Abstract: An optical fiber heat exchanger includes an outer body and an inner body inserted into the outer body. The inner body includes a plurality of guide walls to guide a cooling liquid through the optical fiber heat exchanger to exchange heat from an optical fiber inserted in the optical fiber heat exchanger, a first set of parallel straight channels, extending along an inlet portion of the inner body, formed by a first subset of the plurality of guide walls, a set of U-shaped channels, extending through a transition section of the inner body, formed by a second subset of the plurality of guide walls, and a second set of parallel straight channels, extending along an outlet portion of the inner body, formed by a third subset of the plurality of guide walls.

Abstract: An optical fiber manufacturing apparatus includes: a cylindrical shield pipe that is provided above a drawing furnace, and forms a space continuous with the heating space in a vertical direction; a sending rod that has a lower end attached to an optical fiber preform and a lower portion disposed inside the shield pipe, and is configured to insert the optical fiber preform into a heating space of the drawing furnace in the vertical direction; an alignment mechanism that is configured to move the sending rod in a horizontal direction; an inner sealing body that is attached to the lower portion of the sending rod; and an outer sealing body that is mounted on the inner sealing body, is configured to move in the horizontal direction with respect to the inner sealing body, and is spaced apart from the sending rod.

Abstract: In order to prevent thermal deformation of a thermal insulating board and scattering of radiant heat when sintering porous glass base material, provided is a thermal insulating member is arranged on a dummy rod above a porous glass base material, which is formed by depositing glass fine particles on the outside of a starting member formed by connecting the dummy rod to at least one end of a core rod, when heating the porous glass base material to achieve sintering. The thermal insulating member comprises a cylindrical insulating cylinder; an insulating upper board connected to a top end of the insulating cylinder; an insulating lower board connected to a bottom end of the insulating cylinder; and a thermal deformation preventing member that prevents thermal deformation of at least one of the insulating cylinder, the insulating upper board, and the insulating lower board.

Abstract: A heating apparatus of an induction furnace used for stretching large-diameter preformed rods of optical fibers, said heating apparatus of the induction furnace comprising a furnace casing, a graphite exothermic sleeve, an insulating layer and an induction coil. At the upper end of the graphite exothermic sleeve is provided a floating seal gland, the inner bore thereof being adapted to the upper end of the graphite exothermic sleeve, and the outer periphery of the floating seal gland being adapted to the top cover plate furnace hole of the furnace casing. The use of the floating seal gland increases furnace stability and prolongs furnace life.

Abstract: An apparatus for mixing a vaporized precursor with a gas for producing silica particles is provided. The apparatus includes a mixer housing, a precursor delivery chamber having an output in communication with the mixer housing for delivering a vaporized precursor in the mixer housing, and an oxidizing gas delivery chamber having an output in communication with the mixer housing for delivering an oxidizing gas to be mixed with the vaporized precursor. The apparatus further includes a flashback member disposed within the mixer housing and between the output of the precursor delivery chamber and the output of the oxidizing gas delivery chamber. The flashback member is located at a minimum distance from the output of the oxidizing gas delivery chamber defined by Lminimum (cm)=0.453 U (Re)?0.5567, wherein U is the flow rate in cm/sec of precursor and Re is the flow Reynolds number. The flashback member may include a tapered surface on at least one side to reduce recirculation of vaporized gas.

Abstract: An apparatus includes a susceptor and a protective pipe. A gas containing 50% or more of argon or nitrogen is used as a gas to be supplied into the susceptor. The protective pipe has a heat insulating region (17a) enclosed with a heat insulator (18) with a length of Db (mm) at the upper section thereof and a non-heat insulating region (17b) not enclosed with any heat insulators at the lower section thereof. The temperature of the glass fiber at the outlet of the protective pipe becomes 1700° C. or less. The outer diameter of the glass fiber at the outlet of the protective pipe is within a range of the target outer diameter of the glass fiber+6 ?m or less.

Abstract: In order to provide a glass base material elongating apparatus that can safely elongate a glass base material in an extendable top chamber without damaging a flange, provided is a glass base material elongating apparatus comprising a heating furnace; an extendable top chamber formed of a multilayer cylinder disposed above the heating furnace; a glass base material hanging mechanism that hangs a glass base material into the heating furnace and the extendable top chamber; and a top chamber lifting mechanism. A flange is formed on a top portion of an outermost tube of the multilayer cylinder, and the top chamber lifting mechanism includes a cylinder support member that supports the flange from below and a cylinder lifting member that lifts up the cylinder support member.

Abstract: A heating apparatus of an induction furnace used for stretching large-diameter preformed rods of optical fibers, said heating apparatus of the induction furnace comprising a furnace casing, a graphite exothermic sleeve, an insulating layer and an induction coil. At the upper end of the graphite exothermic sleeve is provided a floating seal gland, the inner bore thereof being adapted to the upper end of the graphite exothermic sleeve, and the outer periphery of the floating seal gland being adapted to the top cover plate furnace hole of the furnace casing. The use of the floating seal gland increases furnace stability and prolongs furnace life.

Abstract: A method of processing an optical fiber includes introducing fiber that has passed a pulling mechanism to a shredding unit with an introducing unit. The introducing unit includes a movable unit including a notch configured to fit with a capstan roller included in the pulling mechanism, a sliding mechanism that attaches the movable unit slidably with respect to a main body of the introducing unit, and a restoring mechanism configured to restore the movable unit to an initial position when the movable unit has slid. The method includes shredding the fiber introduced by the introducing unit into fiber pieces, and suctioning, carrying, and collecting the fiber pieces. A method of drawing an optical fiber includes drawing the fiber while controlling a drawing speed, adjusting a diameter of the fiber to a diameter passable through a die, and arranging the die around the fiber having the diameter passable through the die.

Abstract: An optical fiber manufacturing apparatus including: a heating furnace in which an optical fiber is formed by melt-drawing an optical fiber preform; a sealing mechanism which is provided on an opening portion located at an upstream of the heating furnace and seals the heating furnace with an inert gas; a first pipe which is connected to the heating furnace and introduces the gas into the heating furnace; a second pipe which is connected to a lowermost compartment closest to the heating furnace among the compartments and introduces the gas into the lowermost compartment; and a gas flow rate control unit which controls a total sum of a flow rate of a gas supplied from the first pipe into the heating furnace and a flow rate of a gas supplied from the second pipe into the lowermost compartment to be substantially constant.

Abstract: An optical fiber manufacturing apparatus including: a heating furnace in which an optical fiber is formed by melt-drawing an optical fiber preform; a sealing mechanism which is provided on an opening portion located at an upstream of the heating furnace and seals the heating furnace with an inert gas; a first pipe which is connected to the heating furnace and introduces the gas into the heating furnace; a second pipe which is connected to a lowermost compartment closest to the heating furnace among the compartments and introduces the gas into the lowermost compartment; and a gas flow rate control unit which controls a total sum of a flow rate of a gas supplied from the first pipe into the heating furnace and a flow rate of a gas supplied from the second pipe into the lowermost compartment to be substantially constant.

Abstract: An apparatus includes: an introducer to introduce a glass optical fiber that has passed a pulling mechanism pulling, to draw the glass optical fiber, one end of an optical fiber preform that has been fused by heating; a shredder including a casing connected to the introducer and a shredding mechanism to shred the glass optical fiber introduced by the introducer in the casing into glass optical-fiber pieces; a pipe connected to the casing of the shredder and to carry the glass optical-fiber pieces; and a suction unit connected to the pipe and to suction the glass optical-fiber pieces via the pipe.

Abstract: In an apparatus for fabricating an optical fiber, the apparatus includes a drawing furnace provided with an insertion opening for receiving an optical fiber perform, a feed mechanism configured to support one end of the optical fiber preform so as to feed into the drawing furnace, a first sealing unit configured to seal a clearance gap between the optical fiber preform and the insertion opening, and a second sealing unit configured to seal a gap between the optical fiber preform and the first sealing unit when a tapered portion formed at the one end side of the optical fiber preform passes through the insertion opening. As a result, the available entirety of the optical fiber preform can be changed to an optical fiber, so that the cost for fabricating the optical fiber can be significantly reduced.

Abstract: A method of manufacturing an optical fiber includes providing a preform in a furnace, and drawing a plurality of optical fibers from the preform at a plurality of different draw tensions. A bandwidth characteristic of each of the optical fiber is drawn at the different draw tensions is measured. A draw tension setpoint is selected based on the measured bandwidth characteristic of each optical fiber and the draw tension is adjusted to the selected draw tension setpoint. The method further includes drawing from the preform a tuned optical fiber at the selected draw tension setpoint which provides peak bandwidth.

Abstract: To provide a method for the inexpensive manufacture of a deposition burner with small manufacturing tolerances for use in the synthesis of quartz glass, and wherein moreover, when the deposition burner is used as intended, the risk of contamination of the quartz glass to be produced is low, the invention suggests the following method steps: (a) providing a start cylinder of quartz glass (40) which is mechanically provided with longitudinal bores (46, 47); (b) elongating the start cylinder with formation of a burner strand (42), the longitudinal bores being shaped as elongated channels extending in parallel with one another; (c) cutting the burner strand into pieces in the form of cylindrical quartz glass blocks (43), each being provided with passage lines extending in parallel with a central axis of the quartz glass block; and (d) manufacturing the deposition burner by using a respective one of such quartz glass blocks as burner head which has a proximal end and a distal end, the passage lines serving the sup

Abstract: Drawing methods and drawing furnaces for drawing an optical fiber with small non-circularity by simple drawing system are provided. An optical fiber preform is received into a muffle tube and heated by a primary heater placed to surround the muffle tube. The optical fiber preform is heated such that a starting position of a meniscus portion is higher in its position than the top of the primary heater, wherein the meniscus portion is created at the bottom portion of the optical fiber preform.

Abstract: An optical fiber includes an outer periphery formed into a shape that configures the fiber to interlock with the other fibers with complementary shapes. Methods and systems for fabricating such interlocking fibers are also disclosed. In one example, a method includes drawing a first optical fiber from a preform and forming an outer periphery of the first optical fiber into a shape that configures the first optical fiber to be interlocked with a second optical fiber comprising an outer periphery formed into a shape that is complementary to the shape of the first optical fiber.

Abstract: An optical fiber manufacturing apparatus including: a heating furnace in which an optical fiber is formed by melt-drawing an optical fiber preform; a sealing mechanism which is provided on an opening portion located at an upstream of the heating furnace and seals the heating furnace with an inert gas; a first pipe which is connected to the heating furnace and introduces the gas into the heating furnace; a second pipe which is connected to a lowermost compartment closest to the heating furnace among the compartments and introduces the gas into the lowermost compartment; and a gas flow rate control unit which controls a total sum of a flow rate of a gas supplied from the first pipe into the heating furnace and a flow rate of a gas supplied from the second pipe into the lowermost compartment to be substantially constant.

Abstract: A glass preform drawing apparatus feeds a glass preform into a heating furnace at a predetermined feeding speed and produces a glass rod having a uniform diameter. Specifically, the drawing apparatus for producing a glass rod having a desired outer diameter by heating and drawing a glass preform is characterized in that, at a normal operating temperature T (K) of the heating furnace, the top chamber is transparent at a wavelength of ? (?m) expressed by the following formula 1: ?=2898/T.

Abstract: A furnace for drawing an optical fiber includes a body having an upper and lower openings for supplying a preform and discharging a drawn optical fiber, a heating unit installed in the body for receiving and melting the preform, an atmosphere blocking tube installed to the lower opening for discharging the drawn optical fiber and blocking the optical fiber from the atmosphere, an upper introduction port formed at an upper portion of the body for introducing an inert gas toward the preform and partially discharged outside through a gap between the preform and the upper opening, a central and lower introduction ports formed at central and lower portions for introducing an inert gas into the body, a first flow guiding means for guiding the inert gas introduced through the central introduction port upward and then flowed down along a surface of the preform, and a second flow guiding means for guiding the inert gas introduced through the lower introduction port upward and then discharged outside through the atmosp

Abstract: Provided is a seal member, which is used in a heating furnace having an insertion port to which an end of a rod to be heated is inserted and seals between the insertion port and a surface of the rod inserted to the insertion port in an airtight manner, the seal member having: a plurality of seal chips in thin strips arranged along an inner surface of the insertion port in an airtight manner, each seal chip having one end held by the inner surface of the insertion port and the other end elongated towards inside the insertion port, where (a) when the rod is not inserted in the insertion port, each of the plurality of seal chips forms a slanting angle with respect to an insertion direction of the rod and (b) when the rod is inserted in the insertion port, the other end of each of the plurality of seal chips is pressed against a surface of the rod by means of elastic deformation.

Abstract: An inner seal ring 16 is composed by connecting a plurality of inner seal ring pieces 16A, an outer seal ring 17 is composed by connecting a plurality of outer seal ring pieces 17A provided at an outer periphery of the inner seal ring 16, and a coil spring 18 is arranged at an outer periphery of the outer seal ring 17. The inner seal ring 16 and the outer seal ring 17 are piled for two or more stages, respectively. A connecting part of the inner seal ring pieces 16A and a connecting part of the outer seal ring pieces 17 are arranged not to overlap each other. An inner diameter of the inner seal ring 16 is variable in accordance with an outer diameter in vertical direction of a drawing-preform 1 by using a coil spring 18.

Abstract: The present disclosure relates to a telecommunications cable having a jacket including a feature for allowing post-extrusion insertion of an optical fiber or other signal-transmitting member. The present disclosure also relates to a method for making a telecommunications cable having a jacket including a feature for allowing post-extrusion insertion of an optical fiber or other signal-transmitting member.

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: The present invention provides an optical fiber preform-heating furnace that is simple in its structure and excellent in uniformity of the temperature distribution in a circumferential direction of an optical fiber preform. The optical fiber preform-heating furnace includes a furnace core tube into which an optical fiber preform is supplied; a heater that surrounds the furnace core tube; a pair of electrode connection portions with which the heater is provided and has a face opposing to an outer periphery surface of the furnace core tube; and electrode portions that are disposed to each of the electrode connection portions and connected to a power supply. When a cylindrical heat insulator is disposed between the furnace core tube and the opposing faces, since an outward heat transfer amount from the furnace core tube side through the electrode portion can be reduced, the temperature distribution in a circumferential direction of the optical fiber preform can be improved in its uniformity.

Abstract: The drawing method of the present invention uses a drawing furnace comprising a furnace muffle tube, a furnace body and a heater. According to the method, an optical fiber preform is inserted from the inlet of the furnace muffle tube, the optical fiber preform is melted by means of a heater, under a specified gas atmosphere, and is drawn toward the outlet of the furnace muffle tube by means of a specified drawing tension. The optical fiber preform and the drawing furnace used in this method both satisfy the condition of below-indicated formula (1): L/D?8??(1) wherein L indicates the length of the furnace body in the drawing direction and D indicates the diameter of the optical fiber preform.

Abstract: A method for manufacturing a glass rod (106), which is a parent material of an optical fiber (350), comprising: adjusting a vertical inclination of a standard rod (138) having a predetermined straightness; and heating and elongating a base material (102), which is a parent material of the glass rod (106), along an axis of the standard rod (138), the vertical inclination of which is adjusted, to generate the glass rod (106).

Abstract: A support pin—which is to be inserted into a pin insert hole formed in a seed rod provided at an upper end of a glass preform and suspends and supports the glass preform—is formed by coupling a pin main body having a flange section, a first shaft section, a second shaft section, and a male screw section with an auxiliary pin member having a flange section, a shaft section, and a female screw section. The first and second shaft sections of the pin main body and the shaft section of the auxiliary pin member are provided with claddings which are formed from synthetic resin and have elasticity. The support pin is formed so that the second shaft section of the pin main body covered with the cladding can be inserted into the pin insert hole formed in the seed rod.

Abstract: A furnace is provided. The furnace includes a chamber for heating a portion of a preform to draw a fiber. The chamber has a melt region for melting the preform, and at least one port disposed proximate to the melt region. A purge gas supply is provided for supplying a purge gas into the chamber. The purge gas moves vapor products away from the fiber and exits the chamber through the at least one port.

Abstract: A fiber drawing method according to the present invention is a drawing method of optical fiber for drawing an optical fiber 14 from one end of a fiber preform 13 by softening with heat, wherein the fiber preform 13 is set in a semi-closed space 10, 20 opening in part at a lower end in a fiber drawing furnace, the fiber preform 13 is heated by a heater 15 disposed on the lower end side of this semi-closed space 10, 20, and fiber drawing is carried out with adjusting a quantity of heat dissipation from the upper portion 20 of this semi-closed space.

Abstract: A furnace for drawing an optical fiber provided with a muffle tube (10) and inner tubes (5,5′) connected to the upper end of the core tube, wherein a preform (1) supported by a dummy rod (2) at the upper part thereof is disposed inside the muffle tube (10) and inner tubes (5,5′) so as to be movable downward together with dummy rod (2), the preform (1) is heated and melted by a heater (11) from the outside of the muffle tube (10) and an optical fiber (1a) is pulled out from the lower end of the preform (1); the furnace is further provided with one or a plurality of sets of separating plates (4, 17) adapted to partition a space in the inner tubes (5, 5′) above the preform (1) into a plurality of portions in the advance direction of the preform and disposed in the space, and with gas blowing inlets (8) disposed in the parts of wall surfaces of the inner tubes (5, 5′) which are below the separating plates (4,17) and adapted to blow an inert gas into the inner tubes (5,5′) and the muf

Abstract: A furnace for drawing an optical fiber provided with a muffle tube (10) and inner tubes (5, 5′) connected to the upper end of the core tube, wherein a preform (1) supported by a dummy rod (2) at the upper part thereof is disposed inside the muffle tube (10) and inner tubes (5, 5′) so as to be movable downward together with dummy rod (2), the preform (1) is heated and melted by a heater (11) from the outside of the muffle tube (10) and an optical fiber (1a) is pulled out from the lower end of the preform (1); the furnace is further provided with one or a plurality of sets of separating plates (4, 17) adapted to partition a space in the inner tubes (5, 5′) above the preform (1) into a plurality of portions in the advance direction of the preform and disposed in the space, and with gas blowing inlets (8) disposed in the parts of wall surfaces of the inner tubes (5, 5′) which are below the separating plates (4, 17) and adapted to blow an inert gas into the inner tubes (5, 5′) and the

Abstract: The glass base material drawing apparatus for heating and drawing a glass base material has a storage unit for storing the glass base material having an opening unit that is opened along the longitudinal direction of the storage unit when the glass base material is placed inside the storage unit, a heating unit for heating the glass base material that has been stored inside the storage unit via the opening unit, and a pull-out unit for pulling out the glass base material heated by the heating unit. The opening unit may be opened in such a manner that the glass base material is moved from a side direction of the storage unit into the interior of the storage unit. A main axis for supporting the glass base material is connected to the glass base material. The storage unit may have a penetration hole through which the main axis is inserted when the opening unit is closed.

Abstract: A method for fusing an optical fiber preform comprises fusing the preform while blowing an oxidative gas against the preform to be fused from upper and lower directions of a fusing burner unit. An apparatus for carrying out the method includes a plurality of nozzles for preventing deposition of silica cloud, which are each set at an angle, &thgr;, of blowing the oxidative gas relative to the preform being drawn such 20°≦&thgr;≦60°.

Abstract: Disclosed herein is a draw tower for optical fiber producing systems. The draw tower supports a preform feed unit, a furnace, a spinning nozzle, a diameter gauge, and a coating unit thereon. The draw tower includes a plurality of vertically assembled frames. Each of the frames consists of a hollow column vertically erected at each corner to form a square structure, a plurality of horizontal beams horizontally extending between the upper ends and the lower ends of the columns, and a cantilever beam diagonally connected between the columns. The cantilever beam of at least one upper frame has a cross-sectional area smaller than that of a conventional cantilever beam, thus reducing weight of the upper part of the draw tower. The hollow columns of at least one lower frame each have the same cross-sectional area as that of a conventional hollow column while having thicker walls than a conventional column, thus reinforcing the lower part of the draw tower in addition to preventing vibration of the draw tower.

Abstract: There is provided an optical fiber drawing furnace capable of drawing an optical fiber having small non circularity, which drawing furnace includes a muffle tube, in which an optical fiber preform is supplied, a heater surrounding the muffle tube, a plurality of electrode connecting portion extending from the heater, a plurality of electrodes connected to electrode connecting portions, and in conjunction therewith to an electric power source, and unifying means for unifying the temperature distribution along the circumferential direction.

Abstract: The present invention provides an optical fiber preform-heating furnace that is simple in its structure and excellent in uniformity of the temperature distribution in a circumferential direction of an optical fiber preform. The optical fiber preform-heating furnace includes a furnace core tube into which an optical fiber preform is supplied; a heater that surrounds the furnace core tube; a pair of electrode connection portions with which the heater is provided and has a face opposing to an outer periphery surface of the furnace core tube; and electrode portions that are disposed to each of the electrode connection portions and connected to a power supply. When a cylindrical heat insulator is disposed between the furnace core tube and the opposing faces, since an outward heat transfer amount from the furnace core tube side through the electrode portion can be reduced, the temperature distribution in a circumferential direction of the optical fiber preform can be improved in its uniformity.

Abstract: An optical fiber preform suspending and supporting apparatus able to prevent deformation of a pin placed in a high temperature environment and able to support a porous optical fiber preform without adversely influencing supports of the pin and without causing inclination relative to the vertical line of a main shaft, wherein a movable connector is fitted into an enlarged-diameter portion of the lower end of a main shaft, this enlarged-diameter portion is connected with the movable connector by a pin so that the movable connector is able to swing around the pin, a holding portion including a supporting portion is formed integrally at the bottom of the movable connector to hold an enlarged-diameter portion of the upper end of a starting preform, and the diameter of the pin is in the range of 20% to 50% of the outside diameter of the enlarged-diameter portion of the lower end of the main shaft, and an optical fiber processing apparatus including the same.

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: An optical fiber drawing furnace, comprising a furnace core tube where an optical fiber preform is inserted, fused with heat by a cylindrical heating element that is provided around the furnace core tube, and drawn to an optical fiber, wherein a protective tube is provided being contacted with an upper end edge of the furnace core tube.

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 drawing apparatus 1 has a drawing furnace 11 for heating and drawing an optical fiber preform 2, and a carbon heater 13 is disposed in this drawing furnace 11. The carbon heater 13 has a heating portion the length of which in a drawing direction is set to not less than 280 mm. The carbon heater 13 heats the preform so that a maximum temperature on the surface of the optical fiber preform 2 in the drawing furnace 11 becomes below 1800° C. The optical fiber preform 2 is drawn in a state in which the temperature of the muffle tube 12 of the drawing furnace 11 is kept below 1800° C., so that atomic arrangement in the optical fiber preform 2 becomes relatively aligned in a state of reduced randomness of atomic arrangement. This permits the optical fiber 3 to be drawn as reflecting the reduced randomness state of atomic arrangement, whereby the optical fiber 3 can be obtained with reduced Rayleigh scattering intensity and lowered transmission loss.

Abstract: An optical fiber preform suspending and supporting apparatus able to prevent deformation of a pin placed in a high temperature environment and able to support a porous optical fiber preform without adversely influencing supports of the pin and without causing inclination relative to the vertical line of a main shaft, wherein a movable connector is fitted into an enlarged-diameter portion of the lower end of a main shaft, this enlarged-diameter portion is connected with the movable connector by a pin so that the movable connector is able to swing around the pin, a holding portion including a supporting portion is formed integrally at the bottom of the movable connector to hold an enlarged-diameter portion of the upper end of a starting preform, and the diameter of the pin is in the range of 20% to 50% of the outside diameter of the enlarged-diameter portion of the lower end of the main shaft, and an optical fiber processing apparatus including the same.

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: An apparatus and method for drawing low loss fluoride glass fibers from a preform. A stream of reactive gas is passed around the preform and fiber so as to prevent moisture and oxygen contamination of the fiber while the fiber is being drawn. The apparatus includes an insulating vessel which surrounds a heating chamber in which the fiber is drawn, and a very narrow heating zone within the chamber for preventing crystallization of the drawn fiber.

Abstract: The present invention provides an improvement to a fiber optic draw furnace having a heating element (22) arranged inside a furnace shell (20) for drawing an optical fiber (F) from a preform (P). The fiber optic draw furnace (10) has one or more pieces of fiber draw furnace insulation (14, 16, 18) to separate the heating element (22) from the furnace shell (20) for reducing the thermal transfer therebetween. At least one of the pieces of fiber draw furnace insulation (14, 16, 18) is made from rigidified high purity graphite felt that provides highly efficient thermal insulation between the heating element (22) and the outer furnace shell (20). The rigidified high purity graphite felt insulation (14), (16, 18) includes either a bottom insulation ring (14), a cylindrical insulation insert (16) or a cylindrical insulation canister (18).

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: In a heating furnace which holds at least one end of a glass rod with a holding portion and elongates the glass rod by softening the glass rod successively from the other end portion thereof with heating while applying a tensile force thereto, the heating furnace comprises a tubular portion through which the glass rod to be elongated is inserted such as to be longitudinally movable; heater, positioned within the tubular portion such as to circumferentially surround the glass rod, for heating the glass rod; a moving portion through which one end of the glass rod is inserted; bellows the ends of which are respectively secured to the moving portion and the tubular portion and which is longitudinally expandable and contractible and composed of at least a double cylinder surrounding the part of the glass rod such as to block an outside air from flowing into the heating furnace; and gas supply line for supplying, for purging, an inert gas into a space within the tubular portion and the inner bellows as well as the

Abstract: A furnace minimizes the lowering of the quality of optical fibers, especially those lowerings of the quality that stems from variations of the conditions inside of the furnace. These variations can occur when a preform is connected to an auxiliary quartz rod of differing diameters. Also, the furnace has an inlet sleeve which minimizes fluctuations in flow speed of the inert gases and the pressures inside the furnace.