Abstract: The present invention provides an apparatus and a method for fabricating a glass rod from a glass preform capable of suppressing a diameter fluctuation of the drawn glass rod even when there is a relatively large diameter reduction ratio between the glass preform and the glass rod, such as 60 to 95%. The diameter (D) of the glass preform for determining the ratio from a measured diameter data is acquired from measured diameter data of the glass preform, the measured diameter data is obtained by measuring the diameter of the glass preform along the longitudinal length of the preform before drawing the glass preform, and the feed speed (V1) is determined so that the feed speed (V1) varies depending on fluctuations of the measured diameter data in the longitudinal direction.

Abstract: Provided is a method of manufacturing an optical fiber base material having at least four layer including a core, a first cladding, a second cladding containing fluorine, and a third cladding. The manufacturing method comprises preparing a starting base material that includes the core and the first cladding; forming a porous intermediate glass base material by supplying glass raw material and oxygen to a high-frequency induction thermal plasma torch to synthesize glass fine particles that are then deposited on a surface of the starting base material; forming an intermediate glass base material that includes the core, the first cladding, and the second cladding containing fluorine, by heating and vitrifying the porous intermediate glass base material in an atmosphere containing fluorine; and providing the third cladding on the outer surface of the intermediate glass base material.

Abstract: Provided is a glass lathe that processes a glass member by heating the glass member with a burner, wherein a reflector that reflects electromagnetic waves is arranged around a portion of the glass member to be heated. The reflector preferably has a spherical surface with a portion removed therefrom, and may be formed of a mirror surface finishing agent for SUS, aluminum, or an aluminum alloy. An inner surface of the reflector is preferably covered by gold, platinum, or rhodium, and an outer surface of the reflector is preferably processed to improve thermal emittance, by applying an infrared light emitting coating thereto.

Abstract: A method of manufacturing an optical fiber preform by depositing glass fine particles onto a surface of a glass rod while the glass rod is reciprocated relative to a plasma torch, including: moving the glass rod in a first direction relative to the plasma torch while the plasma torch is applied to the glass rod and supplied at least with a dopant material and a glass material to deposit the glass fine particles onto the surface of the glass rod, in such a manner that a plasma power is set higher during a first time interval starting from a beginning of the movement of the glass rod in the first direction than during a second time interval starting from an end of the first time interval; and moving the glass rod in a second direction relative to the plasma torch, where the second direction is opposite to the first direction.

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: 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: Provided is a glass base material hanging mechanism that, when hanging a starting member or a glass base material, can tightly (solidly) connect the hanging shaft tube and the hanging component and can vertically align the hanging component and the center of the glass base material.

Abstract: Provided is a glass base material elongation method for elongating a glass base material with a large diameter to manufacture a glass rod with a smaller diameter, the method comprising, when elongating a glass base material that has a transparent glass tapered portion at one end of a trunk portion and a glass tapered portion including a non-transparent glass portion at the other end of the trunk portion, prior to the elongation, fusing a hanging dummy to an end of the transparent glass tapered portion, setting the hanging dummy in communication with a feeding mechanism, inserting the glass base material into a heating furnace beginning with the other end, and performing elongation.

Abstract: A glass base material elongating method of sequentially feeding rod-like glass base materials hung by a glass base material feeding mechanism into a heating furnace, and pulling a glass rod with a smaller diameter by a pulling chuck at a lower part of the heating furnace, includes: aligning, by an alignment guiding device that guides the glass rod, a guiding center of the alignment guiding device with an axis of the glass rod, the alignment guiding device guiding the glass rod between the heating furnace and the pulling chuck.

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 elongating a glass base material to obtain a glass rod having a smaller diameter, using a glass base material elongating apparatus including a feeder at least for the glass base material, a heating furnace, and an elongating mechanism of the glass base material below the heating furnace, is such that a horizontal plane position measuring unit of the glass base material is provided inside or near the heating furnace, the feeder has a glass base material horizontal plane position adjusting unit, and the elongating mechanism has three or more sets of elongating rollers capable of switching between grasping and releasing for keeping the position of the glass rod in the horizontal plane to be constant, and the glass base material is elongated with the position thereof in the horizontal plane kept as targeted by controlling the glass base material horizontal plane position adjusting unit.

Abstract: Provided is a glass lathe that processes a glass member by heating the glass member with a burner, wherein a reflector that reflects electromagnetic waves is arranged around a portion of the glass member to be heated. The reflector preferably has a spherical surface with a portion removed therefrom, and may be formed of a mirror surface finishing agent for SUS, aluminum, or an aluminum alloy. An inner surface of the reflector is preferably covered by gold, platinum, or rhodium, and an outer surface of the reflector is preferably processed to improve thermal emittance, by applying an infrared light emitting coating thereto.

Abstract: The present invention provides an apparatus and a method for fabricating a glass rod capable of suppressing a diameter fluctuation of a drawn glass rod even in a case of a relatively large diameter reduction ratio between a glass preform and a glass rod, such as 60 to 95%. The diameter (D) of the glass preform for determining the ratio from a measured diameter data is acquired, the measured diameter data is obtained by measuring a diameter of the glass preform before being drawn along a longitudinal direction of the preform, and the feed speed (V1) is determined so that the feed speed (V1) varies depending on a fluctuation of the measured diameter data in the longitudinal direction.

Abstract: An optical fiber capable of suppressing an increase of a transmission loss after exposure of the optical fiber to hydrogen or deuterium is provided. The optical fiber has a core region, an inner cladding region surrounding the core region, a trench region surrounding the inner cladding region, an outer cladding region surrounding the trench region, and a refractive index varying region arranged between the inner cladding region and the trench region, the refractive index varying region having a refractive index gradually increasing from the trench region to the inner cladding region.

Abstract: The present invention provides a apparatus and a method for fabricating a glass rod capable of suppressing a diameter fluctuation of a drawn glass rod even in case of a relatively large diameter reduction ratio between a glass preform and a glass rod, such as 60 to 95%. A feed speed V1 of the glass preform is set to a constant value, a diameter D of the glass preform is acquired for determining the drawing speed V2 from a measured diameter data of the glass preform before being drawn at a diameter acquisition position defined with respect to a reference position of the furnace, and a distance from the reference position to the diameter acquisition position is defined so as to vary depending on a diameter fluctuation of the glass preform before being drawn in a longitudinal direction thereof.

Abstract: There is provided a manufacturing apparatus of a porous glass base material which can prevent soot from being formed on an upper surface (ceiling) of the process chamber, and reduce the amount of soot that comes off the upper surface and falls. A manufacturing apparatus of a porous glass base material 4 deposits glass particles produced by subjecting a material gas to flame hydrolysis, onto a starting member 1 placed vertically. Here, a plurality of gas inlets 5 are provided in one or more lateral walls of a process chamber including a burner 2 for the deposition therein, in upper portions of the lateral walls and along a ceiling of the process chamber.

Abstract: Provided is a method of manufacturing an optical fiber base material having at least four layer including a core, a first cladding, a second cladding containing fluorine, and a third cladding. The manufacturing method comprises preparing a starting base material that includes the core and the first cladding; forming a porous intermediate glass base material by supplying glass raw material and oxygen to a high-frequency induction thermal plasma torch to synthesize glass fine particles that are then deposited on a surface of the starting base material; forming an intermediate glass base material that includes the core, the first cladding, and the second cladding containing fluorine, by heating and vitrifying the porous intermediate glass base material in an atmosphere containing fluorine; and providing the third cladding on the outer surface of the intermediate glass base material.

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 method of manufacturing an optical fiber preform by depositing glass fine particles onto a surface of a glass rod while the glass rod is reciprocated relative to a plasma torch, including: moving the glass rod in a first direction relative to the plasma torch while the plasma torch is applied to the glass rod and supplied at least with a dopant material and a glass material to deposit the glass fine particles onto the surface of the glass rod, in such a manner that a plasma power is set higher during a first time interval starting from a beginning of the movement of the glass rod in the first direction than during a second time interval starting from an end of the first time interval; and moving the glass rod in a second direction relative to the plasma torch, where the second direction is opposite to the first direction.

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.