A method for producing a component with portions of a rare earth metal-doped quartz glass, an intermediate product containing voids and consisting of a SiO.sub.2 raw material doped with rare earth metal is introduced into a sinter mold the interior of which is bordered by a carbonaceous mold wall, and is melted therein into the component by gas pressure sintering at a maximum temperature above 1500 C. A shield is arranged between the mold wall and the intermediate product. In order to indicate a modified gas pressure sintering method that ensures the production of rare earth metal-doped quartz glass with reproducible properties, a bulk material of amorphous SiO.sub.2 particles with a layer thickness of at least 2 mm is used as the shield, the softening temperature thereof being at least 20 C. higher than the softening temperature of the doped SiO.sub.2 raw material, and the bulk material being gas-permeable at the beginning of the melting of the intermediate product, and the bulk material sintering during melting into an outer layer that is gas-tight to a pressure gas.

A method for producing a component with portions of a rare earth metal-doped quartz glass, an intermediate product containing voids and consisting of a SiO.sub.2 raw material doped with rare earth metal is introduced into a sinter mold the interior of which is bordered by a carbonaceous mold wall, and is melted therein into the component by gas pressure sintering at a maximum temperature above 1500 C. A shield is arranged between the mold wall and the intermediate product. In order to indicate a modified gas pressure sintering method that ensures the production of rare earth metal-doped quartz glass with reproducible properties, a bulk material of amorphous SiO.sub.2 particles with a layer thickness of at least 2 mm is used as the shield, the softening temperature thereof being at least 20 C. higher than the softening temperature of the doped SiO.sub.2 raw material, and the bulk material being gas-permeable at the beginning of the melting of the intermediate product, and the bulk material sintering during melting into an outer layer that is gas-tight to a pressure gas.

A method for manufacturing a glass ingot includes preparing a supply system including a gasifier that gasifies a raw material compound and a burner that combusts the gasified raw material compound; adding an oxygen-containing gas to the raw material compound at a plurality of addition places including an upstream addition place located in the gasifier or on an upstream side of the gasifier and a downstream addition place located on a downstream side of the gasifier in which locations of the raw material compound in a flow direction are different in the supply system so as to form a raw material mixture; and adding the oxygen-containing gas at the upstream addition place so that a concentration of oxygen or a concentration of the raw material compound in the raw material mixture is not in a combustible range of the raw material mixture.

One embodiment of the disclosure relates to a method of cleaning silica-based soot or an article made of silica-based soot, the method comprising the step of treating silica-based soot or the article made of silica-based soot with at least one of the following compounds: (i) a mixture of CO and Cl.sub.2 in a carrier gas such that the total concentration of CO and Cl.sub.2 in the mixture is greater than 10% (by volume, in carrier gas) and the ratio of CO:Cl.sub.2 is between 0.25 and 5; (ii) CCl.sub.4 in a carrier gas, such that concentration CCl.sub.4 is greater than 1% (by volume, in carrier gas). Preferably, the treatment by CCl.sub.4 is performed at temperatures between 600 C., and 850 C. Preferably, the treatment with the CO and Cl mixture is performed at temperatures between 900 C. and 1200 C. The carrier gas may be, for example, He, Ar, N.sub.2, or the combination thereof.

One aspect relates to a method for producing an optical blank from synthetic quartz glass by vitrifying and shaping a porous, cylindrical SiO.sub.2 soot body having a longitudinal axis, in a heating zone including a melt mold with bottom plate. The SiO.sub.2 soot body vitrified in the heating zone at a vitrification temperature so as to form a full cylindrical, completely vitrified, transparent quartz glass body. Subsequently, the vitrified quartz glass body is shaped by softening in the melt mold at a softening temperature so as to form a viscous quartz glass mass which partly fills the volume of the melt mold, and cooling the quartz glass mass and removal from the melt mold so as to form the optical blank. During shaping in the melt mold, the full cylindrical quartz glass body is brought into contact by way of controlled supply with a centering means of the bottom plate.

One aspect is a method for producing a hollow porous quartz glass base material, and a method for producing a synthetic quartz glass cylinder, wherein even when the hollow porous quartz glass base material (soot body) is produced in large weight and high bulk density, the ease of target extraction is maintained and target extraction is performed stably, and a large weight soot body can be produced. The method for producing a hollow porous quartz glass base material comprises: preparing a heat resistant substrate, which has a columnar or cylindrical shape and has an outer surface on which SiO.sub.2 particles are deposited, the outer surface having a surface roughness in which the maximum height Rz is less than 9 m and the arithmetic average roughness Ra is less than 1 m; rotating the heat resistant substrate and depositing SiO.sub.2 particles on the outer surface of the heat resistant substrate to form a glass particulate deposit; and extracting the heat resistant substrate from the glass particulate deposit to produce a hollow porous quartz glass base material.

A torch for fabricating optical fiber preforms may include a body having a surface and two or more slit-shaped orifices oriented parallel or substantially parallel to each other along the surface. The torch body may further include two or more conduits connected to corresponding orifices. The torch may be used by orienting it relative to a preform substrate, and simultaneously emitting two or more gases from corresponding orifices toward the surface of the preform substrate, such that the gases are involved in a reaction to form a soot.

A substrate for an EUV mirror which contains a zero crossing temperature profile that departs from the statistical distribution is provided. A method for producing a substrate for an EUV mirror is also provided, in which the zero crossing temperature profile in the substrate is adapted to the operating temperature of the mirror. A lithography method using the substrate is also described.

The present invention relates to a continuous method for the production of hollow quartz-glass ingots and an apparatus for said method, whereby the hollow quartz-glass ingots are cooled on the internal surface.

A method and apparatus for manufacturing a quartz glass ingot of large cross-sectional area by continuous flame-fusion whereby on-line crack-free cutting of the ingot is ensured by using the internal heat of the ingot to permit equilibration of the internal and surface temperatures while passing through one or more annealing chambers, thus ensuring controlled cooling to temperature at which it is possible to cut the ingot with a water-cooled saw.