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.

A method for producing synthetic fused quartz is provided. The method includes evaporating a feedstock material which contains at least one polymerizable polyalkylsiloxane compound, and supplying the feedstock material vapor to a reaction zone, wherein the feedstock material vapor is converted by oxidation and/or by hydrolysis into SiO.sub.2 particles. The feedstock material vapor is passed through a membrane filter as a cleaning device to reduce the formation of gel, which is typically associated with the production of synthetic fused quartz.

This raw material supply device supplies a raw material for producing glass fine particle deposits, to a burner and includes a raw material tank; a liquid raw material pipe having one end thereof connected to the raw material tank; a liquid raw material pressure feed pump that pumps siloxane, being a liquid raw material, from the raw material tank via the liquid raw material pipe; a pressure adjustment valve provided on a secondary side of the liquid raw material pressure feed pump in the liquid raw material pipe; an MFC for liquid, connected to the other end of the liquid raw material pipe; and an aeration device that is connected to the secondary side of the MFC for liquid and aerates the liquid raw material. The pipe on the secondary side of the pressure adjustment valve is connected to a location having lower pressure than the primary side pressure.

A porous glass base material manufacturing system that does not require the manufacturing apparatus and building to be hazardous material-compatible and that can provide a stable supply of raw materials, even when organic siloxane raw material is used as raw materials to produce silica fine particles includes a raw material supplying apparatus and a porous glass base material manufacturing apparatus. The raw material supplying apparatus includes: a raw material tank in which organic siloxane raw material in a liquid state is stored and the remaining space is filled with inert gas; a liquid feed pump to pump the organic siloxane raw material from the raw material tank; a circulating piping and a branch piping through which the raw material pumped is passed; a liquid mass flow controller that controls the flow rate of organic siloxane raw material passed through the branch piping to a predetermined flow rate; and a vaporizer.

A device for manufacturing SiO.sub.2TiO.sub.2 based glass by growing a glass ingot upon a target by a direct method. The device includes the target, comprising a thermal storage portion that accumulates heat by being preheated, and a heat insulating portion that suppresses conduction of heat from the thermal storage portion in a direction opposite to the glass ingot.

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.

On an EUV light-reflecting surface of titania-doped quartz glass, an angle () included between a straight line connecting an origin (O) at the center of the reflecting surface to a birefringence measurement point (A) and a fast axis of birefringence at the measurement point (A) has an average value of more than 45 degrees. Since fast axes of birefringence are distributed in a concentric fashion, a titania-doped quartz glass substrate having a high flatness is obtainable which is suited for use in the EUV lithography.

A method for manufacturing an SiO.sub.2TiO.sub.2 based glass upon a target by a direct method, includes: an ingot growing step of growing an SiO.sub.2TiO.sub.2 based glass ingot having a predetermined length on the target by flame hydrolysis by feeding a silicon compound and a titanium compound into an oxyhydrogen flame, wherein the ingot growing step includes: a first step of increasing a ratio of a feed rate of the titanium compound to a feed rate of the silicon compound as the SiO.sub.2TiO.sub.2 based glass ingot grows until the ratio reaches a predetermined value; and a second step of gradually growing the SiO.sub.2TiO.sub.2 based glass ingot after the ratio has reached the predetermined value in the first stage with keeping the ratio within a predetermined range.

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.