Abstract: A sintering apparatus heat-treats a porous glass preform for an optical fiber at a high temperature. The sintering apparatus includes: a glass preform elevating/lowering mechanism; a furnace core tube having an upper part having an opening part into which the glass preform is inserted by the elevating/lowering mechanism, and made of quartz glass; a heating furnace disposed on an outer circumference of the furnace core tube; an upper lid for closing the opening part of the furnace core tube; and a sealing member holding mechanism included in the upper lid and configured to hold a sealing member interposed between the opening part and the upper lid.

Abstract: An electrical discharge, suitable for heating optical fibers for processing, is made in a controlled partial vacuum, such that saturation of available ionizable gas molecules is reached. The workpiece temperature is thereby made to be a stably controlled function of the absolute air pressure and is insensitive to other conditions. A system and method accomplishing the foregoing are provided.

Abstract: A method of manufacturing an optical fiber base material includes: forming a porous glass base material by depositing glass particles; providing a vessel which employs a composite tube, the composite tube including a portion formed by jacketing a first quartz glass containing aluminum equal to or less than 0.01 ppm with a second quartz glass containing aluminum equal to or more than 15 ppm; introducing dehydration reaction gas and inert gas into the vessel; heating the jacketed portion in the vessel which contains the dehydration reaction gas and the inert gas; and inserting the porous glass base material into the heated vessel to dehydrate and sinter the porous glass base material.

Abstract: A method of manufacturing a microstructured fiber, includes: providing a preform having a plurality of elongate holes; mating at least one, but not all, of the holes with a connector to connect the hole(s) to an external pressure-controller; drawing the preform into the fiber while controlling gas pressure in the hole(s) connected to the pressure-controller.

Abstract: A non-contact method for measuring the tension applied to a drawn optical fiber includes drawing an optical fiber and displacing the optical fiber by applying a pressurized fluid to the optical fiber. The pressurized fluid may be applied to the optical fiber using a fluid bearing. The fluid bearing may include a fiber support channel. The optical fiber may be directed through the fiber support channel and is displaced relative to the fluid bearing by supplying the pressurized fluid to the fiber support channel. The displacement of the optical fiber caused by the application of the pressurized fluid to the optical fiber may then be measured. The tension applied to the optical fiber may then be determined based on the determined displacement.

Abstract: A dehydration-sintering furnace for dehydrating and/or sintering an optical fiber preform for use in production of an optical fiber includes a muffle for accommodating the optical fiber preform, a heater for heating the muffle, and a pressure fluctuation absorbing apparatus connected to the muffle. Since the pressure fluctuation absorbing apparatus is thermally insulated from a room temperature atmosphere or heated, vapor produced in a dehydration-sintering process is prevented from condensing (liquefying) in a pressure fluctuation absorbing apparatus, thereby preventing reduced dehydration effectiveness in the muffle and reduced quality of the optical fiber preform.

Abstract: In a known method for producing tubes of quartz glass, a hollow cylinder (2) of quartz glass is continuously supplied to a heating zone (1) and is softened therein in regions, and a tube strand (21) is drawn off at a drawing speed from the softened region with formation of a drawing bulb (26), and the tubes to be produced are cut to length in the form of tube strand pieces by separating the tube strand (21) at a desired separation point (T, Vu, Vo) and an internal pressure differing from the external pressure applied to the outer cladding is maintained in the inner bore (4) of the hollow cylinder (2) in that the inner bore (4) of the tube strand is provided with a flow obstacle.

Abstract: A method is described for manufacturing an optical fiber preform, including a tube collapsing phase, and including monitoring the concentration of at least one fluid component of a fluid that is exhausted from the tube, to detect structural integrity of the tube. A system is also described for manufacturing optical fiber preforms. The system comprising a holder configured to hold a tube, a heater configured to heat at least part of the tube to a tube collapsing temperature, a fluid exhaust configured to discharge fluid from the tube, held by the holder. The system also includes a tube integrity monitor configured to monitor structural integrity of the tube, during a collapsing phase, by monitoring fluid that is discharged from the tube.

Abstract: A method for manufacturing an optical fiber preform is described that includes detecting structural integrity of the tube during a collapsing phase utilizing a fluid flow that is fed to the tube. Also, a system for manufacturing optical fiber preforms is described that comprises a holder configured to hold a tube, a heater configured to heat at least part of the tube to a tube collapsing temperature, and a fluid supply system configured to supply a fluid to the tube held by the holder. The system comprises a tube integrity monitor configured to monitor structural integrity of the tube, during a collapsing phase, by monitoring the fluid.

Abstract: A mold-press forming apparatus for applying a molding pressure to a mold containing a forming material to perform press forming includes a loading chamber (that is, an airtight chamber) P1 kept airtight. The loading chamber P1 is connected to a pressure reducing member which includes evacuating members 14 and 13 arranged in an evacuating path 7 connected to the loading chamber P1 for evacuating a gas in the loading chamber P1, and a plurality of valves 11 and 12 arranged in the evacuating path 7 in parallel to each other. When the loading chamber P1 is evacuated, the pressure reducing member changes a pressure reducing rate in the course of pressure reduction.

Abstract: A method of manufacturing an optical fiber base material includes: forming a porous glass base material by depositing glass particles; providing a vessel which employs a composite tube, the composite tube including a portion formed by jacketing a first quartz glass containing aluminum equal to or less than 0.01 ppm with a second quartz glass containing aluminum equal to or more than 15 ppm; introducing dehydration reaction gas and inert gas into the vessel; heating the jacketed portion in the vessel which contains the dehydration reaction gas and the inert gas; and inserting the porous glass base material into the heated vessel to dehydrate and sinter the porous glass base material.

Abstract: A method of manufacturing an optical fiber base material includes: forming a porous glass base material by depositing glass particles; providing a synthetic quartz glass vessel at least partly made of quartz glass which contains aluminum equal to or less than 0.01 ppm; introducing dehydration reaction gas and inert gas into the vessel; heating a portion made of quartz glass which contains aluminum equal to or less than 0.01 ppm in the vessel that contains the dehydration reaction gas and the inert gas; and inserting the porous glass base material into the heated vessel to dehydrate and sinter the porous glass base material.

Abstract: There is provided an apparatus and method for fabricating a holey optical fiber. An optical fiber with air holes of a predetermined size and shape along the length of the optical fiber is drawn by supplying nitrogen gas into air holes through one end of a holey optical fiber preform while heating the other end of the preform.

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: An inlet arrangement for inserting a preform (3?) into a furnace (1?) for drawing a fiber (2?). The furnace includes an enclosure (4?) at the top of which there are both an opening to allow insertion of a preform which moves in translation, and a preform inlet arrangement (13?). The inlet arrangement comprises both an injector (6?) situated at the level of the opening to inject inert gas around the preform and to fill the enclosure, and at least one seal (17B) fixed above the injector and designed to allow the preform to pass therethrough, with its cylindrical main body (9?) being surrounded. The inlet arrangement further comprises an airlock (13) for closing and sealing the top of the furnace, above the injector, whether a preform is present or absent, which airlock is pressurized to prevent the surrounding air entering. The rods of the equipped preforms carry respective continuity tubes (20) of the same diameter as the bodies.

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: This invention discloses a method and an apparatus for sintering a gel tube formed by a sol-gel change. The sintering apparatus comprises a reaction chamber for accommodating the gel tube, sealed under a vacuum condition; a vacuum pump for adjusting the degree of vacuum inside the reaction chamber according to a control signal; a vacuum gauge for measuring the degree of vacuum inside the reaction chamber; a movable part for supporting the gel tube and for rotating and vertically moving the gel tube according to the control signal; a temperature sensor for measuring the temperature inside the reaction chamber; a heater for adjusting the temperature inside the reaction chamber according to the control signal so as to sinter the gel tube; and, a controller for controlling the vacuum pump, the heater, and the movable part for sintering the gel tube under the vacuum condition.

Abstract: A method capable of stably drawing an optical fiber with a gas-seal system and an apparatus for implementing the method. The method produces an optical fiber 40b by drawing the optical fiber preform 30 by heating and softening the leading-end portion of it while feeding it into a drawing furnace 20. The drawing furnace 20 allows a gas 15 to blow against the optical fiber preform 30. The inside of the drawing furnace 20 is sealed with a seal ring 14U and a shutter 14L located at the top and bottom portions of it, respectively. While the gas 15 is fed, the inner diameter of the seal ring 14U is adjusted according to the diameter of the optical fiber preform 30. Consequently, even when the preform diameter varies, the clearance between the seal ring 14U and the optical fiber preform 30 can be maintained constant, thereby enabling a stable drawing operation.

Abstract: An apparatus for manufacturing a glass base material which is an parent material of an optical fiber, comprising: a tank which contains a raw material of the glass base material to vaporize the raw material to generate a raw material in gas phase; a temperature control unit which controls a temperature of the raw material; and a pressure control unit which controls the pressure of the raw material in gas phase.

Abstract: There is provided an apparatus and method for fabricating a holey optical fiber. An optical fiber with air holes of a predetermined size and shape along the length of the optical fiber is drawn by supplying nitrogen gas into air holes through one end of a holey optical fiber preform while heating the other end of the preform.

Abstract: A porous optical fiber preform dehydration and sintering apparatus capable of improving the sealing performance between an upper lid and an elevating shaft and between the upper lid and a furnace tube or a furnace body, wherein an upper opening of a furnace tube for accommodating a porous optical fiber preform is shut by the upper lid, a preform holder is provided at the bottom end of an elevating shaft passing through the upper lid to be freely elevated therethrough, the porous optical fiber preform in the furnace tube is heated by a heater provided around the outer circumference of the furnace tube, the upper lid is formed by a metal, the preform holder is formed by a quartz glass or a ceramic, a corrosion-resistant layer is provided on an inner surface of the upper lid, a seal member made of rubber or resin is provided in an elevating shaft passage of the upper lid.

Abstract: Disclosed is an apparatus for fabricating an optical fiber, which comprises a furnace for melting a sealed preform assembly to draw an uncoated optical fiber, a coater for coating the uncoated optical fiber, a capstan for drawing the optical fiber from the optical fiber preform by applying a drawing force, an adjoiner for holding a primary optical fiber preform inserted centrally into an overcladding tube with an equidistant space between the outer surface of the primary optical fiber preform and the inner surface of the overcladding tube, and a preform positioner for supporting the sealed preform assembly in a specified position with respect to the furnace.

Abstract: In a known method for the manufacture of a tube made of a vitreous material, especially of quartz glass, a hollow cylindrical semifinished product made of a vitreous material is carried essentially vertically to a heating zone, wherein it is heated and drawn off downwards—without the use of tools—to the tube by forming a transitional area from semifinished product to tube, while diameter and wall thickness of the tube are continuously measured, and the tube's measured geometrical data being used to generate a control signal with the aid of which a pressure difference is regulated between pressure P1 in the interior space of the semifinished product, the transitional area and the tube, as well as pressure P2 in the heating chamber which is regulated in the heating zone at least in the transitional area from semifinished product to tube and its adjacent tube area.

Abstract: A pressure monitoring system for use in monitoring gas pressure within a rotating tube has a chemical delivery tube which projects into the rotating tube and whose distal end is sealed to the interior wall of the tube. A coaxial tube surrounds the delivery tube and forms a passageway between the two tubes which is in communication with the rotating tube interior through the seal mounting means. The gas pressure within the passageway is an indication of the pressure within the rotating tube, and is measured within a pressure monitoring unit which can control the pressure through the gas supply or through a low pressure device. In a second embodiment of the invention, a buffer gas supply coupling member is mounted to the coaxial tube and sealed to the exterior of the rotating tube to create a buffer zone. In a third embodiment of the invention, the buffer zone arrangement is modified to produce a more complete flow of buffer gases within the buffer zone.

Abstract: A class preform (30) for making optical waveguides has surface impurities such as silicon carbide or silicon nitride. The preform is drawn in a furnace (12) that is supplied with oxygen via a conduit (40). The oxygen causes the impurities to oxidize and not effect the strength of the fiber.

Abstract: An optical waveguide substrate, which has less particles or concave pits caused by Oxidation Induced Stacking Fault on the quartz film when oxidizing the surface of the silicon substrate relatively thickly and forming on its surface a quartz film to become an optical waveguide, is manufactured. The making method of the optical waveguide substrate comprises a step of exposing a silicon substrate to an atmosphere of oxidizing gas while heating to form a quartz film on the surface thereof for an optical waveguide, characterized in that a density of Oxygen contained in said silicon substrate is 24 ppma at maximum.

Abstract: A silicon surface oxidation device utilizes a steam generator in which heated water is barely in contact with the members of the device, steam with no contamination is efficiently generated, and the silicon surface can be oxidized through relatively large thickness by using a steam oxidation method which is simple and high in safety. The steam generator has a feed port for pure water which flows along a surface in a chamber, an oscillator for oscillating a microwave toward the surface, a steam exit port for sending out the steam of the pure water generated from the surface by the microwave, and a discharge port for the pure water flowing along the surface. A heating furnace is connected to the steam exit port, and silicon placed in the heating furnace is oxidized by the steam generated by the microwave.

Abstract: An optical fiber drawing furnace capable of the prevention of entry of an ambient gas into an inner space thereof both effectively and economically, provided with a lower gas introduction portion through which inert gas is introduced into the inner space of the optical fiber drawing furnace, a chamber separated by a lower partition, and a bottom cover. The lower partition is arranged immediately below the lower gas introduction portion and has a first hole through which the chamber and the inner space are communicated. The bottom cover has a second hole through which the chamber and the atmosphere are communicated. An optical fiber is passed through the first and second holes. A controller detects a differential pressure between a pressure P1 in the inner space and a pressure P2 in the chamber and controls the suction flow by a pump for evacuating the gas in the chamber to maintain P1>P2.

Abstract: An optical fiber furnace having an access port for a preform is disclosed. The access port includes a gas pressure generation and sensing device and an automatic shutter door assembly. The gas pressure generation and sensing device responds to a sensed gas pressure built up around a new preform being inserted into the optical fiber furnace, for providing an automatic shutter door opening signal. The gas pressure generation and sensing device also responds to a sensed outwardly flowing purge gas pressure escaping around an exhausted preform being removed from the optical fiber furnace, for providing an automatic shutter door closing signal. The automatic shutter door assembly responds to the automatic shutter door opening signal, for opening the automatic shutter door assembly for inserting the new preform into the optical fiber furnace.

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: An apparatus is provided for applying a tensile force along the longitudinal axis of a cane assembly during the deposition of soot thereon to produce an optical fiber preform. Fiber drawn from such a preform exhibits improved core/clad concentricity. The tensile force may be applied at one or both ends of the cane assembly, with application at both ends being preferred. The tensile force may be varied during the deposition of soot. The cane assembly may be annealed prior to beginning the deposition of soot thereon.