Abstract: In the process for the production of an optical waveguide preform, in which the cladding layer is applied as a tubular powder layer onto a cylindrical glass core rod and is densified by heating, the powder layer has a relative density of approximately 6 percent, which is increased to 25-50 percent during the stabilization process. In order for this process to proceed without damage to the preform, the powder layer is initially heated at a low heating rate. From approximately 150.degree. C., the heating rate is increased until a higher temperature is reached.

Abstract: A single crystal non-linear optical transmission line is manufactured by using a cladding made of a glass material that eliminates or reduces the formation of an uneven inner wall of an optical fiber cladding made of a glass mother material. The improved glass material suppresses the elution of metal mono-oxides on the inner wall and results in a high yield of non-defective fiber manufacturing. A glass mother material, such as SF1, having a low concentration of lead oxide does not contribute to the elution problem common to higher concentration glass mother materials. A glass mother material having no metal oxides also overcomes the problem of elusion since substitute molecules, such as TaC6, do not elute in water or in acid solutions. These glass materials can be used to successfully form a non-defective core having a low refractive index layer of the inner wall and make possible single mode propagation of a laser light in a single crystal non-linear optical transmission line.

Abstract: A method and apparatus for producing a polymer-clad silica (PCS) optical fiber comprising a core of a transparent inorganic glass and a cladding of a transparent organic polymer characterized in that the amount of volatile components in its cladding is not more than 1 wt %, which method and apparatus comprise forming the core fiber, forming the cladding around the core fiber, and treating the cladding with a far infrared heater.

Abstract: In the optical fiber, the concentration of fluorine doped in the core portion is made nonuniform in the radial direction to be greater at the center portion of the core portion and less at the outer circumferential portion of the core portion. As a result, the distribution of the refractive index of the core portion and the cladding portion before the process of transparent glassification becomes a profile which is high at the outer circumferential portion of the core portion and which is low at the center portion. The reduction of the refractive index at the outer circumferential portion of the core portion due to the dispersion of the GeO.sub.2 etc., the oxide included in the core portion, in the cladding portion in the transparent glassification processed is and as a result, the profile of the refractive index of the core portion becomes one which sticks out in a step form with respect to the cladding portion.

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 method and an apparatus for measuring the thickness of a coating provided around a cylindrical object such as an optical fiber optically. The cylindrical object is irradiated by a measuring light and the light derived from the object is received by a photo-detector so that the intensity of the derived light is measured to thereby detect the thickness of the coating.

Abstract: In a method of producing an optical fiber coupler, in which glass portions of a plurality of optical fibers are heated so as to be fusion bonded to each other and then, are heated so as to be stretched, the improvement comprising: a gas burner which acts as a heat source and has a plurality of gas nozzles arranged in an axial direction of the optical fibers so as to be fixed in position during heating of the glass portions.

Abstract: The present invention is directed to a process for producing hard clad optical fibers with improved ultraviolet transmission which includes drawing an optical fiber core while simultaneously coating the core with a photoinitiator-free, active energy ray curable composition and then introducing the coated core to a high energy ionizing radiation ray source so as to minimize exposure of the core to the ionizing radiation. The energy is less than 800 keV and preferably less than 200 keV. In one preferred embodiment, the energy is aimed at the coated core so as to pass therethrough at an angle of 45.degree. or less. The resulting product from the process is also included in the present invention.

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 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 coated, embrittlement resistant optical fiber thermometer fiber is disclosed, which can be a sapphire or silica fiber with a metallic coating which prevents the fiber from becoming brittle at high temperature, and enhances transmission of radiation through the fiber. The coating can be applied over a thin "conductive" film attached to the fiber exterior using vacuum metallization, sputtering, or organo-metallic deposition. The coating may comprise pure platinum electroplated over a thin conductive film. The fiber may include a first end terminating in a blackbody radiator in a furnace and a second end terminating at a receptor apparatus. A coated fiber of the present invention provides a hermetic seal around the fiber to prevent its exposure to hydroxyl ions in the atmosphere. Fibers of the invention will remain flexible even after exposure to temperatures well over 1000 degrees Centigrade. The coating also prevents unwanted external radiation from entering the fiber.

Abstract: Substrates for supporting optical fibers in an optical coupler are made by, first, making grooves in a glass preform which are about ten times the desired size, and then using glass drawing techniques to draw from the preform a substrate of the proper size. Optical fibers are arranged in ribbon form and placed in a fixture which allows the ends to be cut and polished at the angle required for proper coupler operation. Fibers are stripped from the end of the ribbon that has been cut and polished and placed in the grooves for proper alignment with abutting fibers. The ends of the fibers that remain fixed to the ribbon prevent unwanted rotation of the fibers.

Abstract: An optical interconnect structure, formed on a substrate, optically interconnects optoelectronic transmitting and receiving devices. The optical interconnect structure includes optical interconnects each of which includes a core member constructed of a material having a first predetermined index of refraction. The ends of the core members are chemically bonded either to an optoelectronic device or a core member of another optical interconnect. A cladding layer surrounds each core member. Each end of a cladding layer proximate to an optoelectronic device is chemically bonded to that device. The cladding layer is formed of a material having a second predetermined index of refraction, the magnitude of which is less than the magnitude of the first predetermined index of refraction.

Abstract: A method of forming an optical channel waveguide by gettering includes forming on a substrate a porous waveguide layer containing an index of refraction raising dopant in a compound; sealing a portion of the waveguide layer along a path; and reacting the component, including the index of refraction raising dopant, with a reactant in the unsealed portion of the waveguide layer to form a volatile product from the reactant and dopant to deplete the dopant in the unsealed portion of the waveguide layer and reduce its index of refraction relative to that in the path to produce a channel waveguide along the path.

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: 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 cylindrical piece of glass (4) is subjected to heating passes on a glassmaker's lathe. Possible opto-geometrical defects of said piece of glass are detected and measured and then said defects are corrected by machining the outside surface thereof during a correction pass performed on the same glassmaker's lathe.

Abstract: In a method of manufacturing a preform for a nonoxide glass fiber, cladding and core glass materials are placed in a cylinder of an extrusion apparatus such that ground end faces of the respective cladding and core glass materials are in contact with each other and such that the cladding glass material is located adjacent a molding section of the extrusion apparatus. The cladding and core glass materials are heated within inert-gas atmosphere, to their respective temperatures equal to or below their respective sag points and equal to or above their respective crystallization start temperatures. An extrusion punch of the extrusion apparatus is pushed within the atmosphere, to extrude the cladding and core glass materials through a molding nozzle in the molding section while the cladding and core glass materials are in fusible contact with each other, thereby forming the preform of a core and cladding structure.

Abstract: A silica-based glass rod is inserted into a space portion of a mold. Then, a slurry, which is obtained by dispersing a silica glass powder material in pure water, is poured into a molding space between the glass rod and the inner surface of the mold, whereby a porous glass shaped body is formed around the glass rod. Drying this shaped body results in a silica glass base material which includes the glass rod and the porous glass shaped body surrounding the same.

Abstract: Method of manufacturing tubes in which a mixture of powdered tube material and a liquid binder is introduced into a tubular mold with a geometry corresponding to the geometry of the tube to be formed. The tubular mold is rotated about its longitudinal axis. The powder-binder mixture deposits on the inner wall of the tubular mold. The powder and the liquid are introduced into the tubular mold separately.

Abstract: A gradient index glass comprised of (SiO.sub.2).sub.m (R.sub.2 O).sub.n X.sub.p, wherein R is Li, Na, K, Rb, or Cs, and X=TiO.sub.2, ZrO.sub.2 and/or HfO.sub.2, m is 44 to 99, n is 0.25 to 20, p is at least 0.1, and m+n+p=100.

Abstract: An infrared optical fiber is provided which includes silver halide polycrystals having a composition ratio of silver chloride and silver bromide in the range of 30 to 70 percent by weight of silver chloride, and having an average grain size of 5 .mu.m or less. There also is provided a method of manufacturing such an infrared optical fiber, in which a silver halide single crystal having a composition ratio of silver chloride and silver bromide in the range of 30 to 70 percent by weight of silver chloride is extruded into an infrared optical fiber, while applying an extruding pressure of 70 kg/mm.sup.2 or more and a tensile load which is greater than the yield strength and smaller than the tensile strength.

Abstract: A method of making an optical fiber having an oblong core comprising the steps of depositing layers of core glass particles and cladding glass particles on an enlarged mandrel, removing the mandrel to form a tubular porous preform, consolidating the porous preform to form a dense glass preform, evacuating the central hole of the dense glass preform while stretching that preform to collapse the central hole thereof and form a flattened rod, applying cladding material to the rod, and drawing the resultant composite to form an optical fiber. To facilitate the flat collapse of the central hole of the dense glass preform and to cause the core to have a large aspect ratio, the inside diameter-to-outside diameter ratio of the dense glass preform should be within the range of 0.3 to 0.9. For preferred core and cladding glasses, this ratio should be between 0.5 and 0.6. Also, the mandrel diameter should be at least 12 mm, and it is preferably between 25 mm and 50 mm.

Abstract: A quartz optical waveguide comprising a substrate, a ridge-form core part formed on said substrate and a part which surrounds said core part and has a lower refractive index than that of said core part, wherein a refractive index changes continuously at an interface between said core part and said part having the lower refractive index, which has a decreased transmission loss and a connection loss when connected with an optical fiber.

Abstract: A method of forming an optical waveguide which includes the steps of forming on a substrate a waveguide layer including at least one host medium and one dopant medium, one of which is more volatile than the other; and heating the waveguide layer to selectively volatize the more volatile medium along a path, raising the index of refraction and creating a waveguide along the path.

Abstract: The invention provides a method for producing an optical-fiber coupler with a preset branching ratio. The present invention relates to a method in which part of a plurality of optical fibers are made to closely contact with each other so as to form a coupler. The coupler is heated to thereby obtain a predetermined branching ratio; the flow rate of a gas to be supplied to a heat source is increased/decreased by a quantity proportional to a difference between the drawing speed and a preset drawing speed while predetermined tension is applied to the optical fibers.

Abstract: In a device for performing measurements on at least partly transparent objects such as optical fibres a radiation beam is directed on the object. The radiation deflected by the object is imaged by means of a lens system (321, 322) on a radiation-sensitive detection system (330). As a result of refraction on interfaces between areas having a different refractive index (311, 312) in the object and between the object and the surroundings (315), dark or light bands corresponding to the projection of the interfaces are produced on the radiation-sensitive detection system (330). Thus measurements can be performed on the internal structure of the object.

Abstract: An optical waveguide that has low (0.16 to 0.28 db/km) attenuation but can be subjected to sharp radii of curvature of the order of 2 mm has an index of refraction difference between core and cladding of less than 0.75% and a cutoff wavelength that is 50 micrometers or more greater than the operating wavelength. The waveguide is a "virtual single mode" device, because even though a second order mode can be sustained in the waveguide, the waveguide length or bending losses, or both, differentially attenuates the second order mode so that the primary mode strongly predominates and both modal noise and attenuation are within acceptable limits.

Abstract: In accordance with the present invention, the dopant within one gradient index optical element has two independent concentration distributions. Particularly to use the present invention to obtain a gradient index optical element having an excellent chromatic aberration correction ability, it is only needed to make such dopant distributions as shown in the previously stated Japanese Patent Application No. 280897/1989. However, as to the doping of a dopant into a porous body, there is a limit in the amount which can be doped. This is a disadvantage of the molecular stuffing method, but the reason for this is that the dopant must be supplied into the holes as a solution and it is largely restricted by the solubility of the dopant in the solvent. In addition, since the intra-hole fixing of the dopant depends on the solubility difference by temperature or that by solvent exchange, it is further restricted.

Abstract: A process is known for the tool-free reshaping of a tubular hollow body of amorphous, especially vitreous material to a rod by pressure constriction wherein a pressure depression below atmospheric pressure is sustained in the tubular part by continual evacuation during the constriction, while the hollow body is continually fed horizontally, at a given speed of rotation, to a heating zone, and there its viscosity is so lowered that, as a result of the pressure difference between the absolute value of pressure below atmospheric pressure in the hollow body and the external pressure acting on the hollow body, the hollow body becomes constricted to form a rod in the closing zone and the rod is continually pulled from the closing zone at a given rotatory speed; in order by such a process to produce homogeneous, rod-shaped bodies from hollow bodies in a single procedure and at reasonable cost, the outside dimensions and inside dimensions of the hollow body, the viscosity of the vitreous material in the closing zone,

Abstract: An extruding apparatus having at least two independent inlet ports, one outlet port communicating with the inlet ports, and at least two passages connecting the inlet ports with the outlet port, in which a section of a joint portion of the passages has a central portion and an outer peripheral portion which are concentrically arranged, is prepared. A core material is supplied to one of the passages communicating with the central portion of the joint portion from a corresponding inlet port, and a cladding material is supplied to the other passage communicating with the outer peripheral portion from a corresponding inlet port, thereby causing the two materials to join each other at the joint portion. An integral shaped body having a portion corresponding to a core at its central portion and a portion corresponding to a cladding around the central portion is extruded from the outlet port. Water and a binder and other impurities are removed from the shaped body, and the resultant body is consolidated.

Abstract: A process for producing an optical fiber comprising the following stages: a stage of production of a preform having an axis of symmetry and their ends and comprising an optical core as well as at least one cylindrical recess whose axis is parallel to the axis of symmetry of the preform; a drawing stage at a temperature making possible the softening of the drawn part of the preform to obtain a hollow optical fiber, characterized in that it comprises, after the preceding stage of production of the preform: a stage of attachment in a tight manner, to one end of the preform, of a hollow chamber whose cavity communicates with the recess of the preform. The cavity also communicates with a pneumatic regulation device. The drawing stage comprises a pneumatic regulation of the gas contained in the cavity and in the recess with the help of the pneumatic regulation device.

Abstract: A method for fabricating defect-free optical fiber preforms without light scattering defects such as core-clad interface bubbles, core-clad crystalline inclusions and core glass crystals involves first forming a cladding glass shell preferably by rotational casting, then separately melting core glass inside a cylindrical crucible and quenching using metallic quenching blocks to prevent crystal formation in the core glass, next heating the core containing crucible to the core glass softening point and also heating the cladding tube containing mold to the glass transition temperature of the cladding glass, then placing the cladding tube containing mold inside the core glass crucible and pushing it downwardly with high pressure so that the softened core glass is forced into the cladding glass tube, and finally the preform is annealed to remove thermal stress. Subsequently, the preform is drawn into optical fibers using conventional technology.

Abstract: A preform for a polarization retaining optical fiber is produced by making at least two bores symmetrically around a center axis of a preform comprising a core part and a cladding part which surrounds the core part, decreasing a diameter of one end of each bore, or connecting a glass tube to one end of the preform, the glass tube having a part with a smaller inner diameter near its end which is connected to the preform, inserting a first glass rod, a stressing member and a second glass rod in this order from the other end of each bore or from an end of each bore which is remote from the connected glass tube, contacting the first glass rod to the diameter-decreased end of each bore or to the part with a smaller inner diameter of the glass tube, and heating and fusing the second glass rod to the preform.

Abstract: Germanosilicate optical fiber having substantially higher GeO/GeO.sub.2 ratio than conventional comparison-fiber is disclosed. The fiber has a loss at wavelength of 330 nm of at least 30 db/m.mole % GeO.sub.2. Such fiber can be advantageously used for making in line photorefractive Bragg gratings and other photorefractive fiber components. Fiber according to the invention can be produced by an inside deposition process (e.g., MCVD, PCVD), by an outside deposition process (e.g., VAD, OVD), or even a sol/gel process, and embodiments of the general method of making fiber according to the invention are disclosed.

Abstract: Disclosed is a method of making a polarization retaining single-mode optical fiber. Longitudinal grooves are formed on opposite sides of a cylindrically-shaped core perform having a glass core surrounded by cladding glass. The core preform is inserted into a glass tube, the tube is shrunk onto the core preform, and the interface between the core preform and the tube is fused to form a solid preform having longitudinal apertures on opposite sides of the core. An etchant gas is flowed through the apertures to enlarge the apertures into holes having a substantially round cross-section. Inserted into each aperture is a stress rod formed of glass having a coefficient of expansion different from that of the cladding glass. The resultant draw blank is drawn to form a single-mode optical fiber having a core that is subjected to a stress-induced birefringence.

Abstract: In order to coat successive increments of length of an elongated strand material such as an optical fiber (22), for example, with a marking material, for example, a liquid coating material (40) is circulated through an input section (85) into an inner chamber (71) of a housing (62) and outwardly through an output section (87) to be returned to a reservoir (39). Elongated strand material is advanced through an entry portion into and through the inner chamber wherein it is contacted by the liquid coating material being circulated therethrough. Afterwards, each successive increment of length is advanced through an exit die (73) which causes the liquid coating material to be formed into a layer of predetermined thickness on the elongated strand material.

Abstract: Disclosed is a method of making a polarization retaining single-mode optical fiber. There is initially formed a draw blank having diametrically opposed longitudinal apertures in the cladding glass parallel to the core glass region. The draw blank is drawn into a fiber under such conditions that the apertures close as the fiber is being drawn. The flow of surrounding glass, including the core glass region, toward the collapsing apertures, causes the core to assume an elliptical shape. The apertures are of such cross-sectional area and spacing from the core that the core develops the desired aspect ratio.

Abstract: An optical fiber (24), destined to receive a hermetic coating (32), is moved through a hermetic coating apparatus (30) wherein the fiber, entering the hermetic coating apparatus at a predetermined temperature, is caused to be engaged by a reactive gas. The reactive gas, reacting with the heated fiber, is effective to cause a layer of a hermetic material to be deposited adjacent to the outer surface of the fiber. A cross-flow purge gas is effective to prevent a resultant accumulation of a soot comprising reactive components of the reactive gas adjacent to portions of the hermetic coating apparatus which become heated by the fiber. Failure to prevent the accumulation of the soot may lead to fiber abrasions and reduced fiber strength.

Abstract: A drawn optical fiber (21) is provided with inner and outer layers (42,44) of coating material to protect the optical fiber during handling and use. The coating materials are such that they are characterized by being curable upon exposure to different portions of the light spectrum. In a preferred embodiment, the coating material of the inner layer includes a photoinitiator which absorbs light in the visible portion of the light spectrum whereas the outer coating material of the outer layer includes a photoinitiator which absorbs light in the ultraviolet light portion of the light spectrum.

Abstract: A glass-to-glass hermetic sealing technique is disclosed which can be used to splice lengths of glass fibers together. A solid glass preform is inserted into the cavity of a metal component which is then heated to melt the glass. An end of an optical fiber is then advanced into the molten glass and the entire structure cooled to solidify the glass in sealing engagement with the optical fiber end and the metal cavity. The surface of the re-solidified glass may be machined for mating engagement with another component to make a spliced fiber optic connection. The resultant structure has a helium leak rate of less than 1.times.10.sup.-8 cm.sup.3 /sec.

Abstract: A method of preparing a high Tc superconducting fiber is disclosed, which comprises drawing into fiber form a core filament of a crystalline oxide, continuously depositing on the heated core filament a high Tc superconducting thin film and then depositing a protective layer on the outer surface of the high Tc superconducting thin film.

Abstract: The photorefractive effect results in a change in the refractive index of bulk chalcogenide glass when it is exposed to certain wavelengths of light, in particular, sub-band-gap light. The effect results in a variety of device structures including a fiber optic faceplate; an optical waveguide; a fiber tap; a lens and a Bragg grating. Methods for fabricating the various devices are described.

Abstract: A fiber optic coupler is formed by providing a glass tube having a longitudinal aperture extending therethrough. Glass optical fibers, each having a core, cladding and coating are disposed within the longitudinal aperture, the fibers extending beyond each end thereof. The coating is removed from that portion of the fibers in the midregion of the tube. The midregion of the tube is heated, collapsed about the fibers, and drawn to reduce the diameter thereof over a predetermined length. The fibers that are used in the process of making the coupler are initially provided with a coating that is too thin to provide good handleability and strength. However, the thin initial coating enables the use of a tube having a small aperture and thereby enhances the tube collapse step. After the coupler is formed, the fibers extending therefrom are overcoated. The process can be used to make other kinds of optical devices including integrated optical components.

Abstract: A method is presented for writing a permanent spatially periodic phase-matching second-order non-linearity grating in an optical waveguide. Single frequency exciting radiation is launched in a pair of guided modes of the waveguide in the presence of an external DC electric field applied in a direction transverse to the waveguide. The exciting radiation may be either co-propagating or counter-propagating. The above method may be refined by performing it once for an estimated value of exciting radiation frequency, testing the waveguide to determine error in the chosen estimate, erasing the grating and re-performing the method using a corrected value for the frequency of the exciting radiation.

Abstract: An optical fiber resin coating device having a nipple and a die which each have gradually tapering holes through which the optical fiber is drawn. The die and the nipple have adjacent parallel flat surfaces which are spaced to created a gap through which resin is supplied by pressuring to be applied to the optical fiber. The gap between the die and the nipple and the tapered holes within the die and the nipple are all designed to produce a resin coating which is even and contains no air bubbles, especially at high optical fiber drawing rates.

Abstract: An optical waveguide preform is fabricated by inserting a rod inside a tube and collapsing the tube. The inner diameter of the tube is adjusted before inserting the rod to provide a predetermined gap width between the inner surface of the tube and the outer surface of the rod. The gap width is selected as a function of the cross sectional area of the tube in order to minimize core eccentricity in the finished waveguide.

Abstract: The method includes collapsing a silica-based glass tube to make a preform and drawing fiber from the preform. Prior to collapsing the tube, one or more glass layers are formed on the inner surface of the tube by dip-coating the surface with a sol comprising a metal alkoxide dissolved in an alcoholic or aqueous solvent, polymerizing the sol to form a gel, and drying and sintering the gel. A substantial portion the dopant, present within the sintered gel, diffuses into at least one adjoining glass region. A wide selection of dopant materials, in the form of salts or alkoxides, are readily incorporated by dissolving them in the solvent.

Abstract: The present invention relates to a process for producing a glass doped with dispersed microcrystallites, which glass is used as a material for sharp cut filter, a material for infrared-transmitting filter, a nonlinear optical material, etc. In the process, high-melting semiconductor microcrystallites are precipitated at a temperature T.sub.1 which is lower than the sag point of a glass to be produced but not lower than the transition temperature of the glass, and then low-melting semiconductor microcrystallites are precipitated at a temperature T.sub.2 which is not higher than the flow point of the glass but not lower than the sag point of the glass to obtain a glass comprising a matrix and microcrystallites of semiconductor solid solution of multilayer structure dispersed in said matrix.

Abstract: In the production of an optical waveguide preform, particularly for the production of mono-mode optical waveguides, a tube, or several tubes, of quartz glass are fused onto a crude preform rod of quartz glass. In a known device, the crude preform rod and the quartz glass tube slid over this are clamped at the same end into jaw chucks in the headstock of the glass lathe. Since it happens that optical waveguides that have been drawn from an optical waveguide preform produced with the known device show an inadmissibly high core eccentricity, it is proposed that another jaw chuck be provided in the tailstock for the other end of the tube preform.