cylindrical carrier rotating about its longitudinal axis. The SiO2 particles are formed by means of a plurality of deposition burners which are arranged, at a distance from one another, in at least one burner row extending parallel to the longitudinal axis of the carrier. The burners are moved in a repeated cycle back and forth along the forming preform and between turnaround points where the direction of their motion is reversed. Measures are taken in the process to prevent or reduce overheating of the preform in the turnaround point regions. These measures can lead to variations in the rate of deposition.

Abstract: An apparatus and method for manufacturing an optical fiber preform from a tube of vitreous material. A holding device holds the tube during manufacture of the preform and a heater supplies the necessary heat energy for preform manufacturing. A diffuser is disposed adjacently to an end of the tube of vitreous material to trap and diffuse light radiation generated in the tube by the heater. The invention can be used in an apparatus for drawing an optical fiber from a preform. The diffuser traps and diffuses light radiation generated in the optical fiber preform by a fiber drawing oven.

Abstract: A cooler of an optical fiber draw tower, situated below a melting furnace for melting a preform for an optical fiber, for cooling the optical fiber drawn from the preform melted in the melting furnace, includes at least one heat exchanger installed with a predetermined length surrounding the optical fiber drawn from the melting furnace, for cooling the drawn optical fiber. The heat exchanger is formed of a thermoelectric cooler (TEC) for taking electrical energy through one heat absorbing surface to emit heat to the other heat emitting surface and has a tubular shape in which the heat absorbing surface of the TEC surrounds the optical fiber drawn from the melting furnace along the drawing direction by a predetermined length, and the drawn optical fiber is cooled as it passes through the tubular TEC. Also, the cooler further includes an auxiliary cooler attached to the heat emitting surface of the TEC, for cooling the emitted heat.

Abstract: The disclosed invention is a rotationally symmetrical resistance furnace heating element. The heating element has at least two ends. A respective cooling element is disposed in communication with each end. The heating element includes at least first and second high current density sections. The high current density sections are axially separated by at least one low current density section. The high current density sections have a smaller diameter than the low current density section. The invention also includes a multiple crucible method of drawing an optical fiber from the draw furnace described above. The method includes the step of heating an entire body of raw materials in a hot zone in the furnace.

Abstract: Helium recycling for optical fiber manufacturing in which consolidation process helium is recycled either directly for use in consolidation at high purity or recycled at lower purity adequate for usage in draw or other processes having a lower helium parity. Integrated processes for recycling helium from two or more helium using processes in the optical manufacturing process are also described. Substantial helium and cost savings are recognized.

Abstract: An apparatus for forming a optical fiber which includes a furnace for softening an optical fiber blank; a tractor for drawing the optical fiber from the softened optical fiber blank; and a first applicator for applying a coating of a first coating material to the optical fiber, the first applicator having a rotatable die.

Abstract: Hot optical fiber being drawn from a preform is cooled in a helium cooled heat exchanger by a two-stage process. In the first stage, in which the rate of draw of fiber through the heat exchanger is increased to the design draw rate, the rate of flow of helium to the heat exchanger is increased as the rate of draw of fiber is increased. Helium is withdrawn from the heat exchanger by a variable speed blower, and during the first stage the rate of withdrawal of helium from the heat exchanger is controlled primarily by the rate of flow of helium into the heat exchanger, and during the second stage, the rate of flow of helium to the heat exchanger is maintained constant and the rate of withdrawal is determined primarily by the pressure in the heat exchanger.

Abstract: The transmission properties of an optical fiber are enhanced by cooling the fiber gradually to temperatures of at least -300.degree. Fahrenheit, maintaining the fiber at such reduced temperature for a time suitable to stabilize the transmission properties of the fiber, and then allowing the fiber gradually to return to normal room temperature. The heating of the fiber to restore it to room temperature in part is accomplished by transmitting through the fiber optical pulses of the frequency and repetition rate the fiber will experience in normal use.

Abstract: A heat-absorbing finshield assembly, which is located adjacent the discharge area of a furnace for producing glass fibers, includes fins spaced along a fluid-cooled manifold such that the fins extend between, but not in contact with, the molten glass fibers emerging from the furnace. The fins may have microfins in their bases which are in contact with the cooling fluid. The fins also may be of variable thicknesses relative to each other along the manifold to absorb different quantities of heat from the emerging fibers.

Abstract: The present invention furnishes a method for producing mineral wool wherein a molten mineral material is fed into a spinner (1) the peripheral wall (2) of which comprises a multiplicity of orifices with small diameters wherethrough the mineral molten material is centrifuged to form filaments which are subjected to a supplementary attenuating effect of a gas flow flowing along and heating the peripheral wall (2) of the spinner (1) and generated by a concentric annular burner (8) arranged concentrically to the spinner (1), and wherein the exit area of the burner (8) is subdivided into an annular radially inner hot zone and an annular radially outer cooling zone of substantially lower temperature; the invention moreover concerns an apparatus for implementing the method.

Abstract: A coated optical fiber is produced by the steps of cooling through a cooling assembly an optical fiber obtained by drawing, heating and spinning an optical fiber base material and thereafter coating the optical fiber with a resin wherein a gas mixture including an He gas and possible ambient air is sucked out of the cooling assembly and purified to collect the He gas to be a recovery gas of He which is to be recycled to the cooling assembly together with a pure He gas, but the gas mixture sucked out of the cooling assembly is compressed and stored until the gas mixture reaches a predetermined pressure or more and then purified when it reaches the predetermined pressure while the compressed gas mixture is returned to an upstream side of a compressor which serves to compress the gas mixture so that the flow quantity of gas suction varies in accordance with the flow of He gas supplied to the cooling assembly whereby the gas mixture from the cooling assembly is prevented from lowering an He gas concentration of t

Abstract: To draw an optical fiber (10) from one end of a glass preform (9) which is heated to above the glass softening temperature at least in that area, a gas (21) flows around the preform (9) into a furnace space (16) during the drawing process and subsequent feeding of the preform. During the feeding, the areas that are adjacent to the drawing end of the preform (9) pass through gas zones in which the helium content of the furnace gas increases in the drawing direction.

Abstract: In a method of making fibers in which molten glass is extruded through orifices in a bushing and cooled with cooling apparatus mounted below the bushing to form the fibers, it has been discovered that using new alloys containing a major amount of palladium and a minor amount of either iridium or nickel to make the cooling members or apparatus offers many advantages. Using semi-automatic welding to attach separate parts of the cooling members or apparatus minimizes porosity in the weld and increases service life.

Abstract: A furnace and method for drawing an optical fiber is provided. The furnace included a furnace core chamber in which a preform is inserted into the chamber through the upper end thereof and a drawn optical fiber is pulled out of the chamber through an opening positioned at the lower end thereof. The furnace also includes a gas-supply means for introducing an inert gas into the furnace core chamber to thus establish an inert gas atmosphere within the chamber, and a heater for heating the preform so that the lower part of the preform is molten and drawn into the optical fiber, which is positioned around the outer periphery of the furnace core chamber. The furnace further includes an inner furnace core tube, which is positioned within the furnace core chamber and which has a cylindrical part whose lower part is communicated to the opening of the furnace core chamber and a funnel-like part which is positioned on the upper end of the cylindrical part.

Abstract: A system and process for recovering high purity coolant gas from at least one fiber optic heat exchanger, characterized by controlling a flow of coolant gas into and out of the heat exchanger using a pressure, impurity and/or flow rate monitoring or transmitting means in conjunction with a flow adjusting or controlling device to limit air or other gas infiltration into at least one fiber optic passageway of the heat exchanger. A sealing means may also be used at at least one end of the fiber optic passageway to further reduce air or other gas infiltration into the passageway. The resulting high purity coolant gas from the outlet of the heat exchanger is delivered to the inlet of the heat exchanger. Optionally, the resulting coolant gas from the outlet of the heat exchanger may be cooled, filtered and/or purified before being delivered to the inlet of the heat exchanger.

Abstract: A system and process for recovering high purity coolant gas from at least one fiber optic heat exchanger, characterized by controlling a flow of coolant gas into and out of the heat exchanger using a pressure, impurity and/or flow rate monitoring or transmitting means in conjunction with a flow adjusting or controlling device to limit air or other gas infiltration into at least one fiber optic passageway of the heat exchanger. A sealing means may also be used at at least one end of the fiber optic passageway to further reduce air or other gas infiltration into the passageway. The resulting high purity coolant gas from the outlet of the heat exchanger is delivered to the inlet of the heat exchanger. Optionally, the resulting coolant gas from the outlet of the heat exchanger may be cooled, filtered and/or purified before being delivered to the inlet of heat exchanger.

Abstract: The invention concerns the method and apparatus to fabricate an oval cross-sectional optical waveguide which only allows light to propagate in one direction of polarization. The optical waveguide preform for such an optical waveguide according to the modified chemical vapor deposition (MCVD) process is produced in such a way, that cooling is used to provide the substrate tube with an oval or elliptical temperature cooling profile. The apparatus for carrying out the fabrication method includes a cooling device (5) mounted to a support (3) beside a gas burner (4) and consists of two nozzles (10) directed toward the substrate tube (2) so as to direct cooling gas toward the substrate tube as glass layers are deposited thereon to produce core and cladding of the optical waveguide. The nozzles rotate synchronously with the substrate tube.

Abstract: A reactor for applying a carbon coating to an optical waveguide fiber wherein the buildup of reaction by-products within the reactor is reduced by providing internal and external fiber exit ports with the diameter of the internal fiber exit port being greater than the diameter of the external fiber exit port, and gas shielding at the external fiber exit port.

Abstract: A mass production method and apparatus of hermetic coating optical fiber where a bare fiber drawn from a preform is hermetically coated by CVD method in a reactor vessel, wherein a liquid flushes solid particles or by-products sticking to the reactor inner wall. The liquid may be supplied continuously or intermittently, to flush carbon particles generated during carbon coating process. The invention enables to produce a long hermetic coating optical fiber without choking the reactor, and improves a yield rate and productivity.