Shin-Etsu Chemical Co., Ltd.

Hiroyuki Koide

Hideo Hirasawa

Dai Inoue

Takaaki Nagao

Tadakatsu Shimada

Hiroshi Tsumura

Masami Terashima

Kazuhiro Hamaguchi

Yuuji Tobisaka

Hiroshi Oyamada

Hitoshi Iinuma

Kazuhisa Hatayama

Go Ogino

Takeshi Kamio

Hirofumi Kase

Goh Ogino

An optical fiber base material manufacturing method includes: supplying oxygen, hydrogen, and silicide to a core deposition burner; depositing silicon dioxide; adjusting a drawing up speed so that a deposition tip position remains at the same position in accordance with growth of a porous base material; calculating an average of the drawing up speed at each preset time interval; calculating a difference of the calculated average from a preset value of the drawing up speed; correcting a flow rate of silicon tetrachloride when the supplied hydrogen is hydrogen produced or stored at normal temperature, and correcting a flow rate of hydrogen when the supplied hydrogen is hydrogen obtained by vaporizing liquid hydrogen, where when correcting the flow rate of hydrogen, a flow rate of hydrogen supplied to a cladding deposition burner is also corrected in a ratio of before and after the correction of the flow rate of the hydrogen.

Optical fiber preform manufacturing method and optical fiber preform manufacturing device

Provided is a quartz glass manufacturing method that involves using one or more burners, supplying hydrogen and oxygen to the one or more burners to generate an oxyhydrogen flame, introducing a silicide into the oxyhydrogen flame, forming a porous base material by depositing silicon dioxide generated from a flame hydrolysis reaction with the silicide, and heating and sintering the porous base material to form transparent glass, the method comprising supplying hydrogen that is stored or made at a normal temperature to the one or more burners; controlling a hydrogen flow rate using a measurement apparatus or control apparatus that performs measurement based on heat capacity of a gas; vaporizing liquid hydrogen stored in a low-temperature storage chamber, and supplying the vaporized liquid hydrogen to the one or more burners as backup hydrogen; switching from the hydrogen to the backup hydrogen; and when switching, adjusting the hydrogen flow rate to a value obtained by multiplying the hydrogen flow rate immediately after switching by a predetermined correction coefficient.

Quartz glass manufacturing method using hydrogen obtained by vaporizing liquid hydrogen

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.

Method of manufacturing optical fiber base material and apparatus of the same

There is provided an apparatus for supplying a hydrogen gas to a quartz glass manufacturing apparatus including a burner that generates an oxyhydrogen flame when supplied with the hydrogen gas, where the apparatus includes: a first hydrogen supply system that supplies a hydrogen gas in which isomers are in equilibrium; a second hydrogen supply system that supplies a hydrogen gas in which isomers are out of equilibrium; a flow rate control section that includes: a valve that changes a flow rate of the hydrogen gas to be supplied to the burner; a first flow rate measuring section that measures the flow rate of the hydrogen gas to be supplied to the burner by measuring a heat capacity; and a control section that controls the valve in such a manner that a measured value obtained by the first flow rate measuring section approaches a set value input from outside; a second flow rate measuring section that measures the flow rate of the hydrogen gas to be supplied to the burner by measuring a different factor than the heat capacity; and a set value compensating section that compensates the set value by multiplying the set value by a ratio between the measured value obtained by the first flow rate measuring section and a measured value obtained by the second flow rate measuring section.

Apparatus and method for supplying hydrogen gas, and quartz glass manufacturing apparatus

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.

Provided is hydrogen supply equipment that, when switching hydrogen supplied to equipment using hydrogen from (i) hydrogen produced at a normal temperature or hydrogen stored at a normal temperature to (ii) hydrogen stored at a low temperature, supplies the equipment using hydrogen with normal hydrogen obtained by returning the hydrogen at the low temperature to a normal temperature and then passing this hydrogen through equipment for accelerating a conversion from parahydrogen to orthohydrogen.

Hydrogen supply equipment

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.

Apparatus for manufacturing glass base material and a method for manufacturing glass base material

An apparatus for grinding a glass base material having a core and a clad comprising: a grinding wheel for grinding the clad; a measuring unit for measuring an eccentricity between a center position of the glass base material and a center position of the core at a plurality of positions along a longitudinal direction of the glass base material; a design unit for calculating target diameters substantially continuous throughout the longitudinal direction of the glass base material so that the eccentricity becomes substantially zero for each of the plurality of positions; and a control unit for controlling the grinding wheel to grind the clad so that a diameter of the glass base material to be the target diameter substantially continuous throughout the longitudinal direction of the glass base material based on the target diameters calculated by the design unit.

Method for manufacturing glass base material and glass base material grinding apparatus

Apparatus ( ) for sintering a glass base material ( ) which is a base material for an optical fiber. The sintering apparatus ( ) includes: a control unit which varies a condition for sintering the glass base material; and a furnace ( ) which sinters the glass base material by heating the glass base material in an atmosphere of dehydration gas and inert gas. The control unit includes a drive source ( ) which supplies the glass base material to the furnace at various speeds. The control unit includes a temperature control unit which controls the temperature of a heating source provided in the furnace.

Apparatus for sintering a porous glass base material and a method therefor

Proposed is an improvement in the VAD process for the preparation of a porous silica glass preform for double-core optical fibers by using three oxyhydrogen flame burners installed one above the other in a flame hydrolysis chamber in which a porous silica glass body consisting of the center core portion formed by the lowermost burner, side core portion formed by the middle burner and the cladding layer formed by the uppermost burner is gradually pulled up as it grows under rotation. Different from conventional procedures in which the extension of the nozzle axis of each of the burners intersects with the rotation axis of the growing body, the extension of the nozzle axis of the middle burner for the side core is displaced in a horizontal direction by a limited distance not to intersect nor to be in parallel with the rotation axis in the invention. By this means, an improvement is obtained in the uniformity of distribution of the refractive index in the side core which otherwise is remarkably disordered.

Method for the preparation of a porous silica glass preform for optical

An improvement is proposed in the process for the preparation of a porous silica glass preform as a precursor of optical fibers by the VAD method, in which fine silica particles produced by the flame hydrolysis of a silicon-containing compound are deposited on the lower end of a seed rod suspended at the lower end of a suspender rod rotated by a carriage in a vertical tubular reactor furnace to grow in the vertical direction. Instead of taking the fully grown porous preform out of the tubular furnace by pulling up as suspended on the suspender rod as is undertaken in the prior art, the seed rod is temporarily held by clamping with a holding device with disconnection from the suspender rod and the porous preform and seed rod are pulled up by a separate vertical driving device so that the overall height of the apparatus can be greatly decreased contributing to a reduction of the manufacturing cost of optical fibers of silica glass.

Method for pulling-up a porous silica glass preform

An improvement is proposed in the apparatus and method for the preparation of a transparent silica glass preform as a precursor of optical fibers by sintering and vitrifying a porous silica glass preform in a sintering furnace as vertically suspended at the lower end of a suspender rod rotated by a carriage. Different from the conventional process in which the porous preform is lowered into the sintering furnace and the transparent preform after vitrification is pulled up out of the furnace as suspended at the lower end of the suspender rod throughout, a separate vertical driving device is provided along with a horizontal driving device for the carriage so that the effective up-and-down stroke of the carriage can be greatly reduced and the apparatus as a whole can be by far more compact contributing to the reduction of the manufacturing costs of the optical fibers of silica glass.

Method of lowering and raising a optical fiber preform in a sintering

An improvement is proposed in the method for the flame hydrolysis of a silicon-containing gas, e.g., silicon tetrachloride, to produce fine silica particles to be deposited on a substrate in a process for the preparation of a silica glass preform of optical fibers by using a fivefold concentric multiplex-tube burner nozzle. In contrast to the conventional way for the flame hydrolysis in which the center or first nozzle opening of the burner serves for ejection of a mixture of silicon tetrachloride and oxygen and hydrogen is ejected from the third nozzle opening while argon is ejected from the second nozzle opening inbetween, the gas ejected from the second nozzle opening is, instead of argon alone, a mixture of oxygen and argon in a specified mixing proportion so that deposition of silica particles on the nozzle end can be prevented even when the feed rate of silicon tetrachloride is relatively high.

Growing community of inventors

Ibaraki, Japan

Hiroyuki Koide