Abstract: A first process of the invention comprises forming two constricted portions (28) at a quartz reaction tube (4), charging a solution of a compound of a rare earth element as a solution into the section between the constricted portions (28) for doping. By this, the doping concentration becomes uniform along the length of an optical fiber preform (30) with defects being rarely produced. This process does not involve any complicated operation.A second process of the invention comprises impregnating a solution in the form of a mist in a soot-like core glass (26) by which it becomes possible to control the doping concentration in high accuracy.A third process of the invention comprises impregnating a solution while controlling the concentration in response to a quantity of a transmitted laser beam through a soot-like core glass (26), by which the doping concentration is ensured independently of the density of the soot-like core glass.

Abstract: The invention provides a method of manufacturing extremely precise glass optical element by thermally deforming optical glass on the optical surf ace of a thermal processing jig coated with chemically stable thin film, followed by the molding of optical glass preform having free surf ace on one side and transcribed surface from the optical surface of the thermal processing jig by means of a press mold which thermally presses the optical glass preform.

Abstract: The apparatus for molding an optical glass element is made up of relatively movable upper and lower molds for press molding a glass blank, and a plurality of infrared ray lamps encircling the upper and lower molds, temperature measuring devices for measuring the temperatures of the upper and lower molds, and a controller responsive to the outputs of the temperature measuring devices for controlling electric inputs to the infrared ray lamps thereby maintaining the temperatures of the upper and lower molds at predetermined values.

Abstract: A hermetic coated optical fiber is produced by preparing a bare optical fiber by melting and drawing an optical fiber preform in a fiber drawing furnace and introducing the bare optical fiber in a reactor in which a raw material gas is introduced and forming a hermetic coating film around a surface of the bare optical fiber by a chemical vapor deposition method or pyrolysis in the reactor, wherein a part of an inert gas for purging the fiber drawing furnace which has been heated by a heater equipped in the furnace is exhausted and a rest of the inert gas is introduced in the reactor for diluting the raw material gas.

Abstract: In a VAD method for making optical fiber preforms, the yield is increased by terminating or significantly reducing the supply of glass raw material to the torch (24) just after glass jacket soot (23, FIG. 4) has been deposited at the bottom end of the glass rod (20). The fuel supply to the torch is maintained, however, and the flame continues to be projected from the torch toward the deposited soot boule (23). The rate of vertical movement of the glass rod is increased until the flame is directed at the bottom end (27') of the soot boule. The flame is then allowed to dwell for a sufficient period to increase significantly the temperature of the bottom end of the soot boule and to consolidate partially the bottom end of the soot boule. This has the effect of containing the soot and countering the effects of gravity on the delicate soot boule that might otherwise cause it to crack.

Abstract: The invention relates to techniques for forming fibres from glass or other thermoplastics materials by internal centrifugation associated with gaseous drawing at high temperature. The material to be converted to fibres is poured into a centrifuge, the peripheral face of which is pierced with a vast number of orifices from which the material is sprayed in the form of filaments drawn out into fibres and entrained by a flow of gas at elevated temperature and velocity and directed along the periphery of the centrifuge, cross-wise to the direction in which the fibres are projected and channelled by a layer of cold gases enveloping it which, according to the invention, is formed over the entire perforated height of the peripheral face by diverging individual jets which combine again shortly after the lowest row of orifices in the peripheral face.

Abstract: A glass melter 30 having a mixing impeller 34 for converting a feed stream 38 supplied to a vessel 32 into a vitrified glass melt 50. Heating means such as electrodes 36 or a gas burner 58 are used to heat the glass melt 50. Electrode 36 arrangements are proposed for minimizing current flow through the impeller 34. Current flow through a special continuous circular impeller or conical pump 70 is disclosed. A cylindrical vessel 98, triangular vessel 94, square vessel 32, and hexagonal vessel 96 are disclosed. Methods of processing particular waste streams are disclosed including coated mineral fibers, fly ash, radioactive material, chemical waste and the like.

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: The invention relates to the reception of fibers under fibering machines to obtain a mat of mineral wool. It proposes assigning to each fibering machine its own collecting zone, the surfaces of the collecting zones increasing in the direction of the increase of base weight. The invention also proposes a device characterized by the presence of two reception drums for three fibering machines.

Abstract: There is disclosed an optical waveguide comprising a K.sub.1-x Rb.sub.x TiOmO.sub.4 single crystal substrate, wherein x is from 0 to 1 and M is P or As, having at least one optically smooth surface wherein sufficient K.sup.+ and/or Rb.sup.+ have been replaced by ions selected from at least one of H.sup.+ and NH.sub.4.sup.+ and, optionally, at least one monovalent ion selected from Rb.sup.+, Cs.sup.+, Tl.sup.+, and/or at least one divalent ion selected from Ba.sup.+2, Sr.sup.+2, Ca.sup.+2 and Pb.sup.+2 to chance the surface index of refraction at least a 0.00025 with respect to the index of refraction of the single crystal substrate. One process disclosed for producing an optical waveguide comprises the steps of contacting at least one optically smooth surface of a single crystal of K.sub.1-x Rb.sub.x TiOmO.sub.4 with an ion exchange medium capable of supplying said replacement ions, at a temperature of from about 100.degree. C. to about 600.degree. C.

Abstract: A process for producing a rod glass having a refractive index distribution, which includes pressing a glass at a temperature below the glass transition temperature to form a glass having a density increased towards the surface layer thereof, or alternatively includes heating a glass at a temperature around the transition temperature at the lowest to prepare glass having a uniformly enhanced density and heating the treated glass under a pressure lower than the applied pressure at a temperature below the glass transition temperature of the glass to prepare a glass having a density increased towards the central portion.

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: This invention is directed to a method for producing colored glazes having controlled textures, the method comprising the following steps:(a) a first frit containing a colorant is prepared;(b) a slip of that frit is applied to a glass-ceramic body and dried;(c) a second frit either containing another colorant or being colorless is prepared;(d) a slip of that frit is applied atop the layer of dried particles of the first frit and is dried thereon;(e) the two layers of frit particles are fused into an integral glaze coating.

Abstract: Processes and apparatus for the production of hollow microspheres by thermal expansion of glass particles including the thermal treatment of extremely small glass particles whose dimensions are less than 50 micrometers and, preferably, less than 35 micrometers or even 20 micrometers, which include a fluidizing agent. This technique makes possible the production of extremely small glass microspheres under satisfactory yield conditions. Also, the hollow microsphere products produced by these processes and apparatus.

Abstract: The invention concerns a method and apparatus for producing a carbon coated optical fiber. An optical fiber is drawn through a reactor tube. Reactant gas is flowed into the tube and onto the fiber where it reacts to form a carbon coating on the fiber. The reactant gas and reaction products are flowed in the direction of movement of the fiber and out of an end of the tube and into a receiving chamber having a diameter larger than that of the reaction tube. The reactant gas continues to react as it flows through the tube and after it exits the tube. At least some of the reaction product deposit on the surface of the receiving chamber where it has no adverse effect on the draw process.

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: In a cooling station in a tempering plant for glass sheets for chilling, heat-strengthening, or after-cooling, the cooling station including upper and lower cooling-air blast nozzles are positioned above and below the glass sheets to be cooled. Nozzle covers cover the upper and lower nozzles. The nozzle covers are covered with perforated plates having a reflection coefficient for more than 0.8 for heat radiation. The plates are detachable from the nozzle covers and are thus replaceable.

Abstract: A method of manufacturing distributed index optical elements is disclosed. The method comprises a step of preparing silica sol including at least one of metal dopants, a step of dipping, after subjecting the silica sol to a gelling treatment, the silica gel in an elute into which a part of metal constituents other than silicon including in the gel is selectively eluted, and a step of drying and sintering the silica gel.

Abstract: A glass soot deposit is produced at a high deposition rate by blowing a gaseous glass-forming raw material together with a fuel gas from a combustion burner in a closed muffle, hydrolyzing the glass-forming raw material in a flame to generate glass soot, and depositing the glass soot on a tip end or a peripheral surface of a starting member which is rotated to form a glass soot deposit, in which a lowest surface temperature of the muffle tube is maintained at 50.degree. C. or higher and an average surface temperature of the muffle is maintained in a range between 50.degree. C. and 150.degree. C., whereby corrosion of the muffle is prevented.

Abstract: A porous glass optical fiber sensor, a method for its use, and a method for its manufacture. The sensor includes a glass optical fiber for conveying light, the fiber having a surface of interconnected and permeable chambers within the fiber, for optically sensing within the chambers. An indicator can be applied to the surface for sensing. The sensor is made by: first, drawing the fiber; second, heat treating the fiber to induce phase separation; and third, leaching a phase from the fiber. Thereafter, an indicator, such as a pH or moisture indicator, can be applied to the fiber for sensing. The sensor is used in conjunction with a light source, a light detector, and means for measuring change in the light caused by an agent within the porosity of the sensor.