A multiple tube burner for synthesizing a porous material includes three or more glass tubes are arranged coaxially with one another, the glass tubes having a substantially circular shape on a cross section perpendicular to a longitudinal direction. Out of the three or more glass tubes, a first glass tube and a second glass tube that is arranged on an outer side of the first glass tube are connected with each other on a gas introducing side, and a thickness near a joint portion of the second glass tube connected with the first glass tube is thicker than a thickness of the second glass tube on the gas spouting side.

A manufacturing method of a porous glass preform for optical fiber by depositing glass microparticles on a starting member, including supplying a vaporizer with organic silicon compound raw material in a liquid state and a carrier gas; in the vaporizer, mixing and vaporizing the organic silicon compound raw material in a liquid state and the carrier gas to convert the organic silicon compound raw material and the carrier gas into a raw material mixed gas; supplying a burner with the raw material mixed gas and a combustible gas, combusting the raw material mixed gas and the combustible gas in the burner, and ejecting SiO.sub.2 microparticles generated by the combustion from the burner; and depositing the SiO.sub.2 microparticles ejected from the burner on the starting member by repeatedly moving the vaporizer and the burner together, in a synchronized manner, parallel to the starting member in a longitudinal direction thereof.

An optical fiber preform manufacturing apparatus comprising a seal member, wherein the seal member is attached to a flange portion formed in an open portion of a reaction chamber into which a burner is inserted, the seal member includes a first sheet that is flexible and includes an open portion that is smaller than an outer diameter of the burner, through which the burner is inserted; a second sheet having the same thickness as the first sheet and including an open portion that is larger than an outer diameter of the first sheet; and two third sheets that each include an open portion that is larger than the outer diameter of the burner and smaller than the outer diameter of the first sheet, the second sheet is arranged in the same plane as the first sheet, and the first and second sheets are sandwiched by the two third sheets.

A burner head actuator for lubricating glassware molds of a glassware forming machine includes a base mount and a guide post carried by the mount. A gearbox housing carried on the guide post carries a gear train including drive and driven gears. A servomotor is coupled to the gearbox. A burner head arm is carried by the gearbox housing and coupled to the driven gear for rotation relative to the gearbox housing about an arm axis. The arm includes a burner head leveling gear train including a drive sprocket direct-driven by the driven gear about the arm axis and a driven sprocket driven by the drive sprocket via a chain. The servomotor rotates the gearbox drive gear, thereby rotating the gearbox driven gear and burner head arm, and thereby rotating the leveling gear train so that the burner head remains level as the arm is rotated about the arm axis.

An optical fiber base material manufacturing apparatus including a reaction chamber; a burner that has a portion thereof inserted into the reaction chamber through an insertion opening that creates a connection between the inside and outside of the reaction chamber, and emits a flame toward a starting member positioned within the reaction chamber; and a seal connection member that creates an air-tight seal between the burner and the reaction chamber at the insertion opening. One end of the seal connection member firmly contacts the burner inserted therethrough, another end of the seal connection member firmly contacts the reaction chamber and has a through-hole formed therein through which the burner is inserted without contacting the seal connection member, and the seal connection member includes a connecting portion that connects the one end to the other end, while preventing transfer of stress between the one end and the other end.

A burner for synthesization to synthesize glass particles that form a porous glass base material is provided, the burner for synthesization including a raw material gas injection portion to inject raw material gas toward a target, a combustion assisting gas injection portion to inject combustion assisting gas in a direction in which the combustion assisting gas is merged with the raw material gas at a first merging point, and a combustible gas injection portion to inject combustible gas in a direction in which the combustible gas is merged with the combustion assisting gas at a second merging point that is positioned closer to the combustion assisting gas injection portion than the first merging point. In the above-described burner for synthesization, the combustion assisting gas injection portion may also include a plurality of injection ports arranged along one straight line.

A fabrication apparatus for fabricating a porous glass base material for optical fiber includes a core forming burner configured to form a core-corresponding portion corresponding to a core of optical fiber by depositing glass fine particles onto a hanging seed rod, a first clad forming burner configured to form a portion of a clad-corresponding portion corresponding to a clad of the optical fiber by depositing glass fine particles onto the core-corresponding portion, and a second clad forming burner configured to form a different portion of the clad-corresponding portion by depositing glass fine particles to form an outermost surface of the clad-corresponding portion. Here, a central axis of a flame ejected from the second clad forming burner has such a gradient that the central axis of the flame ejected from the second clad forming burner faces upward relative to a horizontal plane.

A process of forming a titania-silica glass body, the process including exposing a titania-doped silica soot body to a first thermal treatment by heating the body to a first temperature T1 between about 800? C. and about 1100? C. for a first time duration t1 calculated using the equation:

[00001]$t1>\frac{L_c^2}{4?},$

wherein L.sub.c is the characteristic length (cm) of the body and ? is the thermal diffusivity (cm.sup.2/sec) of the body. The process further including exposing the body to a second thermal treatment by heating the body to a second temperature T2 between about 1050? C. and about 1250? C. wherein, after the second thermal treatment, a peak-to-valley difference of hydroxyl concentration amongst a plurality of segments of the body is about 70 ppm or less.

The invention relates to a process for preparing a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt from the silicon dioxide granulate in a melting crucible, and iii.) Making a quartz glass body from at least a part of the glass melt, wherein the melting crucible is comprised in an oven and is made of at least one material comprising tungsten or molybdenum or a combination thereof. The invention further relates to a quartz glass body which can be obtained by this process. Further, the invention relates to a light guide, an illuminant and a formed body, each of which can be obtained by processing the quartz glass body further.

A method for depositing SiO2 soot particles on a deposition surface using at least two mutually spaced and adjacent build-up burners, and a corresponding device for carrying out the method.