Abstract: Solid glass articles are made by the flame hydrolysis technique. A thin stratum of low viscosity glass soot is applied to the surface of a mandrel. First and second coatings of glass soot are deposited on the surface of the thin stratum to form a porous preform. The refractive index of the soot particles of the first coating is greater than that of the soot of the second coating, and the soot of the first coating has a viscosity lower than that of the second coating. The mandrel is removed, and the soot preform is subjected to a high temperature whereby it is consolidated to form a dense glass blank. The glass surface tension and the relative viscosities of the inner and outer portions of the preform cause the aperture to close during the consolidation process. The thin stratum, which preferably includes P.sub.2 O.sub.5, smoothes over the damage caused by removing the mandrel and reduces or even eliminates seed formation at the axis of the resultant glass blank.

Abstract: Disclosed are a method and apparatus for improving the fatigue characteristics of a glass optical waveguide fiber. After the fiber is drawn and before it is provided with a protective coating it is heated to a temperature within the annealing temperature range. A filtered gas may be flowed over the fiber during the step of heating.

Abstract: An article suitable as an integral handle for an optical waveguide preform is disclosed. The article comprises a hollow tubular member defining a substantially longitudinal aperture and having one end thereof tapered and of diminishing wall thickness for the length of said taper. Adjacent the tapered end is disposed an outwardly extending protrusion which is embedded in one end of an optical waveguide preform forming an integral unit therewith. Means are provided for a substantially gas-tight connection to the handle so that a gaseous medium may be flowed through the handle and the optical waveguide preform in its porous soot form. Means are also provided for attaching and securing the composite structure to a source of gaseous medium. Also disclosed is the combination of an optical waveguide preform rigidly affixed to a handle.

Abstract: A method of making solid glass articles by the flame hydrolysis technique. A thin stratum of low viscosity glass soot is applied to the surface of a mandrel. First and second coatings of glass soot are deposited on the surface of the thin stratum to form a porous preform. The refractive index of the soot particles of the first coating is greater than that of the soot of the second coating, and the soot of the first coating has a viscosity lower than that of the second coating. The mandrel is removed, and the soot preform is subjected to a high temperature whereby it is consolidated to form a dense glass blank. The glass surface tension and the relative viscosities of the inner and outer portions of the preform cause the aperture to close during the consolidation process. The thin stratum, which preferably includes P.sub.2 O.sub.5, smoothes over the damage caused by removing the mandrel and reduces or even eliminates seed formation at the axis of the resultant glass blank.

Abstract: An article suitable as an integral handle for an optical waveguide preform is disclosed. The article comprises a hollow tubular member defining a substantially longitudinal aperture and having one end thereof tapered and of diminishing wall thickness for the length of said taper. Adjacent the tapered end is disposed an outwardly extending protrusion which is embedded in one end of an optical waveguide preform forming an integral unit therewith. Means are provided for a substantially gas-tight connection to the handle so that a gaseous medium may be flowed through the handle and the optical waveguide preform in its porous soot form. Means are also provided for attaching and securing the composite structure to a source of gaseous medium. Also disclosed is the combination of an optical waveguide preform rigidly affixed to a handle.

Abstract: A method of forming a preform suitable for optical waveguides is disclosed. The method comprises providing a hollow tubular member defining a substantially longitudinal aperture and having one end thereof tapered and of diminishing wall thickness for the length of said taper. Adjacent the tapered end is formed an outwardly extending protrusion. A starting mandrel is inserted into the aperture so as to extend therebeyond. Particulate material is deposited over at least a portion of each of the extending part of the hollow tubular member and the starting mandrel whereby the extending protrusion is embedded in one end of the resulting optical waveguide preform. An integral unit including the tubular member and the preform is thus formed. Means are provided for a substantially gas-tight connection to the handle so that a gaseous medium may be flowed through the handle and the optical waveguide preform in its porous soot form.

Abstract: A substantially continuous method for drying, consolidating and drawing an optical waveguide preform is disclosed. A porous soot preform suspended from a substantially hollow longitudinal preform handle having a longitudinal aperture therein is provided. The end of the hollow preform handle is connected to a source of gaseous drying medium, and a quantity of the gaseous drying medium is flowed through the aperture in the porous soot preform and through the porous walls of the preform thereby drying the preform structure. The extending end of the porous soot preform is heated to the consolidation temperature of the materials thereof to progressively consolidate the preform from the extending end thereof. The consolidated end of the preform is further heated to the drawing temperature of the materials thereof and a filament is drawn from the extending end of the consolidated preform.

Abstract: A method of making glass optical waveguides by the flame hydrolysis technique. Particles of glass soot produced by flame hydrolysis are deposited on the outside surface of a mandrel to form a porous preform. The soot particles closer to the mandrel have a refractive index greater than that of the soot disposed toward the outer surface of the preform. The mandrel is removed and the resultant hollow soot preform is supported in a draw furnace through which a helium-rich gas flows. The preform is heated to a temperature sufficient to cause said soot to consolidate and simultaneously permit an optical waveguide filament to be drawn therefrom.

Abstract: A method of forming an article such as an optical waveguide filament by disposing a draw blank in a cylindrical muffle. The muffle is heated to a temperature sufficient to cause a first end of the blank to reach the drawing temperature of the material thereof. A filament is drawn from the first end of the blank while a helium-containing gas flows through the muffle in such a direction that it is exhausted from that end of the muffle from which the filament is being drawn.

Abstract: An apparatus is disclosed for drawing glass optical waveguide filaments having minimal diameter variation. A draw blank is supported within an elongated, heated, tubular muffle which heats the blank to its draw temperature. Gas is supplied to that end of the muffle opposite that from which the filament is drawn. A cylindrically shaped member at least 10 cm long is disposed adjacent to the end of the blank opposite the filament to form with the inner wall of the muffle a thin, cylindrically-shaped channel through which the gas must flow. The gas stream is thus uniformly heated at the time that it reaches the root of the filament so that diameter variations due to gas turbulence are minimized.