A known method for homogenizing glass includes the following steps: providing a cylindrical blank composed of the glass, having a cylindrical outer surface which extends between a first end face and a second end face, forming a shear zone in the blank by softening a longitudinal section of the blank and subjecting it to a thermal-mechanical intermixing treatment, and moving the shear zone along the longitudinal axis of the blank. To reduce the risk of cracks and fractures during homogenizing, it is proposed that a thermal radiation dissipator is used that at least partially surrounds the shear zone, the lateral dimension of which in the direction of the longitudinal axis of the blank is greater than the shear zone and smaller than the length of the blank, the thermal radiation dissipator being moved synchronously with the shear zone along the longitudinal axis of the blank.

In the method for manufacturing a glass-fine-particle-deposited body according to the present invention, at least a part of a gas supplying pipe 25 from a temperature controlled booth 24 to a burner 18 for cladding is temperature-controlled so that the temperature at the burner side becomes high and temperature gradient becomes 5 C./m or more. The temperature control is performed so that the temperature gradient becomes preferably 15 C./m or more, more preferably 25 C./m or more. Specifically, the part is controlled to the predetermined temperature gradient by winding a tape heater 26 that is a heating element on the outer circumference of the gas supplying pipe 25 from the temperature controlled booth 24 to the burner 18 for cladding and temperature-controlling the tape heater 26.

A method of producing bi-modal particles includes the steps of igniting a first precursor gas using a primary burner thereby producing a first plurality of particles of a first size, fluidly transporting the first plurality of particles down a particle tube, igniting a second precursor gas using a secondary burner thereby producing a second plurality of particles of a second size, flowing the second plurality of particles into the first plurality of particles, and capturing the first and second plurality of particles.

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 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 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 method is provided for producing a glass fine particle deposit by a VAD method using a core deposition burner and a cladding deposition burner disposed adjacent to the core deposition burner. The cladding deposition burner including five cylindrical tubes having different outer diameters and concentrically superimposed on one another and a group of small-diameter nozzles arranged in a ring shape in a third region from the inner side. The method includes flowing, in the cladding deposition burner, a glass raw material gas and a combustion supporting gas in a first region from the inner side, air in a second region from the inner side, a combustible gas in the third region from the inner side, a combustion supporting gas in the group of small-diameter nozzles, an inert gas in a fourth region from the inner side, and a combustion supporting gas in a fifth region from the inner side, respectively.

A method of forming an optical fiber preform includes the steps: igniting a burner having a fume tube assembly to produce a first spray size of silicon dioxide particles; depositing the silicon dioxide particles on a core cane to produce a soot blank; and adjusting an effective diameter of an aperture of the fume tube assembly to produce a second spray size of the silicon dioxide particles. The second spray size is larger than the first spray size.

A method for manufacturing quartz glass, wherein (a) an appropriate liquid starting material is evaporated by spraying it into a vertically arranged evaporation chamber, (b) the vaporous starting material is oxidized to form SiO.sub.2, and the SiO.sub.2is collected. The method is characterized in that the starting material to be evaporated is sprayed in on the bottom of the evaporation chamber and the vaporous starting material is removed at the top end of the evaporation chamber, wherein the evaporation chamber is designed such that components depositing in the chamber accumulate on the bottom of the evaporator and are sprayed once again, as well as an evaporator for applying the method.

A method for producing an optical fiber includes stabilizing a burner flame using a multi-nozzle burner. The multi-nozzle burner includes a raw material gas ejection port in a central part for ejecting a raw material gas. The multi-nozzle burner includes a seal gas ejection port on an outer side of the raw material gas ejection port for ejecting a seal gas. The multi-nozzle burner includes a combustible gas ejection port on an outer side of the seal gas ejection port for ejecting a combustible gas. The multi-nozzle burner includes a plurality of small diameter combustion supporting gas ejection ports surrounding the seal gas ejection port in the combustible gas ejection port for ejecting a combustion supporting gas. A gas flow rate of the raw material gas ejection port is V1 and a gas flow rate of the seal gas ejection port is V2, and 1>V2/V1>0.05.