Abstract: A pressing plunger apparatus for forming a parison in a glassware forming machine by a blow-and-blow process or a press-and-blow process.

Abstract: A refrigerator having an air-cleaner is provided. The refrigerator includes a main body with a predetermined storage space defined therein, and an air-cleaner including a case fixed to the main body and having at least an inlet and outlet, a decor panel that linearly reciprocates to selectively open and close the outlet, a filter device that filters air sucked through the inlet, a blower that sucks air through the inlet and discharges the air filtered in the filter device through the outlet, and an anion generator that generates anions which are discharged along with the air through the outlet. The air-cleaner is securely mounted to the upper surface of the refrigerator.

Abstract: A press molding apparatus includes upper and lower molding dies each having a molding surface facing each other, and a driving device which moves at least one of the upper and lower molding dies in a vertical direction so that the upper and lower molding dies are opened and closed. The driving device includes a main shaft which supports the at least one of the upper and lower molding dies, an ascending and descending member which, while supporting the main shaft, ascends and descends, a plurality of screw shafts which is located eccentrically from an axis line of the main shaft, and engages a plurality of screws formed in the ascending and descending member in order to move up and down the ascending and descending member, a driver which synchronously rotates each of the screw shafts, and a controller which controls the driver.

Abstract: A punch assembly for producing hollow glass articles in a mold has a punch member, which is moved to and from the mold along a straight axis by an electric motor positioned eccentrically with respect to the straight axis and connected to the punch member by a rotary-to-linear motion conversion assembly, and a releasable angular connecting assembly interposed between the motor and the motion conversion assembly.

Abstract: A plunger mechanism for forming a hollow article of glass in a "narrow neck press and blow" operation which utilizes an electro servo-driven leadscrew to actuate it. A position sensing resolver is used to determine the position of the plunger over the full range of its stroke, and the position information can be used as feedback to control the position of the plunger prior to contacting a molten gob of glass in a mold chamber. The depth of the plunger penetration into the molten gob is then controlled by the pressing pressure, which is a function of motor torque and screw mechanics. It is possible to control the pressure exerted on the molten glass gob by controlling the torque applied by the motor. A separate gob weight controller is not required because changes in gob weight can be determined by closely monitoring the plunger penetration of the gob.

Abstract: Both blow-and-blow and press-and-blow plunger mechanisms for use in forming a parison from a gob of fluid glass in a individual section (IS) of a glassware forming machine are fully pneumatically controlled. Plunger and thimble pistons affirmatively position a thimble and a plunger in consistently repeatable positions during loading of the gob, counterblowing or pressing an initial opening in the parison, and transferring the formed parison. No springs or other mechanical components which are prone to cause inconsistencies or failures are employed. The plunger mechanism is preferably suspended from the frame of the IS by a plunger case assembly to avoid the problems associated with a support foot. The plunger case assembly allows the plunger mechanisms to be easily interchanged or replaced, to be adjusted to accommodate different types of operation and sizes and configurations of glass article produced, while still communicating pressurized air to the plunger mechanisms to achieve these effects.

Abstract: Optical waveguide paths are formed under the surface of a glass substrate by a method comprising (a) forming by ion-exchange a dopant ion path on a first substrate surface, (b) applying an electrode to the second surface, (c) contacting the first surface with a molten salt bath, and (d) applying an electrical field across the substrate to drive the dopant ions deeper into the substrate. The current resulting from high fields can overheat the substrate, thereby causing substrate warping and burying of paths to uneven depths. One aspect of the invention involves cooling the substrate by flowing the molten salt along the first surface of the substrate at a sufficient rate of flow to adequately decrease its temperature and by rapidly flowing the furnace atmosphere over the surface of the substrate. A further aspect of the invention involves initially applying a voltage V.sub.i across the substrate, allowing the current to increase to a predetermined level I.sub.

Abstract: This invention pertains to optical waveguides which includes waveguides of ll shapes and sizes, preforms, and optical fibers made from the preforms, and to a method for making waveguides devoid of a physical interface.

Abstract: Refractive index change in a glass substrate, necessary to obtain a guiding region, is obtained by bombarding the substrate surface with an electron beam. An electric field induced by negative charge accumulation is created under the surface, whereby sodium ions present in glass are made to migrate towards the inside of the substrate.

Abstract: Integrated optical devices are fabricated by field-assisted ion exchange on a starting substrate, wherein the substrate is first prepared to be connected to a source of potential difference, is duly masked as a function of the optical circuit to be implemented and is dipped in a melted salt, which is an ion source for the exchange, with another electrode for applying the electric field capable of inducing ion exchange.

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: Methods of making gradient property refractive elements such as gradient index lens blanks. The spatial distributions of constituents achieved by subjecting various starting assemblages to various diffusion conditions are predicted. Each such predicted spatial distribution of constituents is converted to a spatial distribution of the graded property. The property distribution which best approximates a desired distribution is selected, to thereby select one starting assemblage and one set of diffusion conditions. That assemblage and set of conditions are used in fabrication of the element.

Abstract: In a process for shaping a gob in order to obtain a hollow glass article by means of an electronically-regulated and hydraulically-propelled level, the process of shaping the gob into a rough or finished product is rationally effected in a predefinable and in particular precisely reproducible manner by the fact that an electro-hydraulic servo-drive is used as a means for driving the level, and that the latter, during at least the practically total performance of the movement, is adjusted in position by means of a closed position-regulating circuit. In a device suited for this purpose the drive device of the level consists of an electro-hydraulic servo-drive and an electronic position-adjusting device for the at least approximately total movement of the level. Preferably the movement of the level in the glass article is also effected at a regulated speed and, ideally, the shaping stage is completed by a pressure-regulated forward movement of the level.

Abstract: A method to fabricate nonlinear optical frequency doubler devices comprised of a process to form periodic tantalum masks on a LiNb.sub.x Ta.sub.1-x O.sub.3 (wherein 0.ltoreq.x.ltoreq.1) crystal substrate, a process to form periodic proton exchanged regions by applying a phosphoric acid treatment, and a process to form an optical waveguide on the surface of said crystal.According to this fabrication method of the present invention, deeper domain-inverted regions can be formed on said crystal surface, and by this, a fundamental wave can be transformed into a harmonic wave at a high efficiency.

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 includes forming on a substrate a waveguide layer of silica doped with an index of refraction raising dopant whose concentration profile in a first dimension includes a higher concentration region and an adjacent lower concentration region; and heating the waveguide layer along two spaced areas defined in the second and third dimension which define a path between them for diffusing the dopant along the first dimension from the higher concentration region to the lower concentration region to reduce the index of refraction of the higher concentration region in portions of the higher concentration region proximate the spaced areas and create a waveguide along the path.

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 relates to a method of producing waveguides by an ion exchange technique on a glass substrate. In order to be able to alleviate the tolerances allowed for the ion exchange technique, the waveguides are formed in the invention by diffusing ions which increase the refractive index away from a waveguide formed previously on the glass substrate and being wider than the optical waveguides to be produced, by using the ion exchange technique and a positive-type ion exchange mask.

Abstract: A method for producing a glass preform for use in the fabrication of an optical fiber, which includes the steps of forming a glass soot preform from a glass-forming raw material and heating the soot preform in an atmosphere containing SiF.sub.4 under a pressure higher than 2 atm. for a period of time sufficient to add fluorine during the time between the formation of the soot preform and the vitrification of it, fluorine is added at a high rate and in a larger amount.

Abstract: A buried wave guide device is produced by immersing a phosphate glass containing exchangeable ions in a molten salt. Ions are exchanged from the phosphate glass to give a wave guide whose refractive index increases sharply from a first surface to a maximum at a depth below the first surface then decreases gradually in the direction of the opposite surface.

Abstract: A method of production of mono- or multimodal lightwave guides from special substrate glasses of the glass system SiO.sub.2 -B.sub.2 O.sub.3 -Al.sub.2 O.sub.3 - K.sub.2 O-F.sup.-, with partial exchange of the Li.sup.+, Na.sup.+, and/or K.sup.+ ions present in the glass against Cs.sup.+ ions, the substrate glasses having the following compositions (in mol.-%): SiO.sub.2 45-72, B.sub.2 O.sub.3 8-25, Al.sub.2 O.sub.3 1-25, Li.sub.2 O 0-1, Na.sub.2 O 0-2, K.sub.2 O 6-18, MO 0-1 (MO= MgO, CaO, SrO, BaO, ZnO, PbO), in which a portion of the O.sup.- ions present in the glass are replaced by 1-15 mol % F.sup.- ions.

Abstract: In a plate microlens of the invention, wherein gradient index lenses each having an optical axis along a normal to a surface of a transparent base and a refractive index profile gradually changing along a direction of the optical axis and a direction perpendicular thereto are formed integrally in the transparent base; a ratio d/a (where d is a thickness of the gradient index lens on the optical axis and 2a is a diameter of the gradient index lens on a surface of the transparent base) falls within a range of 0.46 to 0.78.

Abstract: In a method of manufacturing an optical waveguide by the use of a substrate which has a first ion of a first refractive index and primary and secondary surfaces, an optical passage is formed in the substrate by diffusing through the primary surface a second ionizable species of a second refractive index greater than the first refractive index. A diffusion-accelerator layer is deposited on the secondary surface to accelerate diffusion of secondary ions resulting from the second ionizable species. To this end, the diffusion-accelerator layer is composed of an additional ionizable species which is formed into additional ions able to react with the first ions. Such reaction of the additional ions with the first ions lends itself to reduce the amount of the first ions in the substrate and to promote diffusion of the second ions into the substrate.

Abstract: A method for producing a glass preform for use in the fabrication of an optical fiber, including the steps of forming a glass soot preform from a glass-forming raw material and heating the soot preform to vitrify it, the soot preform being heated in an atmosphere comprising SiF.sub.4 under pressure higher than 1 atm. for a period of time sufficient to add fluorine, between the formation of the soot preform and the vitrification of it, fluorine being added at a high rate and in a large amount.

Abstract: Silica intended to form the core of an optical-fibre preform is deposited as an unvitrified soot inside a reaction tube, where a non-aqueous solution of dopant precursor(s) is then introduced without removing the tube from the lathe. The precursor(s) of the dopant(s) are dissolved in an anhydrous organic solvent. The solution containing the dopant precursor(s) is introduced into the reaction tube without removing the tube from the lathe so that the solution covers the whole surface of the deposited soot layer and impregnation of the deposited soot layer occurs.

Abstract: The invention relates to a method of producing optical waveguides by ion exchange technique in a glass substrate (1), the ion exchange between a source of ions (such as AgNO.sub.3) and the glass substrate (1) taking place within glass substrate surface areas (6) which do not comprise any ion exchange mask. In the method of the invention, the ion exchange mask is formed by depletion areas (5A, 5B) formed in the surface of the glass substrate.

Abstract: This invention relates to the production of an essentially colorless alkali meal oxide-Al.sub.2 O.sub.3 and/or B.sub.2 O.sub.3 -SiO.sub.2, wherein at least a portion thereof contains silver ions resulting from an ion exchange reaction wherein Ag.sup.+ ions from an external source are exchanged with alkali metal ions in the glass. The amount of exchange can be varied across a portion of the glass to impart a gradient in refractive index thereto. Such technology is especially suited to the optical engineering field, particularly the making of high performance fiber-optic components.

Abstract: Production of mono- or multimodal lightwave guides from special substrate glasses of the glass system SiO.sub.2 --B.sub.2 O.sub.3 --Al.sub.2 O.sub.3 -- K.sub.2 O--F.sup.-, with partial exchange of the Li.sup.+, Na.sup.+, and/or K.sup.+ ions present in the glass against Cs.sup.+ ions, the substrate glasses having the following compositions (in mol.-%): SiO.sub.2 45-72, B.sub.2 O.sub.3 8-25, Al.sub.2 O.sub.3 1-25, Li.sub.2 O 0-1, Na.sub.2 O 0-2, K.sub.2 O 6-18, MO 0-1 (MO=MgO, CaO, SrO, BaO, ZnO, PbO), in which a portion of the O.sup.- ions present in the glass are replaced by 1-15 mol % F.sup.- ions.

Abstract: A method for producing waveguides in a glass substrate by ion exchange comprises the method steps of: (a) applying a metal mask (44) on the glass substrate (42), this metal mask (44) leaving open the areas of the waveguides (72,74) to be provided, (b) bringing the glass substrate (42) into contact with molten metallic salt which comprises the ions to be exchanged for the ions of the glass substrate (42), (c) interconnecting by means of electrical conductors surface areas (90,92,94,96) of the metal mask (44) that are separated from each other. The surface areas (90,92,94,96) of the metal mask (44) are electrically conductively interconnected through bond wires (98). Furthermore, the surface areas (90,92,94,96) are electrically conductively connected to a metallic vessel (12) which contains the molten metal.

Abstract: An integrated optical component with ion diffused optical circuit paths in glass connected to optical fibers, comprising a transverse exit groove machined adjacent the paths, a plateau for supporting an uncoated portion of the optical fibers for connection to the paths, and a shoulder adjacent the plateau for supporting a coated portion of the fiber, the fiber endfaces being secured to the terminations of the paths by means of an adhesive; and, a method for manufacturing such a component comprising machining, approximate alignment, precise alignment, and gluing steps.

Abstract: The present disclosure makes a grating assisted optical waveguide device.

Abstract: A proton-exchange method of forming optical waveguides within a lithium-based optical substrate is disclosed which utilizes sulfuric acid as the proton source. The substrate is masked to expose the areas desired to be transformed into waveguiding regions and immersed in a heated sulfuric acid bath for a period of time sufficient to provide the exchange between the protons in the acid and the lithium in the substrate. The presence of the protons in the substrate results in increasing the extraordinary refractive index .DELTA.n.sub.e in the unmasked area so that optical guiding may be accomplished. Upon removal of the substrate from the sulfuric acid bath, the substrate must be annealed so as to drive the protons to a depth sufficient to provide effective guiding.

Abstract: A method of producing a gradient-index lens includes a first step in which a glass body is immersed into a molten salt containing ions which are able to provide a refractive index higher than that of ions constituting the glass body, in order to perform ion diffusion into the glass body. Thereafter, in a second step the glass body obtained from the first step is immersed into a molten salt containing ions which provide a refractive index lower than that of the ions of the molten salt used in the first step. In this way there is formed a predetermined refractive index distribution in the glass body.

Abstract: A novel solution of H.sub.3 BO.sub.3 dissolved in strong hydrochloric or nitric acid is used to etch fluoride glass preforms used to manufacture fluoride glass fibers. Because of the excellent cleaning ability of the present solution, as well as the absence of sub-micron deposits, the resulting fibers have excellent bending strength.

Abstract: An individual section of a glass forming machine has a cylinder for controlling the displacement of the plunger. The piston is tandem in nature so that pressure can be selectively reduced for the final portion of plunger advance and the inner diameter of the cylinder guides plunger advancement at all pressures.

Abstract: A method is described of producing an elongated glass body, particularly a preform for SiO.sub.2 -base optical waveguides, in which starting glass powder material is shaped to a porous body and the latter is sintered to form a glass body. In order to obtain uniform density throughout the porous body, the starting glass powder material is filled into and simultaneously compacted in a mold. Subsequently, the powder material compacted during the filling is consolidated by a heat treatment to result in the porous body. Molds of different design for the production of tubular or rod-shaped porous bodies are described.

Abstract: A uniform refractive index-type glass is prepared by ion exchange in which a glass containing ions of a first type is immersed in a molten salt containing ions of a second type, the ions in the molten salt having a higher refractive index than the ions in the glass. The glass is removed from the molten salt at a predetermined point and before the saturation point or equilibrium and the ion distribution becomes uniform throughout the glass. The concentration of first and second ions is not uniform from the center of the glass to its outer surface. The glass is next heated to make the concentrations of the first and second ions substantially uniform throughout the glass from the center to the outer surface. Optionally, this glass is then immersed in a molten salt containing a third type of ion having a lower refractive index than the second ion for exchange with part of the ions in the second type.

Abstract: Aluminosilicate optical glass without boron oxide, comprising 60-95 mols % silica and at least 2 mols alumina, the remainder being made up of at least one oxide of a metal selected from silver and thallium. The glass may also contain caesium. Optical waveguide preforms and methods of making the same are also disclosed.

Abstract: Ion exchangeable glass compositions containing from 50 to 90 mole percent GeO.sub.2, from 5 to 30 mole percent Al.sub.2 O.sub.3, from 3 to 30 mole percent Li.sub.2 O, up to 30 mole percent Na.sub.2 O and up to 30 mole percent K.sub.2 O are provided. In another aspect, minor amounts of anhydrous fluorides and chlorides corresponding to these oxides are added to the glass compositions to aid in water removal. Glass articles formed of the germanate glass compositions of the present invention are readily ion exchangeable when contacted with certain salts. Strengthened germanate glass articles are also provided having an inner tension region and an outer compressive surface layer which provide good mechanical strength for the formed glass article. The strengthened germanate glass articles are made using the ion exchangeable germanate glass compositions of the present invention.

Abstract: An apparatus for ensuring alignment during opening and closing of mold halves in an individual section (I.S.) glassware forming machine has a cylinder containing a pair of mutually reciprocating pistons linked to a pair of mold half actuating shafts. A pair of gear racks, each linked to one of the pistons, mesh with a common idler gear. A plug and cushion combination cushion the opening stroke of the mechanism.

Abstract: A glassware forming machine of the individual section type comprising a parison-forming station (10), an article-forming station (14), parison transferring means operable to transfer parisons to the article-forming station, and article removing means operable to remove articles from the article-forming station. The parison transferring means comprises a carriage (100), parison gripping means (114) mounted on the carriage, and servo-controlled drive means (136) operable to move the carriage (100) to and from the article-forming station (14). The article removing means comprises a further carriage (210), article gripping means (226) mounted on the carriage (210), and drive means (218, 220) operable to return the carriage (210) to the article-forming station (14). The carriages (100 and 210) are so aligned that, as the carriage (100) moves to the article-forming station (14), it pushes the further carriage (210) away therefrom.

Abstract: Disclosed is an ion exchange process and composition useful therein for creating a gradient-index profile in a glass structure which uses a monovalent metal salt bath modified by the addition of a non-monovalent metal salt which provides for complexing of the outdiffusing cation (of the ion exchange process) to prevent poisoning via that cation.

Abstract: A method of consolidating fine pores of a porous glass by impregnating the fine pores with an energy decomposable compound exemplified by SiH.sub.4. Energy is applied to the decomposable compound thereby forming active species which bond with each other and the functional groups on the surface of the fine pores three-dimensionally to thus form a glass network structure in the pores.

Abstract: An evanescent-field coupler for an optical fiber having a core and a cladding forming a guiding region located sufficiently close to the surface of the fiber along a selected length thereof to allow evanescent-field coupling of an optical signal from the guiding region to an optical fiber or other device outside the guiding region, the cladding consisting essentially of silica, the coupler comprising a vitreous layer of amorphous boron oxide or a boron oxide compound fused to the cladding and having an index of refraction substantially matching the index of refraction of the cladding.

Abstract: A process for producing an optical glass product having a predetermined distribution of refractive index in the interior of the product is disclosed. The process comprises the steps of:(a) preparing an aqueous silicate solution containing from about 0.1 to about 0.6 mol/liter of Si (as SiO.sub.2) comprising silicic acid and at least one element selected from the group consisting of rubidium, thallium and cesium;(b) mixing the silicate solution with an acidic aqueous solution, and letting the two solutions react with each other for a period of time sufficient for polymerization to produce a porous gelled product wherein the silica particles are agglomerated;(c) leaching the gelled product with a liquid selected from the group consisting of water, a weakly acidic aqueous solution, an aqueous solution having an alkali metal salt dissolved therein and an aqueous solution of organic matter capable of dissolving Rb.sub.2 O, Cs.sub.2 O, or Tl.sub.

Abstract: A cesium-containing optical glass comprising, by weight, 32-56% of SiO.sub.2, 6-25% of K.sub.2 O, 6-32% of Cs.sub.2 O, 0-30% of BaO, 0-2.5% of MgO, 5-34% of ZnO, 0-3% of ZrO.sub.2 and 0-5% of SnO.sub.2, provided that the total proportion of BaO, MgO and ZnO is 8-40% and the total proportion of ZrO.sub.2 and SnO.sub.2 is 0.2-6%. When this cesium-containing optical glass is treated in a molten bath containing potassium nitrate, the cesium ion in the glass is easily exchanged with a potassium ion and therefore, the cesium ion concentration gradually decreases radially outwardly from the central axis and the potassium ion concentration gradually increases in that direction. Thus, there is obtained a light converge-type lens in which the refractive index gradually decreases in the same direction.

Abstract: A method of fabricating an optical fiber by means of the double crucible method. A double crucible is used of which at least the inner crucible has a double-walled construction. The double wall accommodates a metal wire coil. During the fabrication of the optical fiber the core glass is heated by means of a high-frequency electric field and the crucible wall is cooled with a cooling liquid.BACKGROUND OF THE INVENTIONThe invention relates to a method of continuously fabricating optical fibers from a core glass and at least one cladding glass. The method uses an apparatus comprising two or more concentric crucibles (the "double crucible" method). The invention further relates to stepped index and graded index fibers obtained by this method and to an apparatus comprising at least two crucibles for use in this method.The "double crucible" method is a known technique for the continuous production of optical fibers of the graded index type as well as of the stepped index (monomode and multimode) type.

Abstract: A method of fabrication and the resulting structure for a birefringent transmission line having particular application as an optical waveguide. The instant transmission line is fabricated so as to be adapted to maintain the state (e.g. the polarization vector) of polarized electromagnetic radiation propagating therethrough. Birefringence in the instant transmission line is geometrically generated by producing oblong regions having different indices of refraction through a cross-section of the transmission line. A preferred technique by which to generate birefringence includes the method step of bombarding the transmission line with a supply of atomic particules, such as energetic hydrogen ions, whereby to implant a damaged region of oblong cross-section and thereby cause an internal swelling therein. By way of a preferred example, the transmission line herein described may be a single-mode optical fiber.

Abstract: The specification discloses a process for forming a graded index waveguide structure by first providing a substrate of a first selected optical material having a chosen index of refraction. Next, a patterned layer of a second optical material is formed on one surface of the substrate or, optionally, within selected cavities formed in the substrate. This second optical material has a refractive index which is larger than the refractive index of the substrate. The patterned layer of the second optical material is formed in a predetermined geometry and to a predetermined thickness. Then, a layer of a third selected optical material is formed on the patterned layer of the second optical material and on the substrate surface to a predetermined thickness. This third optical material has a refractive index which is substantially the same as the refractive index of the substrate.

Abstract: A process for making an optical fiber includes the steps of inserting a rod of the core glass composition into a closed tube made of the cladding glass. The diameter of the rod is substantially less than the inner diameter of the tube. The glass transition temperature of the core glass must be substantially lower than the glass transition temperature of the cladding and the rod is placed in contact with the tube along its entire length. When heat is applied to the lower portion of the rod and tube, the rod melts and forms a thin film on the inner surface of the tube which can rapidly be fined to a relatively pure glass. This melted glass forms a melt pool in the bottom of the tube, and the tube and pool can then be drawn into a fiber with the desired characteristics. A process for making a graded optical fiber utilizing a modified chemical vapor deposition process is also disclosed wherein a cladding glass is entrained on the inner surface of a tube substrate.