Abstract: A process for the production of homogeneous ream-free bodies made of quartz glass or made of a glass having a high content of silicic acid, in which an essentially bar-shaped initial body is twisted about its longitudinal axis in a shaping step to form a twisted body radially homogenized in layers having axial layering. To make it possible to produce homogeneous large-volume bodies, in at least one further shaping step the twisted body is then softened in a heatable mold under a force acting in the axial direction to deform it in a direction transverse to its axial direction into the mold and form a glass bar, the longitudinal axis of which extends essentially perpendicular to the layering. The glass bar is then twisted about its longitudinal axis.

Abstract: Granular silicon dioxide is placed in a treatment chamber which is heated to a temperature ranging from 700.degree. to 1300.degree. C. The chamber is then rotated for a prescribed period of time to mix the grains while a gaseous atmosphere of chlorine and/or hydrogen chloride is passed through the treatment chamber. The mixing period is followed by a resting period which is at least ten times longer than the mixing time. During the resting period the grains are exposed to a constant electric field having a strength of 600 to 1350 V/cm applied across the chamber. The foregoing cycle is repeated several times. For working the process a device is used which includes a quartz glass rotary tube into which hollow silicon carbide electrodes extend.

Abstract: A method of vitrifying a porous cylindrical article made out of glass soot, especially for manufacturing a preliminary blank for optical fibers. The article is heat-treated in a furnace in a vacuum or in an atmosphere that contains helium. The porous article is placed in a horizontal graphite tube in the furnace, is sintered therein for 20 to 40 minutes in a vacuum or in a helium atmosphere with reduced pressure at 1250.degree. to 1400.degree. C., and is subsequently vitrified by heat-treating the sintered article at first in the sintering atmosphere, while slowly rotating it in the hot graphite tube for 20 to 40 minutes at approximately 1450.degree. to 1600.degree. C. and then while rotating it in the graphite tube more rapidly than in the first stage for 10 to 30 minutes at approximately 1650.degree. to 1750.degree. C.

Abstract: Disclosed is a method for the axial building up, in a vertical arrangement, of a hollow cylindrical soot body having no internal support and consisting substantially of silicon dioxide by means of at least one flame hydrolysis build-up burner serving for the soot production. In this method the soot is deposited at the beginning of the build-up onto an auxiliary body, and during the build-up the build-up burner and the growing soot body are rotated relative to one another, and the burner is at the same time held at an unvarying distance from the growing end of the hollow cylinder and centrally above the predetermined cross section of the upwardly growing end of the cylinder wall. The penetration of soot into the interior of the cylinder is prevented by means of a directed gas stream.

Abstract: A method of manufacturing practically stria-free, bubble-free, and homogeneous quartz-glass plates of any desired configuration and with a surface area that exceeds the cross-section of the full circular quartz-glass cylinder that is employed as a starting material. The cylinder is continuously lowered into a furnace shell flooded with an inert gas, in which it is heated to a flowing temperature in the range of 1700.degree. to 1900.degree. C. until some of the quartz-glass flows off into a graphite crucible. The crucible is preferably clad with zirconium-oxide.

Abstract: A method of manufacturing practically stria-free, bubble-free, and homogeneous quartz-glass plates of any desired configuration and with a surface area that exceeds the cross-section of the full circular quartz-glass cylinder that is employed as a starting material. The cylinder is continuously lowered into a furnace shell flooded with an inert gas, in which it is heated to a flowing temperature in the range of 1700.degree. to 1900.degree. C. until some of the quartz-glass flows off into a graphite crucible. The crucible is preferably clad with zirconium-oxide.

Abstract: Flat, transparent slabs of vitreous silica of optical quality are produced by melting granular starting material in a vacuum by means of an electrical heating system. The starting material is melted while sustaining a heat flow from the top to the bottom of the crucible. The bottom of the crucible is made permeable to gases. The heat isolation power of the crucible wall increases from the bottom to the top of the crucible.

Abstract: The lightweight mirror has a special core construction. The core consists of flat and/or tubular pieces which are joined together by means of a sintering composition. The sintering composition has open pores. In the production of the core, the sintering composition is poured into interstices between pairs of adjacent flat and/or tubular pieces and heated to the sintering temperature in a nonoxidizing atmosphere together with the flat and/or tubular pieces. A layer of sintering composition can be provided on the faces of the front and/or back plate of the lightweight mirror which confront the core. Stiffening rods can be embedded in the sintering composition.

Abstract: Flat, transparent slabs of vitreous silica of optical quality are produced by melting granular starting material in a vacuum by means of an electrical heating system. The starting material is melted while sustaining a heat flow from the top to the bottom of the crucible. The bottom of the crucible is made permeable to gases. The heat isolation power of the crucible wall increases from the bottom to the top of the crucible.

Abstract: A semiproduct for use in the manufacture of light conducting fibers comprising a core of synthetic quartz glass having a thickness of 6 to 400 mm, the quartz glass containing less than 10 ppm hydroxyl ions and having, in the near infrared spectral range, an optical loss totaling less than 4 dB/km, measured in the mass, the core being fused with a jacket having a wall thickness of 2 to 20 mm and consisting essentially of synthetic quartz glass containing more than 4,000 ppm of fluorine, the jacket having a length of at least 200 mm; a method of producing the same and light conducting fibers derived therefrom.

Abstract: A semiproduct for use in the manufacture of light conducting fibers comprising a core of synthetic quartz glass having a thickness of 6 to 400 mm, the quartz glass containing less than 10 ppm hydroxyl ions and having, in the near infrared spectral range, an optical loss totaling less than 4 dB/km, measured in the mass, the core being fused with a jacket having a wall thickness of 2 to 20 mm and consisting essentially of synthetic quartz glass containing more than 4,000 ppm of fluorine, the jacket having a length of at least 200 mm; a method of producing the same and light conducting fibers derived therefrom.

Abstract: An improvement in a method for producing a synthetic hydroxyl ion-free quartz glass wherein a hydrogen free silicon compound is heated in a hydrogen-free gas stream while the gas stream is passed through an induction coupled plasma burner, the gas stream containing elemental and/or bound oxygen and the oxidation product is deposited on a refractory support as a vitreous mass, the improvement lying in including in the gas stream a gaseous hydrogen-free, thermally decomposable compound which yields fluorine in an amount of at least 500 gms. per kilogram of silica to be produced; an apparatus for producing a synthetic OH ion-free quartz glass comprising an induction coupled plasma burner which burner has disposed thereabout 3 concentric quartz glass tubes disposed in stepped configuration of which the outermost tube is the longest and the innermost tube is the shortest.

Abstract: Quartz glass element, such as a diffusion tube useful in the production of semiconductor elements, capable of forming an outer layer of uniformly fine crystalline silica such as cristobalite or tridymite when heated to a temperature at which such crystalline silica forms containing crystallization promoting nuclei having a rate of diffusion in quartz glass less than that of sodium at elevated temperatures. Such nuclei are preferably present in the outer half of the element wall. When the quartz glass element is exposed to elevated temperatures, the nuclei promotes the formation of the outer layer of uniformly fine crystalline silica which imparts thermal dimensional stability for extended periods of use at elevated temperatures.

Abstract: There is disclosed a process for preparing a foreproduct useful in the production of an optical self-focusing lightconductor in which the index of refraction of the lightconductor diminishes with increasing distance from the conductor axis such that, when plotted against the conductor diameter, the refractive index curve is parabolic and the apex of the parabola lies over the center of the conductor diameter wherein a plurality of layers of doped silica are deposited on a cylindrical support, the layers being formed of a mixture of a vaporous silicon compound and a vaporous doping agent at elevated temperature. The invention involves depositing at least one layer of undoped silica between layers of doped silica and following each deposition of each doped or undoped silica layer by heating step in which the material is heated to a temperature of at least 900.degree. C to vitrify the same. Each layer is deposited in a thickness ranging from 0.1 to 20 .mu.m.

Abstract: An improvement in a method for producing a synthetic hydroxyl ion-free quartz glass wherein a hydrogen free silicon compound is heated in a hydrogen-free gas stream while the gas stream is passed through an induction coupled plasma burner, the gas stream containing elemental and/or bound oxygen and the oxidation product is deposited on a refractory support as a vitreous mass, the improvement lying in including in the gas stream a gaseous hydrogen-free, thermally decomposable compound which yields fluorine in an amount of at least 500 gms. per kilogram of silica to be produced; an apparatus for producing a synthetic OH ion-free quartz glass comprising an induction coupled plasma burner which burner has disposed thereabout 3 concentric quartz glass tubes disposed in stepped configuration of which the outermost tube is the longest and the innermost tube is the shortest.