Abstract: An object of the present invention is to overcome the problems of the prior art technique, and to provide a heat treatment method as well as a heat treatment apparatus capable of heat treating, with higher efficiency, a synthetic quartz glass for optical use having higher homogeneity and higher purity. Another object of the present invention is to provide and a synthetic quartz glass for optical use.

Abstract: A dehydration and consolidation furnace and a dehydration and consolidation method in which gas in a chamber does not leak to a furnace body room and gas in a furnace body room does not leak into a chamber is provided. A furnace of one embodiment of this invention has first muffle tube 3 and second muffle tube 4. The second muffle tube 4 is arranged coaxially around the first muffle tube 3. An optical fiber preform is arranged in this furnace. During the dehydration and consolidation process the pressure of the intermediate room 10 is set lower than a pressure inside the first muffle tube and outside the second muffle tube, and a gas supply and exhaust of the intermediate room 10 are performed independent of the gas supply and exhaust of the first muffle tube and a furnace body room.

Abstract: A silica glass member for use with a light having a specific wavelength of 250 nm or shorter, in which the difference in the maximum and the minimum values of hydroxyl group concentration as measured in a plurality of points within a plane vertical to an optical axis whose center is the crossing point of its optical axis with the optical axis of the silica glass member is 50 ppm or lower; and in which the plurality of signed birefringence values obtained based on the birefringence values measured on several points within a plane vertical to an optical axis whose center is the crossing point of its optical axis with the optical axis of the silica glass member and the direction of the fast axis fall within a range of from −2.0 to +2.0 nm/cm. Thus, a silica glass member having high optical transmittance and a high resistance against ultraviolet radiations is provided.

Abstract: The invention relates to optical glass having improved initial transmittance, formed by subjecting the glass to a hydrogen and/or deuterium treatment at a temperature, and for a duration of time sufficient to diffuse the hydrogen and/or deuterium into the glass.

Abstract: Disclosed is a method for controlling a heat treatment in the process of fabricating a high purity silica glass via a sol-gel process using a low temperature heater having an inhalation line and an exhaust line. Accordingly, the method includes the steps of (a) identifying whether or not the diameter of the exhaust line is varied; (b) controlling the mass flow of the process gas according to the changed diameter of the exhaust line in step (a); (c) measuring an exhaust gas velocity discharged through the exhaust line; (d) comparing the exhaust gas velocity measured in the step (c) with the exhaust gas velocity after the scale of the exhaust line is varied; and, (e) repeating steps (b)-(d) if the comparison result in step (d) is different.

Abstract: This invention provides a synthetic silica glass optical member used together with light having a specific wavelength of 250 nm or less, in which the difference between the maximum value and the minimum value of transmittance [%/cm] per cm in thickness for the light in a predetermined direction within a plane perpendicular to the optical axis is 2.0%/cm or less.

Abstract: A method for heat treating a synthetic quartz glass for optical use in a heating furnace, that comprises covering the surroundings of a synthetic quartz glass body with a SiO2 powder having a mean dissolved hydrogen molecule concentration of 1×1019 molecules/cm3 or higher, and then heat treating the body.

Abstract: A method for producing an optical quartz glass for use in excimer lasers, comprising a step of forming a porous silica preform by depositing silica in a soot-like form formed by flame hydrolysis of a high-purity volatile silicon compound, followed by a step of vitrifying said porous silica preform into transparent glass in an atmosphere containing water vapor and hydrogen, and a vertical type heating furnace for carrying out the production method therein.

Abstract: A method is provided for manufacturing a silica glass that is substantially free of chlorine. The method includes the step of separately expelling a silicon tetrafluoride gas, a combustion gas, and a combustible gas from a burner made of silica glass, the flow velocity of the silicon tetrafluoride gas being within the range of about 9 slm/cm2 to about 20 slm/cm2. The method further includes the steps of producing minute silica glass particles by reacting the silicon tetrafluoride gas with water produced by a reaction of the combustion gas with the combustible gas, depositing the minute silica glass particles on a target, and producing the silica glass by fusing and vitrifying the minute silica glass particles deposited on the target.

Abstract: Disclosed is a method of minimizing re-wetting of a preform upon removal of the preform from the consolidation furnace and producing core cane and/or optical fiber therefrom. During removal, the consolidated preform and, in particular, the centerline aperture is exposed to a heavy inert gas, such as Argon, Krypton or Xenon. This reduces the amount of re-wetting thereby concomitantly improving attenuation of the optical fiber produced therefrom. This method produces beneficial attenuation reductions in the 1383 nm wavelength region.

Abstract: There are provided tube-shaped glass monolith fabricating apparatus and method using a sol-gel process. In the tube-shaped glass monolith fabricating method using a tube-shaped glass monolith fabricating apparatus which has an upper mold including cylindrical portions of different sizes, a lower mold including a first lower cylindrical portion inclined toward the center thereof by a predetermined degree and a second lower cylindrical portion having a vacuum releasing hole, a cylindrical central mold for forming a tube-shaped glass, and a rod-shaped rod, the lower mold, the central mold, and the rod are assembled and a sol is poured in the central mold. Then, an unmixable liquid is poured on the sol, and the upper mold is assembled to the central mold. The sol is gelled in the central mold, the upper mold is removed, a cap is opened to release vacuum, and the rod is removed.

Abstract: An apparatus is provided for producing a glass fiber package. The apparatus includes a heated bushing for supplying streams of molten glass to be drawn into continuous fibers, a rotatable member adapted to draw the streams into fibers and to wind the fibers into a package, an applicator for applying a size to the fibers, and a drying device including a heated element maintained at a temperature of between about 1000.degree. F. and 1500.degree. F. for contacting and transferring energy in the form of heat to the sized fibers to dry the fibers before they are wound into the package. The heating member is stationary while contacting the sized fibers.

Abstract: The invention relates to the production of high purity fused silica glass which is highly resistant to 248 nm excimer laser-induced optical damage. In particular, this invention relates to a fused silica optical member or blank.

Abstract: A method and apparatus are provided for producing composite strands. The apparatus comprises a heated bushing for supplying streams of molten glass to be drawn into continuous first fibers; a drawing device adapted to draw the streams into the first fibers; supply equipment for supplying one or more second fibers of a second material; one or more applicators for applying a size to the first and second fibers; and a device for gathering the first and second fibers into one or more composite strands. The composite stands are made by drawing glass fibers from the bushing; applying sizing to the glass fibers and the second fibers; contacting the fibers with a heated contact plate to dry the fibers; and then commingling the fibers to form one or more composite strands.

Abstract: A glass preform which is used for fabricating an optical fiber, has substantially no bubbles therein and contains sufficient amount of fluorine is produced by a method comprising steps of: forming a porous glass soot body from a glass-forming raw material, removing trapped gas and water from pores of the soot body by heating the soot body under pressure lower than several ten Torr. at a temperature at which the soot body is not vitrified, filling the pores of the soot body with a gas containing SiF.sub.

Abstract: Incidence of breakage in optical fiber drawn from sol-gel produced preforms is reduced by treatment of the still-porous glass by use of a chlorine-containing, oxygen-free gas mixture. Improved satisfaction of proof-rest requirements to at least 100 kpsi is assured by size reduction of unassimilated discrete particles in the fiber.

Abstract: Quartz glass obtained by flame-hydrolyzing a glass-forming raw material to obtain fine particles of quartz glass, having the fine particles of quartz glass deposited and grown on a substrate to obtain a porous quartz glass product and heating the porous quartz glass product to obtain a transparent quartz glass product, which has an OH content of not more than 10 ppm and a halogen content of at least 400 ppm and which contains hydrogen.

Abstract: The invention relates to lenses, prisms or other optical members which are subjected to high-power ultraviolet light having a wavelength of about 360 nm or less, or ionizing radiation, particularly optical members for use in laser exposure apparatus for lithography, and to blanks for such optical members. The homogeneity of the refractive index distribution and the resistance to optical deterioration when the optical members are exposed for a long period of time to short wavelength ultraviolet light from a laser beam are improved. The optical members are made of high-purity synthetic silica glass material containing at least about 50 wt. ppm of OH groups, and are doped with hydrogen.

Abstract: Low attenuation, low dispersion of optical waveguides are provided by a process initiating with axial deposition of a high velocity core soot stream impinging on a target at a high angle of incidence relative to the axis of rotation of the target. A core cylinder is built up axially by relative movement between the soot stream and target during deposition, the movement being non-constant in order to maintain a substantially constant diameter with a constant deposition rate. A cladding layer is then built up by deposition of soot radially on the core. Subsequent drying and sintering provides a vitreous preform which may be drawn directly into optical waveguides. Alternatively, the sintered product may be drawn down to smaller rods, which then are covered with further deposited soot cladding to a desired final thickness, and after further drying and sintering may be drawn to optical waveguides.

Abstract: A method of manufacturing a radiation-resistant optical fiber includes steps of a) heating a bare optical fiber to remove residual hydrogen gas present in the bare optical fiber and b) forming a coating layer consisting of a substance which does not allow permeation of hydrogen gas on the surface of the bare optical fiber from which the residual hydrogen gas has been removed.

Abstract: A process for producing an optical fiber having enhanced radiation resitance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation.

Abstract: A heating furnace for heating a porous preform made of fine particles of quartz base glass for an optical fiber which comprises a heater and a muffle tube positioned inside the heater to separate a heating atmosphere from the heater, wherein the muffle tube body consists of highly pure carbon and an inner wall and an outer wall of the body is coated with a carbon material selected from the group consisting of pyrolytic graphite and solid-phase carbonized glassy carbon.

Abstract: A method for manufacturing optical fibers from halide glass is provided. The method includes the steps of drawing a glass mass into a fiber in a dry gas atmosphere which contains a drying agent. In a further step of the process, an OH band which may still be present can be reduced by treating the fiber with a gaseous drying agent.

Abstract: A process for producing optical fibers of high tensile strength, wherein the fiber is pulled from a glass mass of halide glass and includes surrounding the fiber and mass with a dry gas atmosphere containing a drying agent which reacts with moisture and this dry gas atmosphere includes fluorine-containing agents, in particular NF.sub.3, as the drying agent.

Abstract: A method for producing a glass preform, which method comprises forming a soot preform of glass fine particles comprising SiO.sub.2 by flame hydrolysis or solution hydrolysis of a starting glass material and sintering the soot preform in an atmosphere containing at least SiF.sub.4 to obtain a glass preform which is free from an increase in absorption due to impurities and has sufficiently low attenuation of light transmission.

Abstract: A method for producing a high-purity silica glass powder by calcining a high purity silica gel powder, wherein a vertical-type moving bed apparatus equipped with a heating means is used in a moving bed system such that the feed silica gel powder is continuously supplied from an upper portion of the apparatus and discharged from a lower portion of the apparatus, and wherein a small amount of gas is blown to flow from a lower portion of the moving bed towards an upper portion of the moving bed, and the calcination is conducted at a temperature of from 1,000.degree. to 1,300.degree. C.

Abstract: A process for the preparation of monoliths of aerogels of metal oxides, which aerogel is either constituted by one single oxide, or is constituted by a mixture of oxides, is disclosed, which process consists of the following operating steps:(a) the relevant metal alkoxide(s) is/are mixed with water in the presence of a catalyst of acidic character;(b) the so obtained mixture is hydrolysed;(c) a colloidal suspension of the oxide of a metal equal to, or different from, the metal(s) used in the (a) step is added to the hydrolysate;(d) the so obtained colloidal solution is caused to turn into a gel (gelation) having the desired shape and dimensions;(e) the gel is washed;(f) the gel is dried at values of temperature and pressure which are higher than the critical pressure and temperature values of the solvent used for the washing.

Abstract: A glass preform which is used for fabricating an optical fiber, has substantially no bubbles therein and contains sufficient amount of fluorine is produced by a method comprising steps of: forming a porous glass soot body from a glass-forming raw material, removing trapped gas and water from pores of the soot body by heating the soot body under pressure lower than several ten Torr. at a temperature at which the soot body is not vitrified, filling the pores of the soot body with a gas containing SiF.sub.

Abstract: A process for producing flakes of glass. The process is started by applying a solution containing an organic metal compound to a substrate. The solution is dried and peeled from the substrate. The resultant film is sintered. There is also disclosed an apparatus for producing flakes of glass. The apparatus comprises means 2 for applying solution 1 containing an organic metal compound to a substrate 3 taking the form of a loop, means 4 for drying the film created by the solution containing the organic metal compound, and means 5 for collecting flakes obtained by peeling the dried film from the substrate. The substrate forms a circulatory continuous conveyance path which passes through the applying means, the drying means, and the collecting means in succession.

Abstract: A method for manufacturing optical fibers from halide glass is provided. The method includes the steps of drawing a glass mass into a fiber in a dry gas atmosphere which contains a drying agent. In a further step of the process, an OH band which may still be present can be reduced by treating the fiber with a gaseous drying agent.

Abstract: A substantially dehydroxylated glass is formed by impregnating a dry porous silica gel with a nitrogen-containing organic compound in an organic solvent capable of solubilizing that compound. The impregnated gel is then sintered in a non-oxidizing atmosphere to form a substantially dehydroxylated, fully-densified silica glass. The gel is typically formed by a sol-gel process. The nitrogen-containing organic compound can be guanidine compounds, urea, or mixtures thereof.

Abstract: A method of making an optical waveguide fiber with a fatigue resistant TiO.sub.2 -SiO.sub.2 outer cladding, and a substantially glass blank for drawing into such fiber, wherein a glass soot TiO.sub.2 -SiO.sub.2 outermost layer, with an initial TiO.sub.2 concentration greater than 10.5 wt. %, is deposited on a preform, and the preform is exposed to an atmosphere of chlorine and oxygen at a high temperature, and the resulting TiO.sub.2 concentration in the outermost layer of the TiO.sub.2 -SiO.sub.2 outer cladding of the substantially glass blank is less than the initial TiO.sub.2 concentration. In the glass blank form, the outermost layer includes a substantial volume percentage of crystalline phases and in the fiber form, the outermost layer includes inhomogeneities.

Abstract: A quartz glass crucible for use in a process for pulling a single crystal silicon and having an outer layer and an inner layer. The outer layer contains less than 0.3 ppm each of Na, K and Li and more thant 5 ppm of Al. The outer layer further contains bubbles to present an opaque appearance. The inner layer is made by melting powders of high purity non-crystalline synthetic silica and contains less then 200 ppm of OH group. There is also disclosed a method for producing the crucible.

Abstract: A method for producing a glass preform for use in the fabrication of an optical fiber, which comprises adding fluorine to a soot preform in an atmosphere comprising a fluorine-coating compound at a temperature at which the soot preform is in the porous state and then keeping or inserting it in an atmosphere containing a fluorine-containing compound at a higher temperature to vitrify it to form a glass preform, from which glass preform, an optical fiber homogeneously containing fluorine is fabricated.

Abstract: In a process for manufacturing an optical element, in which a molding material is put in molds and is heated and press-molded to manufacture an optical element, a preheating treatment of the molding material is performed before it is put in the molds at a reduced pressure and a temperature lower than a temperature during the press molding.

Abstract: This invention relates to the production of high purity fused silica glass through oxidation and/or flame hydrolysis of a halide-free, organosilicon-R compound in vapor form having the following properties:(a) producing a gas stream of a halide-free silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO.sub.2 ;(b) passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO.sub.2 ;(c) depositing said amorphous particles onto a support; and(d) either essentially simultaneously with said deposition or subsequently thereto consolidating said deposit of amorphous particles into a virtually nonporous body; the improvement comprising utilizing a halide-free, organosilicon-R compound in vapor form having the following properties:(1) a Si--R bond dissociation energy that is no higher than the dissociation energy of the Si--O bond;(2) a boiling point no higher than 350.degree. C.

Abstract: A silica glass powder suitable for the production of a silica glass body product of a low silanol content, which is obtained by baking a dried silica gel powder obtained by a sol-gel method, at a temperature of from 1,000.degree. to 1,400.degree. C., wherein during the baking period, the silica gel powder is baked in a gas atmosphere containing from 10 to 100% by volume of steam for at least 5 hours.

Abstract: A glass preform is produced by forming a glass soot composite body having a core portion consisting of a solid glass and a peripheral portion consisting of a porous glass mass, removing trapped gas and water from pores of the soot composite body by heating the soot composite body under a pressure lower than several ten Torr. at a temperature at which the porous glass mass is not vitrified, filling the pores in the porous glass mass of the soot composite body with a gas containing SiF.sub.4, the partial pressure of which is a function of the desired specific difference of refractive index, thus uniformly adding fluorine to the soot glass mass, and vitrifying the fluorine-added soot glass mass into a transparent glass mass to form a glass preform.

Abstract: A synthetic silica glass article made by hydrolyzing an alkoxysilane and thermally sintering the resulting silica; this synthetic silica glass article has a viscosity of not lower than 10.sup.10 poise at 140.degree. C., and contains, as metallic impurities, less than 1 ppm at Al, less than 0.2 ppm of Fe, less than 0.2 ppm of Na, less than 0.2 ppm of K, less than 0.01 ppm of Li, less than 0.2 ppm of Ca, less than 0.02 ppm of Ti, less than 0.01 ppm of B, less than 0.01 of P, less than 0.01 ppm of As.

Abstract: This invention relates to a sintering furnace for the production of a quartz preform which can be used for carrying out dehydration, fluorine-addition and/or sintering of a porous quartz soot preform prepared by a flame hydrolysis method such as a VAD method or a OVD method, and in particular, to such a furnace in which joints in a long furnace muffle so long that fabricating it as open body is impossible can be maintained fully gas-tight, so that it is possible to prevent H.sub.2 O, O.sub.2 and other impurities in the air from entering the muffle from outside, and corrosive and poisonous gases in the muffle are prevented from leakage to outside the muffle.

Abstract: The present invention providesa process for the dehydrating and purifying treatment by heating a porous glass preform for an optical fiber by passing the porous glass preform through a muffle tube having a SiC layer at least on its inner surface at a high temperature under an atmosphere containing an inert gas and a silicon halogenide gas;a process for the fluorine-doping treatment by heating a porous glass preform for an optical fiber by passing a porous glass preform through a muffle tube having a SiC layer at least on its inner surface at a high temperature under an atmosphere containing a fluorine compound gas and an inert gas; anda process for the vitrifying treatment by heating a porous glass preform for an opticla fiber by passing the preform, which has been previously dehydrated and purified, through a muffle tube having a SiC layer at least on its inner surface at a high temperature under an atmosphere gas.

Abstract: In order to eliminate the effect of water attack on silica optical fibres, the fibres are provided with a surface layer of silicon nitride or silicon oxynitride. The method proposed includes direct nitridation. This may be achieved by adding a nitriding atmosphere to the drawing furnace gases, or to the reactive gases (TiCl.sub.4 and SiCl.sub.4) incorporated in the flame of an oxyhydrogen torch for the formation of a compressive silica/titania layer on an optical fibre by a glass soot deposition and sintering process.

Abstract: A method of producing glass bodies having regions with different optical refraction, including a basic body and a coating layer which is sintered onto the basic body, covers the basic body at least partially and is made of glass, which as it is doped, has an index of refraction differing from that of the glass of the basic body. The starting material for producing the cladding on the basis of pulverulent ceramic material is deformed into a self-supporting, unsintered porous green body, is dried and submitted to a cleaning procedure in a heated gas phase. The coating layer to be bonded onto the basic body is melted into glass in a subsequent combined doping/sintering procedure in a gas phase containing the doping agent at a temperature in the range from 1150.degree. to 1500.degree. C. and is sintered onto the basic body.

Abstract: The invention relates to lenses, prisms or other optical members which are subjected to high-power ultraviolet light having a wavelength of about 360 nm or less, or ionizing radiation, particularly optical members for use in laser exposure apparatus for lithography, and to blanks for such optical members. The homogeneity of the refractive index distribution and the resistance to optical deterioration when the optical members are exposed for a long period of time to short wavelength ultraviolet light from a laser beam are improved. The optical members are made of high-purity synthetic silica glass material containing at least about 50 wt. ppm of OH groups, and are doped with hydrogen.

Abstract: A mandrel (12) that is used for supporting a glass soot cylinder during consolidation into anoptical fiber preform is coated by chemical vapor deposition with a material selected from the group consisting of pyrolytic graphite and pyrolytic boron nitride.

Abstract: Reproducible doped optical fiber preforms having a predetermined dopant concentration level are fabricated by inserting a doped filament into a completed preform prior to consolidation and final collapse so that the filament and dopant materials are centrally located in the core region upon formation of the preform. Doped fiber is drawn from the doped preform using standard fiber drawing techniques.

Abstract: An optical fiberglass preform having fluorine selectively added to its cladding is produced by:depositing soot of quartz glass on a pipe from starting member by using burners for synthesizing glass soot to form a porous glass preform consisting of a core porous glass body a peripheral portion of which has a larger bulk density than the other portion and a cladding porous glass body,heating said porous glass preform in a dehydration atmosphere while supplying dehydration gas through the pipe form starting member andheating and vitrifying the dehydrated porous glass preform in an atmosphere containing a fluorine-containing compound.

Abstract: Improved fluoride glass optical fibers are produced by a process introducing several improvements in the production of fluoride glass preforms and the drawing of fibers therefrom. Reduced bubble formation and crystallization are obtained by vertically spinning a fluoride glass melt within a glass cladding tube at a high rotational speed, or alternatively, pouring a flouride glass core melt into a cladding tube while slowly raising the mold from an inclined position to a vertical position, or alternatively, introducing a core tube inside a cladding tube. The production of fibers is enhanced if at least one production phase, i.e., preform formation or fiber drawing, is conducted in an atmosphere containing reactive gases that scavenge molecules that could otherwise react with, hydrolyze and oxidize the fluoride glass. The disclosure also describes several devices uniquely useful in the process of the present invention.

Abstract: A preform for preparation of optical fibers is prepared by inserting a rod of a higher index of refraction fluoride glass into the bore of a hollow cylinder of a lower index of refraction fluoride glass fiber. This preform precursor is processed to collapse the hollow cylinder inwardly to form a composite preform having a high-refractive index core and a low-refractive index casing. The preparing of the glasses and processing to a preform are accomplished in a reactive environment that reacts and removes oxygen and hydrogen containing species from the glass, the reactive environment being, for example, Cl.sub.2, CCl.sub.4, SF.sub.6, BF.sub.3, CF.sub.4, or the decomposition products of a liquefied solid fluorocarbon. The preform is then drawn to an optical fiber.

Abstract: A method for producing a glass preform for an optical fiber is disclosed. The method comprises forming a soot preform of glass fine particles comprising SiO.sub.2 by flame hydrolysis or solution hydrolysis of a starting glass material and sintering the soot preform in an atmosphere containing at least SiF.sub.4 to obtain a glass preform which is free from an increase in absorption due to impurities and has sufficiently low attenuation of light transmission.